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HP 5890 Series II and
HP 5890 Series II Plus
Operating Manual
HEWLETT
PACKARD
Manual Part No.
05890-90260
Edition 8, November 1993
Printed in U.S.A.
Printing History
The information contained in this document may be revised without notice.
Hewlett-Packard makes no warranty of any kind with regard to this material,
including, but not limited to, the implied warranties of merchantability and fitness
for a particular purpose. Hewlett-Packard shall not be liable for errors
contained herein or for incidental, or consequential damages in connection
with the furnishing, performance, or use of this material.
No part of this document may be photocopied or reproduced, or translated to
another program language without the prior written consent of
Hewlett-Packard Company.
First edition—June 1989
Second edition—October 1989
Third edition—January 1990
Fourth edition—October 1990
Fifth edition—October 1991
Sixth edition—September 1992
Seventh edition—June 1993
Eighth edition—November 1993
Printed in U.S.A.
® Copyright 1993 by Hewlett-Packard Company
All Rights Reserved. Reproduction, adaptation, or translation without prior written
permission is prohibited, except as allowed under the copyright laws.
Safety Information
The HP 5890 Series II and HP 5890 Series II Plus are IEC (International
Electrotechnical Commission) Safety Class 1 instruments. This unit has been
designed and tested in accordance with recognized safety standards.
Whenever the safety protection of the HP 5890 Series II and HP 5890
Series II Plus have been compromised, disconnect the unit from all power
sources and secure the unit against unintended operation.
Safety Symbols
This manual contains safety information that should be followed by the user to
insure safe operation.
WARNING
A WARNING CALLS ATTENTION TO A CONDITION OR POSSIBLE SITUATION THAT COULD CAUSE INJURY TO THE USER.
A Caution calls attention to a condition or possible situation
that could damage or destroy the product or the user's work.
DECLARATION OF CONFORMITY
according to ISO/IEC Guide 22 and EN 45014
Manufacturer's Name:
Manufacturer's Address:
Hewlett-Packard Co.
Little Falls Site 4300
2850 Centerville Rd.
Wilmington, DE 19808
declares that the product
Gas Chromatograph
5890 Series II
002,211,221,552, 110
Product Name:
Model Number:
Product Option:
conforms to the following Product Specifications:
EMC:
Vfg 523/1969
VDE 0871 Class A
Safety:
IEC 348:1978 (Second Edition) / HD 401:1980
CSA C22.2 No. 151-M1986
UL 1262 (Third Edition)
Supplementary information:
1 The product was tested in a typical configuration, including 7673B and
bar code reader.
2 CSA Certified
3 ETL (NRTL) Listed
Wilmington, DE, USA, Feb 26, 1993
Liza Baffle, Quality Manager
Contents
( ,
Chapter 1: Getting Started
Installation Checklist
Daily Startup
Daily Shutdown
Chapter 2:
\m^/'
1-1
1-2
1-2
Installing Columns
Preparing Fused Silica Capillary Columns
2-2
Installing Split/Splitless Capillary Inserts
2-4
Preparing Packed Metal Columns
2-6
Installing 1/4- and 1/8-inch Metal Columns in Packed Inlets
2-8
Installing 1/4-in Glass Columns in Packed Inlets
2-10
Installing Capillary Columns in Packed Inlets
2-12
Installing Capillary Columns in Split/Splitless Capillary Inlets
2-14
Installing 1/4-in Metal Columns in Flame Ionization and Nitrogen-Phosphorus Detectors . 2-16
Installing 1/8-in Metal Columns in Flame Ionization and Nitrogen-Phosphorus Detectors . 2-18
Installing Capillary Columns in Flame Ionization and
Nitrogen-Phosphorus Detectors
2-20
Installing an 1/8-inch Metal Column in a Thermal Conductivity Detector
2-22
Installing a Capillary Column in a Thermal Conductivity Detector
2-24
Installing a 1/4-inch Glass Column in an Electron Capture Detector
2-26
Installing a Capillary Column in an Electron Capture Detector
2-28
Installing an 1/8-inch Metal Column in a Flame Photometric Detector
2-30
Installing a Capillary Column in a Flame Photometric Detector
2-32
Chapter 3: Setting Heated Zone Temperatures
t ^
Operating Limits for Heated Zones
Setting Oven Temperatures
Displaying Oven Temperature
Examples
Setting Oven Temperature to 200°C
Setting Oven Equilibration Time to 1 Minute
Setting the Oven Maximum to 350°C
Using Cryogenic Oven Cooling
Programming Oven Temperatures
Examples
3-3
3-4
3-4
3-5
3-5
3-5
3-5
3-6
3-8
3-9
Setting Inlet and Detector Temperatures
Displaying Inlet and Detector Temperature
Example
Setting Inlet Temperature to 200°C
Setting Detector Temperature to 200°C
Setting Auxiliary Temperatures
3-13
3-13
3-14
3-14
3-14
3-15
Chapter 4: Setting Inlet System Flow Rates
Measuring Flow Rates
Using a Bubble Flow Meter
Required Adapters for Measuring Flow Rates
Changing the Packed Inlet Flow Ranges
Changing the Source Pressure
Setting the Packed Inlet Flow with Septum Purge
Manual Flow Control:
Electronic Pressure Control:
Setting the Split/Splitless Capillary Inlet Flow
Setting the Split Mode Flow
Manual Flow Control:
Electronic Pressure Control:
Setting the Splitless Mode Flow
Manual Flow Control:
Electronic Pressure Control:
Manual Purge Switching:
Automatic Purge Switching:
Displaying the Gas Flow Rate
Designating Gas Type
Using the Internal Stopwatch
Chapter 5:
4-1
4-2
4-4
4-5
4-5
4-6
4-6
4-7
4-9
4-11
4-11
4-12
4-18
4-18
4-19
4-21
4-21
4-25
4-25
4-27
Operating Detector Systems
Displaying Detector Status
Turning a Detector On or Off
Monitoring Detector Output
Operating Detectors Using Electronic Pressure Control
Accessing Auxiliary Channels C through F
Zeroing the Pressure Channel
Setting Constant Pressure
Setting Pressure Ramps
Changing Pressure Ramps
Example of Setting Pressure Ramps
Verifying Pressure Ramps
5-2
5-3
5-4
5-5
5-6
5-7
5-8
5-9
5-9
5-10
5-11
Setting Capillary Makeup Gas Flow Rate
Exceptions to Makeup Gas Flow
If the Power Fails
Shutting Down Each Day
5-12
5-12
5-15
5-15
Operating the Flame Ionization Detector (FID)
Setting Up the FID for Operation
Setting the FID Flow for Packed Columns
Setting the FID Flow for Capillary Columns
Setting the Makeup Gas Flow Rate
Turning the FID On and Off
Igniting the FID Flame
5-16
5-17
5-19
5-21
5-26
5-27
5-28
Operating the Thermal Conductivity Detector (TCD)
Setting Up the TCD for Operation
Setting the TCD Flow for Packed Columns
Setting the TCD Flow for Capillary Columns
Setting the TCD Carrier Gas Type
Setting the TCD Sensitivity
Turning the TCD On and Off
Inverting the TCD Polarity
Using Single-Column Compensation (SCC)
Displaying the Column Compensation Status
Initiating a Column Compensation Run
Assigning Column Compensation Data
5-29
5-30
5-30
5-31
5-33
5-34
5-35
5-35
5-36
5-37
5-38
5-40
Operating the Nitrogen-Phosphorus Detector (NPD)
Setting Up the NPD for Operation
Conditioning the NPD Active Element (Bead)
Setting the NPD Active Element (Bead) Power
Setting the NPD Flow for Packed Columns
Setting the NPD Flow for Capillary Columns
Turning the NPD On and Off
Optimizing the Performance of the NPD
Avoiding Contamination
Preserving the Lifetime of the Active Element
5-42
5-43
5-44
5-45
5-47
5-49
5-52
5-53
5-53
5-54
Operating the Electron Capture Detector (ECD)
Requirements for USA Owners
Introduction
General Considerations
Temperature Effects
Gases
Columns and Flow Rates
Background
Setting Up the ECD for Operation
Setting the Carrier/Makeup Gas Selection Switch
Setting the ECD Flow for Packed Columns
Setting the ECD Flow for Capillary Columns
Testing for Contamination
Testing for Leaks
Testing for Radioactive Leaks (the Wipe Test)
5-56
5-57
5-58
5-59
5-59
5-59
5-60
5-60
5-60
5-61
5-62
5-63
5-66
5-67
5-67
Operating the Flame Photometric Detector (FPD)
Setting Up the FPD for Operation
Setting the FPD Flow for Packed Columns
Setting the FPD Flow for Capillary Columns
Turning the FPD On and Off
Igniting the FPD Flame
5-68
5-68
5-69
5-71
5-74
5-74
Chapter 6: Controlling Signal Output
Assigning a Signal
Displaying or Monitoring a Signal
Zeroing Signal Output
Turning Zero Off/On
Setting Signal Attenuation
Turning Attenuation Off/On
Inverting TCD Signal Polarity
Using Instrument Network (INET)
6-2
6-5
6-7
6-8
6-9
6-12
6-12
6-14
Chapter 7:
^1|^_/'
Making a Run
Starting/Stopping a Run
INET Start/Stop Operation
Status LEDs
Using the Time Key
Using Single-Column Compensation
Displaying Column Compensation Status
Initiating a Column Compensation Run
Assigning Column Compensation Data
Using Instrument Network (INET)
Using Timetable Events
Turning Valves On/Off During a Run
Switching Signals During a Run
Changing TCD Sensitivity During a Run
Modifying Timetable Events
7-1
7-1
7-2
7-6
7-8
7-9
7-10
7-12
7-14
7-15
7-18
7-20
7-22
7-23
Chapter 8: Storing and Loading HP 5890 Series II Setpoints
Storing GC Setpoints
Loading GC Setpoints
^-^
8-1
8-2
Chapter 9: Controlling Valves
Turning Valves On/Off Manually
9-2
Chapter 10: Using Electronic Pressure Control
v .
What Is Electronic Pressure Control?
Using Electronic Pressure Control with Inlets (EPC)
Using Electronic Pressure Control with Detectors (Auxiliary EPC)
Safety Shutdown for Electronic Pressure Control
What Happens During Electronic Pressure Control Safety Shutdown?
Summary Table of Safety Shutdown
Setting Inlet Pressure Using Electronic Pressure Control
Zeroing the Pressure
Setting Constant Flow Mode
Setting Inlet Pressure Programs
Checking Inlet Pressure Programs
Setting Pressure Using Auxiliary Electronic Pressure Control
How Do I Access Auxiliary Electronic Pressure Control?
Setting Constant Detector Pressure
Setting Detector Pressure Programs
Checking Detector Pressure Programs
10-1
10-2
10-2
10-4
10-4
10-5
10-6
10-6
10-8
10-9
10-11
10-12
10-13
10-14
10-15
10-16
Suggested Ranges for Operating Auxiliary Electronic Pressure Control
Using Electronic Pressure Control to Control Gas Flow
Accessing the Flow Parameter Displays
Selecting the Gas Type
Setting the Column Diameter
Setting the Column Length
Using Vacuum Compensation Mode
Using Constant Flow Mode for Inlets
Setting Mass Flow Rate for Inlets
Setting Inlet Flow Programs
Setting the Average Linear Velocity
Understanding Average Linear Velocity
Calculating Outlet Flow
Setting the Average Linear Velocity
Determining the Corrected Column Length
Packed Column Considerations
Capillary Column Considerations
Optimizing Splitless Injection Using Electronic Pressure Control
Operating the Gas Saver Application for the Split/Splitless Inlet
What Is the Gas Saver Application?
What Are the Required Settings for Operation?
How Is the Gas Saver Application Configured?
How Does the Gas Saver Application Operate?
Zero the Channel
Enter the Carrier Gas Pressure
Enter the Column Parameters
Set the System to Operating Conditions
Set the System to Off-Hour Conditions
Recommended Flow Rates for Inlet Systems Using the Gas Saver Application
Additional Benefits of the Gas Saver Application
Using the External Sampler Interface
Which Configuration Should I Use?
Using the External Sampler Interface with an Inlet as a Heated Zone
Special Considerations
Using Valve Options
Which Valves Work Best with Auxiliary Electronic Pressure Control?
10-17
10-22
10-24
10-25
10-26
10-26
10-27
10-28
10-29
10-30
10-32
10-32
10-33
10-33
10-34
10-34
10-34
10-36
10-38
10-38
10-38
10-39
10-40
10-40
10-41
10-41
10-42
10-42
10-43
10-43
10-44
10-44
10-54
10-54
10-57
10-60
Appendix A
Pressure—Flow Relationships for Inlet and Auxiliary Electronic Pressure Control
Outlet Flow
Average Linear Velocity
Calculating Flow from Average Linear Velocity
Example 1—Inlet Pressure 4.6 psig
Example 2—Inlet Pressure 8.3 psig
Example 3—Inlet Pressure 14.3 psig
References
A-l
A-2
A-2
A-3
A-4
A-4
A-5
A-5
Contents
Chapter 1: Getting Started
Installation Checklist
Daily Startup
Daily Shutdown
1-1
1-2
1-2
1
Getting Started
Installation Checklist
This checklist will help you get your HP 5890 Series II into operation. All references are to the
HP 5890 Series II Manual Set.
Checklist
Location
1. Select a location for the instrument.
Site Prep and Installation, Chapter 1
2. Check the new instrument for damage
in shipment.
Site Prep and Installation, Chapter 2
3. Make sure everything is present.
Site Prep and Installation, Chapter 2
4. Place the instrument in position and
make all connections.
Site Prep and Installation, Chapter 2
5. Turn the instrument on.
Site Prep and Installation, Chapter 2
6. Install a column.
Operating, Chapter 2
7. Set the inlet system flow rate.
Operating, Chapter 4
8. Set appropriate heated zone temperatures.
Operating, Chapter 3
9. Set the detector system flow rates.
Operating, Chapter 5
10. Turn the detector on.
Operating, Chapter 5
11. The instrument is now ready to
make a run.
Operating, Chapter 7
Getting Started
1-1
Daily Startup
1. Check that the operating conditions are correct for your analysis. Make any changes that
are needed.
2. Reset the detector sensitivity if you lowered it overnight.
3. If you're using temperature programming, make a blank run (no sample) to clean out any
septum bleed or carrier gas impurities that might have accumulated in the column.
4. Start your analysis.
Daily Shutdown
1. In most cases, leave the detectors on and at operating temperature. This will avoid a long
equilibration time in the morning. You may want to reduce the sensitivity, particularly
with the TCD and NPD detectors, to prolong their lifetime.
2. Leave the carrier flow on to protect the column(s). For extended shut-down periods, cool
the oven to room temperature and then turn the carrier flow off.
3. Now is a good time to change the inlet septum if needed. Volatile material will be baked
out overnight. But keep the columns warm so that the baked-out material doesn't
accumulate on the column. You can generally expect 1- or 2-days use from a septum, but
this is reduced by high temperatures, many injections, dull or hooked needles, etc. It's
best to avoid trouble by changing them daily.
Getting Started
1-2
Contents
Chapter 2:
Installing Columns
Preparing Fused Silica Capillary Columns
Installing Split/Splitless Capillary Inserts
Preparing Packed Metal Columns
Installing 1/4- and 1/8-inch Metal Columns in Packed Inlets
Installing 1/4-inch Glass Columns in Packed Inlets
Installing Capillary Columns in Packed Inlets
Installing Capillary Columns in Split/Splitless Capillary Inlets
Installing 1/4-inch Metal Columns in Flame Ionization and
Nitrogen-Phosphorus Detectors
Installing 1/8-inch Metal Columns in Flame Ionization and
Nitrogen—Phosphorus Detectors
Installing Capillary Columns in Flame Ionization and Nitrogen-Phosphorus Detectors . . . .
Installing an 1/8-inch Metal Column in a Thermal Conductivity Detector
Installing a Capillary Column in a Thermal Conductivity Detector
Installing a 1/4-inch Glass Column in an Electron Capture Detector
Installing a Capillary Column in an Electron Capture Detector
Installing an 1/8-inch Metal Column in a Flame Photometric Detector
Installing a Capillary Column in a Flame Photometric Detector
2-2
2-4
2-6
2-8
2-10
2-12
2-14
2-16
2-18
2-20
2-22
2-24
2-26
2-28
2-30
2-32
2
Installing Columns
The HP 5890 Series II and Series II Plus (hereafter referred to as HP 5890) provide flexibility
in choices among inlets, columns, and detectors through use of liners and adapters, allowing
any standard column to be used without sacrificing performance. Additional flexibility is gained
through positions of inlets and detectors relative to each other and through the large internal
volume of the oven.
Note: The Series 530 |i columns supplied with the HP 5890 must be conditioned before use.
This is done by establishing a flow of carrier gas at 30 to 60 ml/min through the column while
the column is heated at 250° C for at least 4 hours. See Preventive Maintenance in the HP 5890
Series IIReference Manual for more information about conditioning columns.
New columns should be conditioned because they often contain volatile contaminants absorbed
from the air. It may also be necessary to condition a used column that has been stored for some
time without end caps or plugs to exclude air.
This section provides information required for proper column installation:
•
Liners and inserts
•
Preparing packed columns
•
Installing packed columns
•
Preparing capillary columns
•
Installing capillary columns
Installing Columns 2-1
Preparing Fused Silica Capillary Columns
Fused silica columns are inherently straight, so no straightening procedures are necessary. It IS
important, however, to have fresh ends of the column, free of burrs, jagged edges, and/or loose
particles of column, stationary phase, and/or material from a sealing ferrule or O-ring.
Therefore, whenever the column must be cut to provide fresh ends, use a suitable glass scribing
tool (HP ceramic column cutter, part number 5181-8836) to first score the column at the point
at which it is to be broken. This is done normally AFTER installing on the column, the column
nuts and ferrule (or O-ring) required for installation.
WARNING
WEAR SAFETY GLASSES TO PREVENT POSSIBLE EYE INJURY FROM
FLYING PARTICLES WHILE HANDLING, CUTTING, OR INSTALLING
GLASS OR FUSED SILICA CAPILLARY COLUMNS. ALSO OBSERVE
CAUTION IN HANDLING CAPILLARY COLUMNS TO PREVENT SKIN
PUNCTURE WOUNDS.
BECAUSE OF THEIR GREATER RELATIVE RIGIDITY, THESE
PRECAUTIONS ARE ESPECIALLY IMPORTANT IN HANDLING
HEWLETT-PACKARD SERIES 530 |i CAPILLARY COLUMNS.
Installing Columns 2-2
Score
Break Point
Ferrule
Column Nut
I
I
Preparing Fused Silica Capillary Columns
Installing Columns 2-3
Installing Split/Splitless Capillary Inserts
A specific inlet insert is required, depending upon the particular sampling mode. Specific
sampling modes include:
•
Split, for major-component analyses
•
Purged splitless, for trace-component analyses
WARNING
EXERCISE CARE! THE OVEN, AND/OR INLET, OR DETECTOR
FITTINGS MAY BE HOT ENOUGH TO CAUSE BURNS.
If operating in split mode, carrier gas pressure must be reduced before
opening the inlet. If not done, pressure may blow insert packing out of
the inlet, altering its characteristics. Pressure is reduced at the column
head pressure regulator for the inlet.
1. In handling the insert, avoid contaminating its surface (particularly its interior).
2. Remove the insert retainer nut. The septum retainer nut need not be removed from the
insert retainer nut assembly.
3. Using tweezers, forceps, or similar tool, remove any insert already in place.
4. Inspect the new insert to be installed: For a split mode insert, the end with the mixing
chamber and packing is inserted first into the inlet.
5. Place a graphite or silicone O-ring on the insert, about 2 to 3 mm from its top end.
6. Replace the insert retainer nut, tightening it to FIRM finger-tightness to form a leak-free
seal. Do not overtighten.
Installing Columns 2-4
Installing Split/Splitless Capillary Inserts
Installing Split/Splitless Capillary Inserts
Installing Columns 2-5
Preparing Packed Metal Columns
Packed metal columns are installed similarly at both the inlet and detector. To minimize
unswept (dead) volume column inside the inlet or detector fitting, it is recommended that
ferrule(s) be preset and locked onto the column such that the end of the column is approximately flush with the end of the front ferrule (see figure at the top of next page).
If not already installed, follow the procedure below to install NEW swage-type nut and ferrules.
For metal columns with ferrules already installed and set, proceed to instructions for installing
metal columns in this section.
To insure the correct column position, a spacer may be made from a piece of Teflon tubing:
1. According to the column to be installed (1/8 or 1/4 inch), secure an appropriate NEW
male swage-type fitting in a bench vice.
2. Slide a NEW, brass, swage-type nut, rear ferrule, and front ferrule onto a piece of Teflon
tubing (1/8 or 1/4 inch). If necessary, use a razor or sharp knife to cut the end of the
tubing to present a flat, smooth end.
3. Fully insert the Teflon tubing, ferrules, and nut into the vise-held swage-type fitting.
Tighten the nut 3/4-turn past finger-tight to set the ferrules on the tubing. Then remove
the assembly from the male fitting.
4. Using a razor knife, cut off the end of the tubing extending beyond the front-most ferrule.
Insert the piece into the vise-held swage-type fitting.
This piece of tubing is now a spacer, insuring that when new ferrules are set onto a column, the
column end will be correctly positioned with respect to the end of the front-most ferrule. The
male fitting and spacer should be kept on hand to be used whenever new ferrules are being
installed on a column.
5. Install a NEW swage-type nut and ferrule(s) onto the column.
6. Fully insert the column with its nut and ferrules into the vise-held fitting.
7. First tighten the nut finger-tight. Use a wrench to tighten the column nut an additional
1- and -1/4 turns for 1/4-inch columns, or 3/4-turn for 1/8-inch columns.
8. Unscrew the column nut from the vise-held fittings, and remove the column. Ferrules
should now be set in place on the column, with the column correctly positioned.
Installing Columns 2-6
Not Desirable
(May cause problems due
to dead volume)
Recommended
Minimum Exposed
Column
Recommended Location for Ferrules on Packed Columns
Exposed Teflon Tube
to be Cut -
Cut Spacer
Spacer Installed
in Fitting
Teflon Tubing
Making a Teflon Spacer
Preparing Packed Metal Columns
Installing Columns 2-7
Installing 1/4- and 1/8-inch Metal Columns in Packed Inlets
Using the figures on the next page as a guide:
1. Assemble a brass nut and graphite ferrule onto the liner/adapter.
2. Insert the adapter straight into the inlet base as far as possible.
3. Holding the adapter in this position, tighten the nut finger-tight.
4. Use a wrench to tighten the nut an additional 1/4-turn.
To install new swage-type nut and ferrules on the column, follow the procedure Preparing
Packed Metal Columns, earlier in this section. For metal columns with ferrules already
installed, continue with step 5.
5. Install the column into the inlet by tightening the column nut, assuming ferrule(s) are
already set (locked) onto the column (see Preparing Packed Metal Columns in this section).
Generally an additional 1/4-turn past finger-tight is sufficient for 1/8-inch columns. For
1/4-inch columns, an additional 3/4-turn is usually sufficient.
Use two wrenches in opposition, one on the column nut and the other on the liner body,
to prevent rotation of the liner while tightening the column nut.
Installing Columns 2-8
1/4-inch Metal Column, Packed Inlet
1/8-inch Metal Column, Packed Inlet
Inlet Fitting
Inlet Fitting
1/4-inch Ferrule
B
I
\
1/4-inch Metal Ferrule
i'
\
Back Ferrule
1
1/4-inch Nut
1
1/4-inch Nut
1
1/8-inch Liner
1/4-inch Column
1
LJ
Front Ferrule
fis
Back Ferrule
1/8-inch Nut
1/8-inch Column
Using Two Wrenches in Opposition to Tighten Column Fittings
Installing 1/4 and 1/8-inch Metal Columns in Packed Inlets
Installing Columns 2-9
Installing 1/4-inch Glass Columns in Packed Inlets
At the inlet end, there must be enough column left empty to prevent an inserted syringe needle
from contacting either the glass wool plug or column packing (at least 50 mm).
At the detector end, there must be at least a 40-mm empty section to prevent the bottom end of
the jet from touching either column packing or glass wool plug.
Because they are rigid, 1/4-inch packed glass columns must be installed simultaneously at both
the inlet and the detector. The procedure is identical at either end. For information on
detector column installation, refer to the appropriate section depending on the detector being
used.
Glass columns can be installed with either O-rings or nonmetallic ferrules. For O-ring
installation, we recommend using one O-ring with a front metal ferrule, reversed to provide a
flat surface for it to seal against.
Using the figures on the next page as a guide:
1. Assemble a brass nut, reversed metal ferrule, and O-ring onto both ends of the column.
If desired, an extra O-ring may be placed on the column before the nut. This protects the
column by preventing the nuts from dropping into the coiled portion of the column.
2. Insert the column into both the inlet and detector as far as possible. To clear the floor of
the oven, it may be necessary to start the longer end of the column into the inlet at a slight
angle.
3. Withdraw the column about 1 to 2 mm and tighten both column nuts finger-tight; the
degree to which the nut is tightened further depends upon the type of ferrule used:
•
For O-rings, finger-tight is usually sufficient.
•
For Vespel or graphite ferrules, raise the inlet, detector, and oven to operating
temperature, then use a wrench to tighten an additional 1/2-turn. Tighten further as
necessary to prevent leakage.
CAUTION
Over-tightening the column nut may shatter the column.
Installing Columns 2-10
1/4-inch Column, Packed Inlet
Inlet Fitting
•0'
Graphite O-ring
Reversed Brass Ferrule
1/4-inch Nut
Silicone O-ring
Recommended
Graphite O-ring
I
Silicone O-ring
I
1\
§
I
=,
I
1
Graphite, Vespel,
or
Graphitized Vespel
Ferrule
§
i
Alternative Installation Methods
Installing 1/4-inch Glass Columns in Packed Inlets
Installing Columns 2-11
Installing Capillary Columns in Packed Inlets
Using the figures on the next page as a guide:
1. Assemble a brass nut and graphite ferrule onto the liner/adapter.
2. Install a glass insert into the liner/adapter.
3. Insert the liner/adapter straight into the inlet as far as possible.
4. Holding the liner/adapter in this position, tighten the nut finger-tight.
5. Use a wrench to tighten the nut an additional 1/4-turn.
Hewlett-Packard capillary columns are wound on wire frames and mount on a pair of
brackets that slip into slots at the top of the oven interior.
The bracket has two positions from which to hang the column wire frame. Depending
upon frame diameter, use the position that best centers the column in the oven. Column
ends should come off the bottom of the frame, making smooth curves to inlet and detector
fittings. Avoid allowing any section of the column itself to come in contact with oven
interior surfaces.
6. Install on the column, a column nut (HP part no. 18740-20870) and ferrule. Note that
either a 1.0- or 0.5-mm id graphite ferrule may be used depending upon column outer
diameter.
Inserting the column through the nut and ferrule may contaminate the end of the column.
Prepare a fresh column end by the instructions given in Preparing Fused Silica Capillary
Columns in this section.
7. Position the column so it extends less than 2.0 mm from the end of the ferrule and column
nut (threaded end). Mark the column at a point even with the bottom of the nut
(hexagonal end). Typewriter correction fluid is a good marking material.
8. Insert column, ferrule, and nut straight into the inlet base. While maintaining the mark on
the column so as to be even with the bottom of the column nut, tighten the nut to
finger-tightness, then 1/4-turn more using a wrench.
9. While holding the spring to the right, slide the capillary liner insulation cup up over the
capillary nut. The insulation at the top of the cup should fit flush against the roof of the
oven.
10. Release the spring into the groove in the inlet liner.
Installing Columns 2-12
Column Hanger Position
Capillary Column, Packed Inlet
Inlet Fitting
n ,
t
«
Glass Insert
I'Liner
Marking the Column Position
1/4-inch
Ferrule
-4 -
Liner
Retainer
Nut
-2 CITL_
About 2 mm
Graphite
Ferrule
0 1
Capillary
Column
Nut
Capillary
Column
Capillary Liner
Insulation Cup
Paint Mark
Installing Capillary Columns in Packed Inlets
Installing Columns 2-13
Installing Capillary Columns in Split/Splitless Capillary Inlets
A specific inlet insert is required depending upon the particular sampling mode, split or
splitless. See "Installing Split/Splitless Capillary Inlet Inserts" in the this chapter, if not already
installed.
The following installation procedure assumes that the inlet is prepared properly to receive the
capillary column (e.g., that the correct insert is already installed).
Hewlett-Packard capillary columns are wound on wire frames and mount on a pair of brackets
that slip into slots at the top of the oven interior.
The bracket has two positions from which to hang the column wire frame. Depending upon
frame diameter, use the position that best centers the column in the oven. Column ends should
come off the bottom of the frame, making smooth curves to inlet and detector fittings. Avoid
allowing any section of the column itself to come in contact with oven interior surfaces.
Using the figures on the next page as a guide:
1. Install on the column a column nut (HP part no. 18740-20870) and ferrule. Note that
either a 1.0- or 0.5-mm id graphite ferrule may be used depending upon column outer
diameter.
Inserting the column through the nut and ferrule may contaminate the end of the column.
Prepare a fresh column end following instructions given in Preparing Fused Silica Capillary
Columns in this section.
2. Position the column so it extends approximately 4 to 6 mm from the end of the ferrule and
column nut (threaded end). Mark the column at a point even with the bottom of the nut
(hexagonal end). Typewriter correction fluid is a good marking material.
3. Insert column, ferrule, and nut straight into the inlet base. While maintaining the mark on
the column so as to be even with the bottom of the column nut, tighten the nut to
finger-tightness, then 1/4-turn more using a wrench.
Installing Columns 2-14
Column Hanger Position
Capillary Column
Split/Splitless Capillary Inlet
a,
8
Marking the Column Position
- 4-
Inlet Fitting
Graphite Ferrule
Capillary Column Nut
-2 Approx. 4 to 6 mm
—cm—;
Capillary Column
0=T
Paint Mark
Installing Capillary Columns in Split/Splitless Capillary Inlets
Installing Columns 2-15
Installing 1/4-inch Metal Columns in Flame lonization and
Nitrogen-Phosphorus Detectors
Nitrogen-Phosphorus Detectors: To avoid contamination of the active element upon receipt, do
not remove the seals until ready to connect the column and operate the detector. Failure to
observe this simple procedure may reduce the collector's effectiveness or possibly ruin the
active element.
To install new swage-type nut and ferrules on the column, follow the procedure Preparing
Packed Metal Columns, earlier in this section. For metal columns with ferrules already
installed, continue.
Using the figures on the next page as a guide:
Install the column into the inlet by tightening the column nut, assuming ferrule(s) are already
set (locked) onto the column (see Preparing Packed Metal Columns in this chapter). Generally
an additional 3/4-turn is usually sufficient.
Installing Columns 2-16
1/4-inch Packed Metal Column, FID/NPD
Inlet Fitting
Q
Front Ferrule
Back Ferrule
1
1/4-inch Nut
1/4-inch Column
Installing 1/4-inch Metal Columns in an FID and NPD
Installing Columns 2-17
Installing 1/8-inch Metal Columns in Flame lonization and
Nitrogen-Phosphorus Detectors
Nitrogen—Phosphorus Detectors: To avoid contamination of the active element upon receipt,
do not remove the seals until ready to connect the column and operate the detector. Failure to
observe this simple procedure may reduce the collector's effectiveness or possibly ruin the
active element.
Using the figures on the next page as a guide:
1. Assemble a brass nut and graphite ferrule onto the liner/adapter.
2. Insert the adapter straight into the detector base as far as possible.
3. Holding the adapter in this position, tighten the nut finger-tight.
4. Use a wrench to tighten the nut an additional 1/4-turn.
5. Install the column into the inlet by tightening the column nut, assuming ferrule(s) are
already set (locked) onto the column (see Preparing Packed Metal Columns in this section).
Generally an additional 1/4-turn is usually sufficient.
Use two wrenches in opposition, one on the column nut and the other on the liner body,
to prevent rotation of the liner while tightening the column nut.
Installing Columns 2-18
1/8-inch Packed Metal Column,
FID/NPD
Detector Fitting
1/4-inch Ferrule
1
1/4-inch Nut
1
1/8-inch Adapter
Using Two Wrenches in Opposition to Tighten
Column Fittings
a
LJ
<^3
Front Ferrule
Back Ferrule
1/8-inch Nut
1/8-inch Column
Installing 1/8-inch Metal Columns in an FID and NPD
Installing Columns 2-19
Installing Capillary Columns in Flame lonization and
Nitrogen-Phosphorus Detectors
Nitrogen-Phosphorus Detectors: To avoid contamination of the active element upon receipt, do
not remove the seals until ready to connect the column and operate the detector. Failure to
observe this simple procedure may reduce the collector's effectiveness or possibly ruin the
active element.
Assuming that the 0.011-inch capillary jet (HP part no. 19244-80560) is installed (if not, see
Chapter 9, "Preventive Maintenance" in the HP 5890 Reference Manual), proceed as follows:
Using the figures on the next page as a guide:
1. Assemble a brass nut and graphite ferrule onto the liner/adapter.
2. Insert the adapter straight into the detector base as far as possible.
3. Holding the adapter in this position, tighten the nut finger-tight.
4. Use a wrench to tighten the nut an additional 1/4-turn.
5. Install on the column, a column nut (HP part no. 18740-20870) and ferrule. Note that
either a 1.0- or 0.5-mm id graphite ferrule may be used depending upon column outer
diameter.
Inserting the column through the nut and ferrule may contaminate the end of the column.
Prepare a fresh column end following instructions given in "Preparing Fussed Silica
Capillary Columns" in this chapter.
6. GENTLY insert the column as far as possible into the detector (about 40 mm) until it
bottoms; do not attempt to force it further. Follow it with the ferrule and column nut.
7. Tighten the nut finger-tight, withdraw the column approximately 1 mm, and then tighten
the nut an additional 1/4-turn with a wrench.
8. Leak-test the installation at the column nut, both at ambient temperature and with the
oven, inlet(s), and detector(s) at operating temperatures. If necessary, tighten fitting(s)
further only enough to stop leakage.
Leak-detection fluids often leave contaminating residues. After each
application, the area checked should be rinsed with CH3OH (methanol)
and allowed to dry.
Installing Columns 2-20
Capillary Column, FID/NPD
Detector Fitting
1/4-inch Ferrule
P.
1/4-inch Nut
Capillary Column Adapter
Ferrule
Capillary Column Nut
Capillary Column
Installing Capillary Columns in FID and NPD
Installing Columns 2-21
Installing an 1/8-inch Metal Column in a
Thermal Conductivity Detector
To install new swage-type nut and ferrules on the column, follow the procedure Preparing
Packed Metal Columns, earlier in this chapter. For columns with ferrules already installed,
continue.
Using the figures on the next page as a guide:
Install the column into the inlet by tightening the column nut, assuming the ferrule(s) are
already set onto the column. An additional 1/4-turn is usually sufficient.
Installing Columns 2-22
1/8-inch Packed Metal Column, TCD
Detector Fitting
L_i
^3
Front Ferrule
Back Ferrule
1/8-inch Nut
1/8-inch Column
Installing a 1/8-inch Metal Column in a Thermal Conductivity Detector
Installing Columns 2-23
Installing a Capillary Column in a
Thermal Conductivity Detector
Using the figures on the next page as a guide:
1. Assemble a brass nut and graphite ferrule onto the liner/adapter.
2. Insert the adapter straight into the detector base as far as possible.
3. Holding the adapter in this position, tighten the nut finger-tight.
4. Use a wrench to tighten the nut an additional 1/4-turn.
5. Install on the column, a column nut (HP part no. 18740-20870) and ferrule. Note that
either a 1.0- or 0.5-mm id graphite ferrule may be used depending upon column outer
diameter.
Inserting the column through the nut and ferrule may contaminate the end of the column.
Prepare a fresh column end following instructions given in Preparing Fused Silica Capillary
Columns in this chapter.
6. GENTLY insert the column as far as possible into the detector until it bottoms; do not
attempt to force it further. Follow it with the ferrule and column nut.
7. Tighten the nut finger-tight, withdraw the column approximately 1 mm, and then tighten
the nut an additional 1/4-turn with a wrench.
8. Leak-test the installation at the column nut, both at ambient temperature and with the
oven, inlet(s), and detector(s) at operating temperatures. If necessary, tighten fitting(s)
further only enough to stop leakage.
Leak-detection fluids often leave contaminating residues. After each
application, the area checked should be rinsed with CH3OH (methanol)
and allowed to dry.
Installing Columns 2-24
Capillary Column
with Makeup Gas, TCD
Detector Fitting
Ferrule
1
1/8-inch Nut
TCD Makeup Gas
Adapter
Ferrule
Capillary Column Nut
Capillary Column
Installing a Capillary Column in a Thermal Conductivity Detector
Installing Columns 2-25
Installing a 1/4-inch Glass Column in an
Electron Capture Detector
Because they are rigid, 1/4-inch packed glass columns must be installed simultaneously at both
the inlet and the detector. The procedure is identical at either end. For information on inlet
column installation, refer to the appropriate chapter depending on the inlet being used.
Glass columns can be installed with either O-rings or nonmetallic ferrules. For O-ring
installation, we recommend using one O-ring with a front metal ferrule, reversed to provide a
flat surface for it to seal against.
Using the figures on the next page as a guide:
1. Assemble a brass nut, reversed metal ferrule, and O-ring onto both ends of the column.
If desired, an extra O-ring may be placed on the column before the nut. This protects the
column by preventing the nuts from dropping into the coiled portion of the column.
2. Insert the column into both the inlet and detector as far as possible. To clear the floor of
the oven, it may be necessary to start the longer end of the column into the inlet at a slight
angle.
3. Withdraw the column about 1 to 2 mm and tighten both column nuts finger-tight; the
degree to which the nut is tightened further depends upon the type of ferrule used:
•
For O-rings, finger-tight is usually sufficient.
•
For Vespel or graphite ferrules, raise the inlet, detector, and oven to operating
temperature, then use a wrench to tighten an additional 1/2-turn. Tighten further as
necessary to prevent leakage.
CAUTION
Overtightening the column nut may shatter the column.
Installing Columns 2-26
1/4-inch Packed Glass Column, ECD
Detector Fitting
-8-
Graphite O-ring
Reversed Brass Ferrule
I
1/4-inch Nut
Silicone O-ring
Recommended
Silicone O-ring
Graphite O-ring
I
I
1
1
I
1
Graphite, Vespel,
or
Graphitized Vespel
Ferrule
I'll
1
I
1/4-inch Packed Glass Columns, Alternative Installation Methods
Installing a 1/4-inch Glass Column in an Electron Capture Detector
Installing Columns 2-27
Installing a Capillary Column in an Electron Capture Detector
Using the figures on the next page as a guide:
1. Remove the cap of the makeup gas adapter.
2. Install a fused silica liner in the bottom half of the adapter.
3. Replace the cap of the makeup gas adapter. Tighten the cap hand-tight.
4. Insert the ECD adapter straight into the detector as far as possible and tighten the nut
finger-tight.
5. Use a wrench to tighten the nut an additional 1/4-turn.
6. Install on the column a column nut (HP part no. 18740-20870) and ferrule. Note that
either a 1.0- or 0.5-mm id graphite ferrule may be used depending upon column outer
diameter.
Inserting the column through the nut and ferrule may contaminate the end of the column.
Prepare a fresh column end following instructions given in "Preparing Fused Silica
Capillary Columns" in this chapter.
7. Measure 75 mm from the end of the column and mark the column. Typewriter correction
fluid is a good marking material. Gently insert the column into the detector followed by
the ferrule and column nut. Tighten the nut finger-tight. Position the column so the
75-mm mark is even with the end of the column nut. Tighten the nut an additional
1/4-turn with a wrench.
Installing Columns 2-28
Capillary Column
with Makeup Gas, ECD
Detector Fitting
1/4-inch Ferrule
n
Cap
1/4-inch Nut
ECD Capillary
Column Adapter
Fused Silica Liner
Ferrule
Capillary Column Nut
T
Capillary Column
75 mm
I
ECD Capillary
Column Adapter
Paint Mark
\
Installing a Capillary Column in an Electron Capture Detector
Installing Columns 2-29
Installing an 1/8-inch Metal Column in a
Flame Photometric Detector
To install new swage-type nut and ferrules on the column, follow the procedure Preparing
Packed Metal Columns, earlier in this chapter. For columns with ferrules already installed,
continue.
Using the figures on the next page as a guide:
1. Assemble a brass nut and graphite ferrule onto the liner/adapter.
2. Insert the adapter straight into the detector base as far as possible.
3. Holding the adapter in this position, tighten the nut finger-tight.
4. Use a wrench to tighten the nut an additional 1/4-turn.
5. Install the column into the inlet by tightening the column nut assuming ferrule(s) are
already set (locked) onto the column (see "Preparing Packed Metal Columns" in this
chapter). An additional 1/4-turn is usually sufficient.
Use two wrenches in opposition, one on the column nut and the other on the liner body,
to prevent rotation of the liner while tightening the column nut.
Installing Columns 2-30
1/8-inch Packed Metal Column, FPD
Detector Fitting
Using Two Wrenches in Opposition to Tighten
Column Fittings
1/4-inch Ferrule
1/4-inch Nut
1/8-inch Liner
Front Ferrule
Back Ferrule
1/8-inch Nut
1/8-inch Column
Installing an 1/8-inch Metal Column in a Flame Photometric Detector
Installing Columns 2-31
Installing a Capillary Column in a Flame Photometric Detector
Using the figures on the next page as a guide:
1. Assemble a brass nut and graphite ferrule onto the FPD capillary column adapter.
2. Insert the FPD adapter straight into the detector as far as possible and tighten the nut
finger-tight.
3. Use a wrench to tighten the nut an additional 1/4-turn.
4. Install on the column a column nut and ferrule. Note that either a 1.0- or 0.5-mm id
graphite feirule may be used depending upon column outer diameter.
Inserting the column through the nut and ferrule may contaminate the end of the column.
Prepare a fresh column end following instructions given in "Preparing Fused Silica
Capillary Columns" in this chapter.
5. Measure 162 mm from the end of the column and mark the column. Typewriter correction
fluid is a good marking material. Gently insert the column into the detector followed by
the ferrule and column nut. Tighten the nut finger-tight. Position the column so the
162-mm mark is even with the end of the column nut. Tighten the nut an additional
1/4-turn with a wrench.
This height may be optimized higher or lower depending on sample type and detector flow
rates. If the column is too high, it can be exposed to the detector flame. If the column is
too low, the sample can be exposed to some hot stainless steel which can result in slight
peak tailing.
Installing Columns 2-32
Brass Nut
FPD Capillary
Column Adapter
Graphite Ferrule
••
Capillary
Column Nut
162 mm
Paint Mark •
Installing a Capillary Column in a Flame Photometric Detector
Installing Columns 2-33
Contents
Chapter 3: Setting Heated Zone Temperatures
Operating Limits for Heated Zones
Setting Oven Temperatures
Displaying Oven Temperature
Examples
Setting Oven Temperature to 200"C
Setting Oven Equilibration Time to 1 Minute
Setting the Oven Maximum to 350°C
Using Cryogenic Oven Cooling
Programming Oven Temperatures
Examples
Setting Inlet and Detector Temperatures
Displaying Inlet and Detector Temperature
Example
Setting Inlet Temperature to 200°C
Setting Detector Temperature to 200°C
Setting Auxiliary Temperatures
3-3
3-4
3-4
3-5
3-5
3-5
3-5
3-6
3-8
3-9
3-13
3-13
3-14
3-14
3-14
3-15
3
setting I
^Temperatures
TEMPERATURE COWTBOL KEYS
Oven Control
- INIT
1
\W-UEJ
OVEN
TEMP
"INTA
TEMP
.
j
INJB
TEMP
———-|
INIT
TTIME_J
-——n
RATE
DETA
TEMP
FINAL
TIME
FINAL
VALUE
•
OVEN
EQUIB
TIME
DETB
TEMP
t
:
.
1
1
WSm
mi *
t
i
Heated Zone Control
Setting
Heated Zone Temperatures 3-1
Typical Display, Selpoinl And Current Value
ACTUAL
OVENTSMP
27*
SETPOINT
360
Note that the ACTUAL value is a measured quantity, while the SETPOINT value is userdefined: In this example, the setpoint value for oven temperature might recently have been
changed from 250 to 350 °C, and the oven is now heating to the new setpoint. Given sufficient
time for equilibration, ACTUAL and SETPOINT values become equal.
In addition to
in defining setpoint values,
sequences:
ENTER 1, which are used
]O are used in certain specific key
I and [°FF 1 add convenience in being able to switch on or off the oven,
and/or heated zones, without losing their current setpoint values.
Keys I A 1 and 1 B 1 are used in key sequences defining a multiple-ramp oven
temperature program: I A 1 as part of key sequences defining parameters for the
second ramp, I B ) as part of key sequences defining parameters for the third ramp.
Setting Heated Zone Temperatures 3-2
Operating Limits for Heated Zones
Valid Selpoint Ranges For Temperature Control Keys
Valid
Selpoint Range
Key
Oven Control
- 8 0 to 450
0 to 650.00
0.01 minute
Oven Control
0to70
0.1 /minute
Oven Control
re
Oven Control
0.01 minute
Oven Control
re
Oven Control
0.01 minute
Oven Control
re
re
re
re
re
Zone Control
OVEN TEMP
I
- 8 0 to 450
[
INITTEMP
^
f
INITTIME
^
(
FINAL TEMP _ 1
- 8 0 to 450
[
FINAL TIME
^
0 to 650.00
[
OVEN MAX
_1
[
EQUIB TIME
1
0 to 200.00
(
INJ A TEMP
1
0 to 400
(
INJ B TEMP
1
0 to 400
[
DETATEMP
1
0 to 400*
[
DETBTEMP
1
0 to 400*
(
AUX TEMP
NOTE:
Function
re
re
[
^1
In
Increments of
70 to 450
0 to 400
Oven Control
Zone Control
Zone Control
Zone Control
Zone Control
TOTA L run time will not exceed 650.00 minutes regardless of values entered
f o r C INITTIME 1 [ RATE 1 a n H l _ FINAL TIME I
*The valid setpoint range for a flame ionization detector is 0 to 450°C.
Setting Heated Zone Temperatures 3-3
Setting Oven Temperatures
Oven temperature may be controlled anywhere within the range of — 80 °C (with cryogenic
cooling using liquid N2) through 450 °C in increments of 1°C.
Oven temperature control keys include:
OVEN TEMP
To enter a constant temperature for the oven
EQUIB TIME
To enter a time for oven temperature to equilibrate
whenever oven temperature is modified
(Equilibration time begins when the actual oven temperature comes within 1°C of the oven temperature setting.)
OVEN MAX
To set an oven temperature maximum limit
Displaying Oven Temperature
Press [
OVEN TEMP
1 to display the current oven temperature.
Sample Display =
OVEN TEMP
The oven is switched on with key sequence: I
60
OVENTEMP~~J
SO {or OFF)
| ON ) I ENTER 1
The oven is also switched on by entering a new setpoint value; the new value replaces OFF or
the previous value.
Setting Heated Zone Temperatures 3-4
Examples
Setting Oven Temperature to 200 °C
Current oven temp = 100 °C
Display = I OVEN TEMP
Press:
[ OVENTEMPI
| 2 I
1 0 1 [ 0 I
100
100
I ENTER 1
The oven temperature will change from 100°C to 200°C and stabilize.
Setting Oven Equilibration Time to 1 Minute
Press:
[
EQUIBTIME~~1
I 1 1
I
• 1
I 0 1 1 0 1
1 ENTER 1
The oven equilibration time will be 1 minute.
Setting the Oven Maximum to 350 C
Press: IMa&il [
OVEN MAX
1 I 3 1 I 5 I I 0 1 [ ENTER I
The maximum temperature the oven can be set to is 350 °C.
The HP 5890 SERIES II verifies oven setpoints as they are entered; an appropriate message is
displayed when an entered setpoint is inconsistent with a previously defined setpoint.
Display =
OVEN MAXIMUM ss 350
In this case, an oven temperature greater then 350° C was attempted while the OVEN MAX is
set to 350°C.
Setting Heated Zone Temperatures 3-5
Using Cryogenic Oven Cooling
Oven temperature may be controlled below ambient when a cryogenic valve is present.
Cryogenic control setpoints are:
CRYO ON
To enable subambient control of the oven
CRYO OFF
To disable subambient cooling of the oven; the
default state for the cryogenic valve is OFF.
CRYO BLAST ON
To enable very fast cool-down time after a run
CRYO BLAST OFF
To disable very fast cooling of the oven
AMBIENT
Sets optimal temperature control for efficient use
of cryogenic fluid. (The default temperature
setting is 25 °C.)
CRYO FAULT ON/OFF
A fault occurs when the oven does not reach set
temperature after 17 minutes of continuous cryo
operation. The oven turns off and WARN:0VEN SHUT
OFF is displayed. Turning Cryo Fault OFF will disable
this feature.
CRYO TIMEOUT XXX MIN
A cryo timeout occurs when a run does not start
within a specified time (10 to 120 minutes) after the
oven equilibrates. Turning Cryo Timeout OFF will
disable this feature. Default is ON for 30 minutes.
When on, the cryogenic valve (if installed) operates automatically to obtain an oven temperature when there is demand for coolant to be supplied to the oven.
When cryogenic cooling is NOT needed, cryogenic valve operation MUST be turned off. If
this is not done, proper oven temperature control may not be possible, particularly at temperatures near ambient.
The Cryo Blast feature can operate together with or independently of Cryo On/Off. Cryo Blast
cools the oven faster AFTER a run than it normally would under normal cryogenic operation.
This allows the HP 5890 to become ready for the next run earlier than it would without cryo
blast on. This feature is useful when maximum sample throughput is necessary.
Setting Heated Zone Temperatures 3-6
Successively pressing the L CRYO PARAM J key scrolls through functions related to cryogenic
valve operation. To turn cryogenic operation on/off and cryogenic blast on/off, the following
key sequence is used:
or
HI
[
CRYO PARAM 1
[OFF]
| ON
To turn Cryo Blast operation on or off, the following key sequence is used:
ON I or I OFF]
iWaij
[
CRYO PARAM
1
SCROLL TO CRYO BLAST
Q5N_
An example key sequence to change the ambient temperature setting to 23°C is:
f
CRYO PARAM
SCROLL TO AMBIENT
Ambient temperature is setable to allow fine tuning of cryogenic operation. The default setting
is 25 °C and for most applications need not be changed. For more information about adjusting
the ambient cryogenic setting, see the HP 5890 SERIES II Reference Manual.
The following figure shows displays associated with disabling/enabling automatic cryogenic
valve operation.
Displays, Cryogenic Valve Operation
cmo
cmo
ACTUAL
SETPOINT
ACTUAL
SETPOINT
ACTUAL
SETPOINT
OH
OFF
CRYO FAULT ON
ACTUAL
1
SETPOINT
Cmo TIMEOUT 20 Mfn
Setting Heated Zone Temperatures 3-7
Programming Oven Temperatures
The oven temperature may be programmed from an initial temperature to a final temperature
(in any combination of heating or cooling) using up to three ramps during a run.
Oven temperature programming keys include:
INTT VALUE
The starting temperature of a temperature programmed run. This is also the temperature the oven
returns to at the end of a temperature programmed
run.
INIT TIME
The length of time the oven will stay at the starting
temperature after a programmed run has begun.
RATE
Controls the rate at which the oven will be heated or
cooled in degrees C/min. A temperature-programming rate of 0 halts further programming.
FINAL VALUE
Temperature the oven will reach at the end of a
heating or cooling temperature-programmed run.
FINAL TIME
The length of time the oven temperature will be
held at the final temperature of a temperatureprogrammed run.
Total elapsed time for a run cannot exceed 650 minutes. At 650 minutes, the run terminates
and oven temperature returns to the initial oven temperature. In isothermal operation
(RATE = 0), the instrument internally sets run time to the maximum of 650 minutes.
Setting Heated Zone Temperatures 3-8
Examples
A Single-Ramp Temperature Program: Programming oven temperature from 100 °C to 200 °C
at 10°C/min.
Current oven temp = 100°C,
Display =
OVEN TEMP
100
100
Example setpoinls for a single-ramp temperature program:
INIT VALUE
INITTIME
RATE
FINAL VALUE
FINAL TIME
100
2
10
200
1
Single-Ramp Temperature Program
FINAL
VALUE
RATE
FINAL
TIME
\
Cool-down
\ (Uncontrolled)
\
INIT
VALUE
\
INIT
TIME
EQUIB
\ _ T J M E _ Oven Ready
for Next Run
Run Time
Run Terminates
Automatically
Setting Heated Z o n e Temperatures 3-9
A TVo-Ramp Temperature Program: Oven temperature will be held at 100°C for 2 minutes,
then program from 100°C to 200°C at 10°C/min for the first ramp.
Oven temperature will be held at 200 °C for 2 minutes, then program from 200 °C to 250 °C at
5°C/min for the second ramp.
Example setpoints for a two ramp oven program:
1ST RAMP
2ND RAMP
INIT VALUE
INITTIME
RATE
FINAL VALUE
FINAL TIME
100
2
10
200
2
RATE A
FINAL VALUE
FINAL TIME
5
250
1
Two-Ramp Temperature Program
FINAL
VALUE A
RATE A
FINAL
VALUE
RATE,
Cool-down
(uncontrolled)
FINAL
TIME
EQUIB
\ _ _ _ _Oven Ready
for Next Run
INIT
VALUE
INIT
TIME
FINAL
Time A
Run Time
Run Terminates
Automatically
Setting Heated Zone Temperatures 3-10
A Three-Ramp Temperature Program: Oven temperature will be held at 100°C for 1 minute,
then program from 100°C to 200°C at 10°C/min for the first ramp.
Oven temperature will be held at 200 °C for 2 minutes, then program from 200 °C to 250° C at
10°C/min for the second ramp.
Oven temperature will be held at 250 °C for 2 minutes, then program from 250 °C to 300 °C at
10°C/min for the third ramp. Oven temperature will be held at 300°C for 1 minute before
returning to the initial starting temperature of 100 °C.
Example setpoints for a three-ramp oven program:
1ST RAMP
INIT VALUE
INIIT TIME
RATE
FINAL VALUE
FINAL TIME
100
1
10
200
2
2ND RAMP
RATE A
FINAL VALUE
FINAL TIME
3RD RAMP
10
250
2
RATE B
FINAL VALUE
FINAL TIME
10
300
1
Three-Ramp Temperature Program
FINAL
VALUE B>
Cool-down
I (uncontrolled)
INIT
VALUE
INIT
TIME
Run Time
I EQUIB
|_TJ_ME_
Oven Ready
for Next Run
Run Terminates
Automatically
Setting Heated Zone Temperatures 3-11
A Three-Ramp Temperature Program (with a controlled cool-down step): Oven temperature
will be held at 100°C for 1 minute, then program from 100°C to 200°C at 10°C/min for the
first ramp.
Oven temperature will be held at 200 °C for 2 minutes, then cool (controlled) from 200 °C to
150°C for the second ramp.
Oven temperature will be held at 150°C for 1 minute, then program from 150°C to 250°C at
10°C/min for the third ramp. Oven temperature will be held at 250°C for 2 minutes before
returning to the initial starting temperature of 100 °C.
Example setpoinl conditions for a three-ramp oven program:
2ND RAMP
1ST RAMP
INIT VALUE
INITTIME
RATE
FINAL VALUE
FINAL TIME
100
1
10
200
2
RATE A
FINAL VALUE
FINAL TIME
3RD RAMP
5
150
1
RATE B
FINAL VALUE
FINAL TIME
10
250
2
Three-Ramp Temperature Program with a Cooling Step
FINAL
VALUE B
FINAL
VALUE
RATE
INIT
VALUE
INIT
TIME
Cool-down
(controlled)
RATEB
FINAL
A
IL
TIME
flE
\ /
YRATE A
FINAL \
VALUE A *—=rr
FINAL
TIME A
Run Time
FINAL >
TIME B
Cool-down
(uncontrolled)
I EQUIB
I_TIME_
Oven Ready
for Next Run
Run Terminates
Automatically
Setting Heated Zone Temperatures 3-12
Setting Inlet and Detector Temperatures
Inlet and detector temperatures may be controlled anywhere from room temperature to 400°C.
Inlet and detector temperature control keys include:
INJ A TEMP
To set temperature for the inlet in the A position
INJ B TEMP
To set temperature for the inlet in the B position
DETATEMP
To set temperature for the detector in the A position
DETBTEMP
To set temperature for the detector in the B position
Displaying Inlet and Detector Temperature
Press [ INJ A TEMP ~j (or I INJBTEMP~1 ) to display the current inlet temperature.
100
Sample Display =
100
Press [ PET A TEMP ~1 (or L PET B TEMP ~*| ) to display the current detector temperature.
Sample Display = | OETATBMB9
100
100
An inlet or detector is switched on or off with key sequences:
( [
INJ A TEMP
1 or [
INJ B TEMP
1 \ [ ON | / | OFF |
(j
PETATEMP 1 o r [ DETBTEMP J ) [ ON ) / fOFF^
The inlet or detector is also switched on by entering a new setpoint value; the new value
replaces OFF or the previous value.
Setting Heated Zone Temperatures 3-13
Example
Setting Inlet Temperature to 200°C
Current inlet temp = OFF
Dis la
P y= Illllllilililiiilllillillllilll
Press:
([
INJ A TEMP
1
or [
INJ B TEMP
1 ) | 2 I
I 0 1
[ 0 I [ ENTER
The inlet temperature will change from OFF to 200 °C and stabilize.
Setting Detector Temperature to 200°C
Current detector temp = OFF
Display =
Press:
([
PET A TEMP "j o r
J)ET A TEMP
[ PET B TEMP
1 ) [ 2 1
38
I 0 1
[ 0 I
OFF
1 ENTER 1
The detector temperature will change from OFF to 200°C and stabilize.
Setting Heated Zone Temperatures 3-14
Setting Auxiliary Temperatures
AUX TEMP
AUX TEMP is usually used for heated valve compartment,
heated transfer line, etc.
INJATEMP
IN J B TEMP
Any of these keys may control an auxiliary heated zone
depending upon the instrument configuration.
DETATEMP
DET B TEMP
Instructions are provided in a separate envelope when a temperature control key has been
assigned to a heated zone other than the zone it identifies.
As an example, to set the AUX TEMP heated zone to 100 °C,
Setting Heated Zone Temperatures 3-15
Instrument Rear
Heated Zone Temperature Control
Key Assignments
INJA
TEMP
AUX
TEMP
Any of the keys
DETB
TEMP
DETA
TEMP
INJB
TEMP
, depending upon
which zones are unused.
Inlet Zone
B
Valve Zone
Detector Zone
Valve Box
INJA
TEMP
Setting Heated Zone Temperatures 3-16
B
DETB
TEMP
DETA
TEMP
Contents
Chapter 4: Setting Inlet System Flow Rates
>w'
Measuring Flow Rates
Using a Bubble Flow Meter
Required Adapters for Measuring Flow Rates
Changing the Packed Inlet Flow Ranges
Changing the Source Pressure
Setting the Packed Inlet Flow with Septum Purge
Manual Flow Control:
Electronic Pressure Control:
Setting the Split/Splitless Capillary Inlet Flow
Setting the Split Mode Flow
Manual Flow Control:
Electronic Pressure Control:
Setting the Splitless Mode Flow
Manual Flow Control:
Electronic Pressure Control:
Manual Purge Switching:
Automatic Purge Switching:
Displaying the Gas Flow Rate
Designating Gas Type
Using the Internal Stopwatch
4-1
4-2
4-4
4-5
4-5
4-6
4-6
4-7
4-9
4-11
4-11
4-12
4-18
4-18
4-19
4-21
4-21
4-25
4-25
4-27
4
Setting Inlet System Flow Rates
This chapter provides operating information for the following HP 5890 inlet systems:
• Septum-purged packed column inlet
• Split/splitless capillary inlet
Operating information for the Programmable Cool On-Column Inlet is provided in a separate
manual included with the HP 5890.
Measuring Flow Rates
Use a bubble flow meter to initialize all flows for the first time and to check them whenever the
system is changed in some way.
Bubble Flow Meter for Measuring Flow Rates
Setting Inlet System Flow Rates
4-1
Using a Bubble Flow Meter
A bubble flow meter with rate ranges of 1, 10, and 100 ml/min is suitable for measuring both
low flow rates (such as carrier gases) and higher flow rates (such as air for an FID).
A bubble flow meter is a very basic, reliable tool for measuring gas flow. It creates a bubble
meniscus across a tube through which the gas is flowing. The meniscus acts as a barrier and its
motion reflects the speed of the gas through the tube. Most bubble flow meters have sections of
different diameters so they can measure a wide range of flows conveniently.
1. Attach one end of the bubble flow meter adapter to the flexible gas-inlet line of the bubble
flow meter.
2. Attach the other end of the adapter to the detector outlet exhaust vent or other vent
through which you will measure flow.
3. Fill the bulb of the bubble flow meter with soapy water or leak detection fluid (such as
Snoop ).
4. Prepare the built-in stopwatch on the keyboard using the following keystrokes on its keypad:
Press: I
T|ME
1 up to three times.
The display on the oven module now displays zeroes for the time (t) and the reciprocal time
(1/t).
5. While holding the bubble flow meter vertically, squeeze and release the bulb to create a
meniscus in the bubble flow meter.
6. Press: I ENTER 1 to start the stopwatch when the meniscus passes the lowest line in the
bubble flow meter.
7. Press: I ENTER 1 to stop the stopwatch when the meniscus passes the upper line in one of the
tube sections.
Setting Inlet System Flow Rates
4-2
8. Calculate the flow rate in ml/min:
• If you stopped the meniscus at the first line, the flow rate is numerically equivalent to
the reciprocal time reading displayed on the oven module.
• If you stopped the meniscus at the second line, the flow rate is numerically equivalent to
10 times the reciprocal time reading displayed on the oven module.
• If you stopped the meniscus at the third line, the flow rate is numerically equivalent to
100 times the reciprocal time reading displayed on the oven module.
9. Press: 1 CLEAR I
an(j
repeat steps 5 through 8 at least once to verify the flow.
10. Start the makeup gas flow by turning the Aux Gas knob on the upper-left portion of the
oven front counterclockwise until the valve is in the open position.
11. Measure the total gas flow by repeating steps 5 through 8.
12. If the flow is not correct:
• Wait at least 2 minutes for the flow through the system to stabilize.
• Repeat the above procedure as necessary.
Note: If you use an FID, TCD, or NPD, use a small screwdriver to adjust the variable
restrictor at the center of the Aux Gas knob as necessary.
Setting Inlet System Flow Rates
4-3
Required Adapters for Measuring Flow Rates
In general, inlet system, or column, flow rates are measured at detector exhaust vents. Septum
purge and split flow rates for capillary inlet systems are measured at vents located on the front
of the flow panel. A rubber adapter tube attaches directly to an NPD, ECD, or TCD exhaust
vent tube.
A special flow-measuring adapter is supplied for an FID. Attach a bubble flow meter to the
FID flow-measuring adapter and insert it into the detector exhaust vent as far as possible. You
may feel initial resistance as the adapter's O-ring is forced into the detector exhaust vent. Twist
and push the adapter during insertion to ensure that the O-ring forms a good seal.
WARNING
TO MINIMIZE THE RISK OF EXPLOSION, NEVER MEASURE AIR AND H 2
TOGETHER. MEASURE THEM SEPARATELY.
Required Adapters for Measuring Gas Flow Rates
FID Use
NPD, TCD, and ECD Use
Setting Inlet System Flow Rates
4-4
Changing the Packed Inlet Flow Ranges
You may want to change the flow range of your inlet for a number of reasons. For example, if
you are using flows in the lowest 20 percent of a flow restrictor's range, the retention times of
your analysis might wander. By changing from a flow of 20 ml/min with a flow restriction range
of 0 to 110 ml/min to one with a range of 0 to 20 ml/min, you can eliminate this problem.
You can change the flow ranges in packed inlets by either:
• Changing the source pressure, or
• Changing the flow restrictor in the flow controller. For instructions on changing the flow
restrictor, turn to page 2-7 of the Site Prep/Installation Manual.
Changing the Source Pressure
You can increase the upper limit of flow from a flow controller by increasing the source
pressure. The following table lists the maximum flows for the standard flow controller for a
packed inlet with a 0 to 20 ml/min flow restrictor at five pressures. For maximum H2 flows, read
from the Helium Flow column.
Source Pressure (psi)
Nitroaen Flow (ml/min)
Helium Flow (ml/min)
40
50
60
70
80
20
24
28
32
36
21
25
28
32
35
Setting Inlet System Flow Rates 4-5
Setting the Packed Inlet Flow with Septum Purge
Use the following steps to set the packed inlet flow:
1. Set the oven and heated zone temperatures to the desired operating values.
Note: Never heat the column until the flow rates are set.
2. Turn off the detector (particularly an NPD or TCD), if it is not off already, until you set the
carrier flow rate.
Note: The detector signal can be assigned to an appropriate output channel.
3. Set the carrier source pressure to at least 275 kPa (40 psi) to ensure proper operation for
most applications.
Note: Carrier source pressure must be at least 105 kPa (15 psi) greater than the maximum
column head pressure.
4. Turn off any other support gases to the detector (such as H2, air, reference flow, or capillary
makeup gas) to permit independent measurement of column flow rate.
5. Your inlet is equipped with either manual or electronic flow control. Set the column head
pressure according to the appropriate section below.
Manual Flow Control:
Turn the mass flow controller counterclockwise as necessary to obtain the desired flow rate,
as measured with a bubble flow meter at the detector exhaust vent.
Setting Inlet System Flow Rates
4-6
Electronic Pressure Control:
a. Select the pressure units you would like to use.
To change the units, press: IliB&MI I 1 1 ( ENTER 1. Then press the number of the
corresponding unit you want to use:
b. The example below sets Inlet B (Injector B) pressure to 10 psi. Use the example to set
the pressure you have selected.
c. Press:
ENTER 1
WwmM [ INJBPRES
ACTUAL
EPP B
10.0
Sefs inlet B pressure to 10 psi.
SETPOINT
10.0
The GC display looks like this
Note: To keep the pressure constant through an oven ramp program, see chapter 10,
"Using Electronic Pressure Control."
6. Check the septum purge flow rate:
The septum purge flow is fixed. Although it is not adjustable, you should check the flow. Do
not cap off the flow from the purge vent.
Carrier Gas Type
Approx. Flow
H2
He
N2
Argon/Methane
1.2-2.2 ml/min
1.0-1.8
0.6-1.2
0.5-1.1
7. Recheck the column flow rate and adjust as necessary.
Setting Inlet System Flow Rates
4-7
Flow Panels Controlling Purged Packed Inlet
Manual Pressure Control
Pressure
Gauge
Mass Flow
Controller
Septum
Purge
Vent
Electronic Pressure Control
Septum
Purge
Vent
Setting Inlet System Flow Rates
4-8
Setting the Split/Splitless Capillary Inlet Flow
Set the linear velocity through the column when using capillary columns. Linear velocity is
controlled by pressure at the head of the column. Pressure required to obtain a particular
velocity depends primarily upon the bore (id) of the column, length of the column, and oven
temperature.
Hewlett-Packard fused-silica capillary columns are categorized according to their bores. The
table below lists the initial pressures for some capillary column bores and lengths.
The high pressure in each range is recommended as a starting point for most analyses and
yields a good compromise between efficiency and speed of analysis. The following sections
provide procedures to adjust head pressure to obtain any desired flow velocity through the
column.
Suggested Initial Head Pressures for Capillary Columns
Column
id (mm)
Column
Length (m)
Hydrogen Carrier Gas
Helium I Carrier Gas
kPa
0.20
0.20
0.20
12
25
50
0.32
12
25
50
29 -
0.32
0.32
0.53
0.53
10
30
8. 5 24. 0 -
85
psi
- 140
145 - 235
235 - 360
55
95
53
- 95
- 160
16
44
12
21
34
-
kPa
?1
34
52
4.27.914.0-
7.7
14
23
1.23.5-
2.4
6.3
48 -
84
- 145
145 - 230
87
17 33
60
32
- 60
- 105
5.0 14.0 -
9.7
27
psi
7 13 21 -
12
21
34
2.5 4.8 8.7 -
4.7
8.7
15
0.7 2.1 -
1.4
3.9
When using the 5-m x 0.53-mm id checkout column, the suggested pressure is 15 kPa (2.2 psi)
with He gas flow of 20 ml/min.
Setting Inlet System Flow Rates
4-9
Flow Panels Controlling Split/Splitless Inlet
Manual Pressure Control
Pressure
Gauge
Column Head
Pressure
Control
Total Flow
Controller
Septum
Purge
Vent
Split Vent
Electronic Pressure Control
Total Flow
Controller
Septum
Purge
Vent
Split Vent
Setting Inlet System Flow Rates
4-10
Setting the Split Mode Flow
WARNING
WHEN PERFORMING SPLIT SAMPLING AND USING HAZARDOUS CHEMICALS
AND/OR H 2 CARRIER GAS, VENT EFFLUENT FROM THE SPLIT VENT AND SEPTUM
PURGE VENT TO A FUME HOOD OR APPROPRIATE CHEMICAL TRAP.
To ensure proper operation, make sure the carrier source pressure is at least 105 kPa (15 psi)
greater than the selected column head pressure.
1. Use the following steps to set the initial column head pressure:
a. Set the column head pressure to 0:
Press:
IMM)
C INJ A PRES 1
(or [
INJBPRES 1^
| o |
[ ENTER 1
b. Increase the total flow control as necessary to obtain 100 ml/min measured at the split
vent.
c. Increase the column head pressure to obtain the selected pressure.
Your inlet is equipped with either manual or electronic pressure control. Set the column
head pressure according to the appropriate instructions below.
d. Set the oven and heated zone temperatures to the desired operating values. Make sure
the detector is turned on and its output signal is assigned to an appropriate channel (see
Chapter 6, "Controlling the Signal Output").
Manual Flow Control:
Turn the mass flow controller counterclockwise to establish flow. This will cause the
gauge pressure to increase.
Setting Inlet System Flow Rates
4-11
Electronic Pressure Control:
a. Select the pressure units you would like to use.
To change the units, press: E&;ii8M> I^ T' 1 1 ENTER 1. Then press the number of the
corresponding unit you want to use:
m =
kPa
b. The example below sets Inlet B (Injector B) pressure to 10 psi. Use the example to
set the pressure you have selected.
c. Press:
ENTER 1
INJ B PRES
ACTUAL
EPP B
Sets inlet B pressure to 10 psi
SETPOINT
10.0
10.0
The GC display looks like this
Note: To keep the pressure constant through an oven ramp program, see chapter 10,
"Using Electronic Pressure Control. "
2. Check the septum purge flow rate.
Excess carrier gas is vented through the septum purge vent. Although the septum purge vent
is not adjustable, you should check the flow. Do not cap off the flow from the purge vent.
Carrier Gas Type
Approx. Flow
H2
He
N2
Argon/Methane
3.5-6.0
1.5-3.5
1.5-3.5
1.5-3.5
Setting Inlet System Flow Rates
ml/min
ml/min
ml/min
ml/min
4-12
3. Set the linear velocity:
Using the timer feature (see "Using the Internal Stopwatch" in this chapter) and repeated
injection of an unretained component, adjust the column head pressure as necessary to
obtain the expected retention time for the desired linear velocity.
Linear velocity through the column is measured by injecting a sample containing an
unretained component (typically CH4 or air).
The observed retention time for the unretained component is compared to an expected
retention time (tr) calculated from the desired linear flow velocity (u) and the length of the
column:
Column Length (m)
tr (expected) (in min) = 1.67 —
Linear Flow Velocity (cm/sec)
4. Calculate the volumetric flow rate, if desired:
Use the following formula to simplify the calculation of volumetric flow through a capillary
column:
Volumetric Flow Rate (cm3/min) = 0.785
rj2|_
tr
where D is column internal diameter
L is column length
tr is retention time (min) of an unretained component, assuming the
desired linear velocity (u) has been obtained
This calculation becomes less accurate as pressure and gas compression are increased.
Setting Inlet System Flow Rates
4-13
The table below lists values of 0.785 x D2L for capillary column bores and lengths:
Values of 0.785 x D2L for Various Capillary Column Bores and Lengths
Nominal Length (mj
Nominal
id (mm)
12
25
50
0.20
0.377
0.785
1.57
0.25
0.589
1.22
2.45
0.32
0.965
2.01
4.02
0.53
2.65
5.51
11.0
0.75
5.30
11.0
22.1
5. Use a bubble flow meter connected at the detector exhaust vent to verify the calculated
volumetric flow rate through the column. (For bubble flow meter operating instructions, see
"Using a Bubble Flow Meter" earlier in this chapter.) Turn off any other gases to the
detector, such as makeup and/or support gases.
6. Use the following steps to verify that the inlet split flow is currently passing through the inlet
insert and will remain so throughout runs that are made in split sampling mode:
a. Display the current inlet split vent status:
Press:
[
PURGE/VALVE
1
[ A 1
(or
[ B )) ,
If OFF is displayed, press: I0N 1 to restore split flow through the inlet insert.
b. Display the time at which the split flow will be halted:
Press:
[
PURGE/VALVE
1
[ A \
(or
[ B \)
[ TIME 1
[OFF
c. Display the time at which the split flow will be restored:
Press: L
PURGE/VALVE
i
(or just press: I 0N 1 if
[
A
) (or 1 B 1) I
VALVE TIME
Setting Inlet System Flow Rates
4-14
TIME
1 I ON )
is already displayed).
d. Alternatively, set both times to 0.00 and turn on Purge A (or B):
Press: I ° 1 [ ENTER \ when the GC display reads:
ACTUAL
SETPOINT
PURGE VALVE A TIME ON
^v
y
7. Use the following steps to obtain the desired split ratio:
a. Measure the flow rate at the split vent using a bubble flow meter. For bubble flow meter
operating instructions, see "Using a Bubble Flow Meter" in this chapter.
b. Adjust the total flow control as necessary to obtain the flow rate required for the desired
split ratio.
c. Choose the split ratio appropriate for the analysis.
From the definition for the split ratio, use the following relationship to determine the
flow rate to be expected at the split vent for any desired split ratio:
Split Vent Flow Rate (ml/min) =
Volumetric Column Flow Rate (ml/min) x (Desired Split Ratio - 1)
Setting Inlet System Flow Rates
4-15
Split Flow Diagram for Electronic Pressure Control
Total Flow
Control
Capillary Inlet
Fixed Restrictor
for Septum Purge
104ml/mlrt
15
Purge Vent
3 ml/min Septum Purge Flow
: 3 ml/min
100 ml/min Split Flow
100 ml/min
' . Split Vent
Inlet Purge
Control Valve
ACTUAL
EPP B
10.0
SETPOINT
10.0
Electronic Pressure
Controlled through
Keyboard Entry
To Detector
1 ml/min
Column Flow
This example shows a 100:1 split ratio
100 ml/min Split Flow
1 ml/min Column Flow
Setting Inlet System Flow Rates
4-16
Split Flow Diagram for Manual Pressure Control
3 mt/min Septum PurgeHow
To Detector
1 ml/min
Column Flow
This example shows a 100:1 split ratio
100 ml/min Split Flow
1 ml/min Column Flow
Setting Inlet System Flow Rates
4-17
Setting the Splitless Mode Flow
WARNING
WHEN PERFORMING SPLITLESS SAMPLING AND USING HAZARDOUS
CHEMICALS AND/OR H 2 CARRIER GAS, VENT EFFLUENT FROM THE SPLIT
VENT AND SEPTUM PURGE VENT TO A FUME HOOD OR APPROPRIATE
CHEMICAL TRAP.
To ensure proper operation, make sure the carrier source pressure is at least 105 kPa (15 psi)
greater than the selected column head pressure.
Use these steps to set the splitless mode flow. This procedure assumes that detector gases are
connected, the system is leak-free, and the column and insert are properly installed.
1. Use the following steps to set the initial column head pressure:
a. Set the column head pressure and total flow controls to 0.
Press:
iWaiilB
[
INJ A PRES~~J
(Or [
INJ B PRES~^J ) [ o ) [ ENTER 1
Sets
the EPC
/ntefs
t0 0
b. Increase the total flow control as necessary to obtain 50 ml/min measured at the inlet
vent.
c. Increase the column head pressure to obtain the selected pressure.
Your inlet is equipped with either manual or electronic pressure control. Set the column
head pressure according to the following instructions for your inlet.
d. Set the oven and heated zone temperatures to the desired operating values. Make sure
the detector is turned on and its output signal is assigned to an appropriate channel (see
Chapter 6, "Controlling Signal Output").
Manual Flow Control:
Turn the mass flow controller counterclockwise to establish flow. This will cause the
gauge pressure to increase.
Setting Inlet System Flow Rates
4-18
Electronic Pressure Control:
a. To change the units, press: PISiiial
corresponding unit you want to use:
ENTER
| . Then press the number of the
U = psi
b. The example below sets Inlet B (Injector B) pressure to 10 psi. Use the example to
set the pressure you have selected.
c. Press:
' ENTER 1
M & S i l [ INJBPRES
ACTUAL
EPP 8
10,0
Sets inlet B pressure to 10 psi
SETPOINT
10.0
The GC display looks like this
Note: To keep the pressure constant through an oven ramp program, see chapter 10,
"Using Electronic Pressure Control. "
2. Check the septum purge flow rate if you have an EPC system.
Excess carrier gas is vented through the septum purge vent. Although the septum purge vent
is not adjustable, you should check the flow. Do not cap off the flow from the purge vent.
Carrier Gas Type
Approx. Flow
H2
He
N2
Argon/Methane
3.5-6.0 ml/min
1.5-3.5 ml/min
1.5-3.5 ml/min
1.5-3.5 ml/min
Setting Inlet System Flow Rates 4-19
3. Set the linear velocity:
Use the timer feature (see "Using the Internal Stopwatch" in this chapter) and make
repeated injections of an unretained component. Then adjust the column head pressure as
necessary to obtain the expected retention time for the desired linear velocity.
Linear velocity through the column is measured by injecting a sample containing an
unretained component (typically CH4 or air).
The observed retention time for the unretained component is compared to an expected
retention time (tr) calculated from the desired linear flow velocity (\x) and the length of the
column:
Column Length (m)
(expected) ( i n
min
) =
1
-67
Linear Row Velocity (cm/sec)
4. Use the following steps to set the splitless injection timetable:
Splitless injection is made possible by redirecting the inlet purge flow away from the inlet
insert at the time of injection. After injection, sufficient time is allowed for solvent and
sample components to reconcentrate at the head of the column. Then by redirecting the
purge flow back through the insert, solvent vapor within the inlet insert is purged.
There are two purge control channels, one for inlet A and one for inlet B.
a. To redirect the purge flow away from the column to allow for a splitless injection:
Press:
[
PURGE/VALVE
1
[ A | (Or I B | ) | O F F | _
Note: Flow through the insert at this point passes only through the column.
b. To restore the inlet purge flow:
Press:
C PURGE/VALVE
1
[ A ) (or I
Setting Inlet System Flow Rates 4-20
B
i)
I ON > ,
Manual Purge Switching:
Use the keyboard to switch the splitless solenoid valve on or off manually. Attempting to
switch the valve on (or off) when it is already on (or off) has no effect.
The figure below shows typical displays for current valve status and for verifying the timed
events table to switch the valve automatically during a run.
Typical Split/Splilless Inlet Purge Displays
ACTUAL
A
INL PURGE
ON
ACTUAL
INL PURGE
B
ON
PURGE
B
ON
ACTUAL
ACTUAL
B
PURGE
SETPOINT
OFF
SETPOINT
SETPOINT
1.50
SETPOINT
0.10
Automatic Purge Switching:
Use the steps below to switch the splitless solenoid valve on or off automatically once during
a run. The valve remains in its final state after termination of the run.
a. To put the inlet into the splitless mode:
Press: [ PURGE/VALVE 1
^O
(or r~B~>) fopn.
b. Set the on time value.
The on time value is the specific time delay after injection for the insert purging to
occur. The on time value depends upon the components, solvent, injection volume, flow
rate through the inlet, and internal insert volume (approximately 1 ml). Generally, an on
time value between 0.6 and 1.5 minutes is reasonable.
Press:
[
PURGE/VALVE
1
(or I
B
I)
1 TIME I I ON |
on
time value
I ENTER I .
Setting Inlet System Flow Rates
4-21
c. Set the off time value.
The purge A (or B) off time value should be somewhat less than the total length of the
time for the run. Inlet purge flow is switched off automatically just prior to the end of
the run to ensure that the inlet valve is in the correct state for the start of the next run.
off time value t ENTER
Press:
d. To display the time during the run when the purging will be halted:
Press:
e. To display elapsed time during the run when purging will be restored:
Press:
C
PURGE/VALVE
>
[ A \ (or I
B
I)
[ TIME 1
[ ON \ ,
Once the inlet purging event is displayed, you can enter a new elapsed time (to 0.01
minute or similar) at any time. Elapsed time to halt inlet purging must be prior to
injection (typically 0.00). Both on and off times are referenced to the start of the oven
program.
Note: Any entered value from 0.00 through 650.00 minutes is valid. However, the system
ignores an entered time greater than that of the run time itself and does not switch the
purge valve. The system also ignores the switch command if the programmed on and off
times are the same.
For information about EPC (constant pressure, optimizing splitless injection), see
chapter 10, "Using Electronic Pressure Control."
Setting Inlet System Flow Rates
4-22
Splitless Flow Diagram for Electronic Pressure Control
Purge A (or B) ON
Septum Purge
Vent
mmmmm 3 ml/min
a ml/mm Septum Purgejlow
^
soml/minjfiet Purge flow
Purge Control Valve
ACTUAL
EPP B
10*0
1O
»
%
'°
Electronic Pressure
Controlled through
Keyboard Entry
TO Detector
1 ml/min
Total Flow
Control
SETPOINT
Purge A (or B) OFF
Capillary Inlet
»wn»t/miiHntet Purge Flow
Purge Control Valve
TO Detector
Electronic Pressure
Controlled through
Keyboard Entry
Setting Inlet System Flow Rates
4-23
Splitless Flow Diagram for Manual Flow Control
Total Flow
Control
Purge A (or B) ON
Capillary Inlet
Septum Purge
Control
3 ml/min Septum Purge Flow
54 ml/mln
| i 3 ml/min
"Dd
SO ml/mln ntel Purge F)pi
;;;iiii||||li;; 50 ml/min
(£•
Split Vent
Purge Control Valve
Column Head
Pressure
Control
To Detector
1 ml/min
Total Flow
Control
Purge A (or B) OFF
Capillary Inlet
Septum Purge
Control
Septum Purge
Vent
54 ml/mln
53 ffil/mln —i—+•
T~H
3 ml/min
3 ml/min
50 ml/miit inlet Purge Fiow
wvw
Split Vent
Purge Control Valve
Column Head
Pressure
Control
To Detector
1 ml/min
Setting Inlet System Flow Rates 4-24
50 ml/min
Displaying the Gas Flow Rate
Note: If you have EPC, you will not have this feature.
i
^~*^
If electronic flow sensing (EFS) is installed in the carrier gas system to the inlet, you can display
total supply flow rate through the system. To display the total supply flow rate:
Press: (FLOW
(EFS cannot be used with EPC inlets.) Typical gas flow rate displays are shown below.
Typical Electronic Flow Rate Sensor Displays
ACTUAL
FUOW A
25.4
ACTUAL
NO
SETPOINT
SETPOINT
FLOW SENSOR
Designating Gas Type
To scale the displayed flow rate value properly, you must designate one of the four commonly
used gases. Select the appropriate gas type from the table below.
Defining Type of Gas to Be Monitored
Number
1
2
3
4
Gas Type
Preferred Use
He (Helium)
N 2 (Nitrogen)
H2 (Hydrogen)
Ar/Cfy (Methane in Argon)
TCD
General
Capillary
ECD
Setting Inlet System Flow Rates
4-25
Use the steps below to select one of these gases for a particular flow channel.
1. Press: I ^ow ) |~A"1 (or I~B~> ) to display flow A (or B).
2. Press: I
1
I , I 2 I , I 3 ) , or I 4 1 followed by t ENTER 1.
The current flow rate is displayed and scaled appropriately for the chosen gas type.
To use a gas other than the four standard gases listed above, select the standard gas (He, N2,
H2, or Ar-Me/CH4) closest in thermal conductivity to the gas being used.
WARNING
DO NOT PASS ANY CORROSIVE GAS THROUGH THE EFS.
The maximum usable range for H2 is 100 ml/min. If flow rates above 100 ml/min are used, a gas
other than He, N2, or AR/CH4 is being used, or maximum accuracy in displayed flow rate is
required, you may need to calibrate the EFS. See the HP 5890 Series IIReference Manual.
Setting Inlet System Flow Rates
4-26
Using the Internal Stopwatch
The stopwatch timer is useful for setting gas flow rates and measuring elapsed time between
events of interest. In stopwatch mode, both time (to 0.1 second) and reciprocal time (to
0.01 min" 1 ) are displayed simultaneously. Use the following steps to access the stopwatch.
1. Press: I
TIME
1 repeatedly until the stopwatch display appears.
2. Press: I ENTER > to start the stopwatch. Press: I ENTER 1 again to stop it.
3. Press: I CLEAR 1 to reset the stopwatch.
Time Display
Stopwatch Mode
ACTUAL
t = 0 :00. 0
SETPOINT
1/t = 0 . 0 0
Setting Inlet System Flow Rates
4-27
Contents
Chapter 5:
Operating Detector Systems
Displaying Detector Status
Turning a Detector On or Off
Monitoring Detector Output
Operating Detectors Using Electronic Pressure Control
Accessing Auxiliary Channels C through F
Zeroing the Pressure Channel
Setting Constant Pressure
Setting Pressure Ramps
Changing Pressure Ramps
Example of Setting Pressure Ramps
Verifying Pressure Ramps
Setting Capillary Makeup Gas Flow Rate
Exceptions to Makeup Gas Flow
If the Power FailsO
Shutting Down Each Day
5-2
5-3
5-4
5-5
5-6
5-7
5-8
5-9
5-9
5-10
5-11
5-12
5-12
5-15
5-15
Operating the Flame lonization Detector (FID)
Setting Up the FID for Operation
Setting the FID Flow for Packed Columns
Setting the FID Flow for Capillary Columns
Setting the Makeup Gas Flow Rate
Turning the FID On and Off
Igniting the FID Flame
5-16
5-17
5-19
5-21
5-26
5-27
5-28
Operating the Thermal Conductivity Detector (TCD)
Setting Up the TCD for Operation
Setting the TCD Flow for Packed Columns
Setting the TCD Flow for Capillary Columns
Setting the TCD Carrier Gas Type
Setting the TCD Sensitivity
Turning the TCD On and Off
Inverting the TCD Polarity
Using Single-Column Compensation (SCC)
Displaying the Column Compensation Status
Initiating a Column Compensation Run
Assigning Column Compensation Data
5-29
5-30
5-30
5-31
5-33
5-34
5-35
5-35
5-36
5-37
5-38
5-40
Operating the Nitrogen-Phosphorus Detector (NPD)
Setting Up the NPD for Operation
Conditioning the NPD Active Element (Bead)
Setting the NPD Active Element (Bead) Power
Setting the NPD Flow for Packed Columns
Setting the NPD Flow for Capillary Columns
Turning the NPD On and Off
Optimizing the Performance of the NPD
Avoiding Contamination
Preserving the Lifetime of the Active Element
5-42
5-43
5-44
5-45
5-47
5-49
5-52
5-53
5-53
5-54
Operating the Electron Capture Detector (ECD)
Requirements for USA Owners
Introduction
General Considerations
Temperature Effects
Gases
Columns and Flow Rates
Background
Setting Up the ECD for Operation
Setting the Carrier/Makeup Gas Selection Switch
Setting the ECD Flow for Packed Columns
Setting the ECD Flow for Capillary Columns
Testing for Contamination
Testing for Leaks
Testing for Radioactive Leaks (the Wipe Test)
5-56
5-57
5-58
5-59
5-59
5-59
5-60
5-60
5-60
5-61
5-62
5-63
5-66
5-67
5-67
Operating the Flame Photometric Detector (FPD)
Setting Up the FPD for Operation
Setting the FPD Flow for Packed Columns
Setting the FPD Flow for Capillary Columns
Turning the FPD On and Off
Igniting the FPD Flame
5-68
5-68
5-69
5-71
5-74
5-74
5
Operating Detector Systems
This chapter provides general and specific operating information for the five HP 5890 Series II
and HP 5890 Series II Plus GC detector systems:
• Flame ionization detector (FID)
• Thermal conductivity detector (TCD)
• Nitrogen-phosphorus detector (NPD)
• Electron capture detector (ECD)
• Flame photometric detector (FPD)
Note: The Series 530 \i column supplied with the HP 5890 must be conditioned before use.
This is done by establishing a flow of carrier gas at 30 to 60 ml/min through the column while
the column is heated at 250°C for at least 4 hours. Refer to the HP 5890 Series IIReference
Manual, "Preventive Maintenance."
Operating Detector Systems
5-1
Displaying Detector Status
To turn a detector on or off, or to display the current status, press: IDET1 IA 1 (or IB 1)
Pressing lpET ) I A 1 ( o r | B \ ) while using a TCD toggles the polarity between positive
and negative.
The following occurs when each detector is turned off:
FID:
The output signal and collector voltage are switched off. The flame, if already lit,
remains so until gas supplies are turned off.
NPD: The output signal, its collector voltage, and the current through its active element are
switched off.
ECD: The output signal is switched off.
TCD: The output signal, flow modulator valve, and filament current are switched off.
FPD: The output signal and high voltage are switched off. The flame remains lit until gas
supplies are turned off.
Typical Detector Status Displays
SETPOINT
z
iiiiliiiiiiiiiiiiii
o
ACTUAL
ACTUAL
SETPOINT
!••
iiiiiiiiiiiiiiliililliiiiiiiiili
ACTUAL
SETPOINT
iiiiiiiiifiiiiliiliiiilll
Operating Detector Systems 5-2
Turning a Detector On or Off
The TCD filament can be permanently damaged if gas flow through the
detector is off or interrupted while the detector is on. Make sure the
detector is off whenever changes/adjustments are made affecting gas
flows through the detector.
Once the desired detector is displayed, press I0N 1 to turn it on and I°FF1 to turn it off. The
change is immediately displayed.
Note that turning a detector off or on does not affect its zone temperature. Detector temperature is controlled separately through the temperature control key associated with the particular
heated zone (L DETATEMP~~J or I DETBTEMP"~J ). For more information, see chapter 3, "Setting
Heated Zone Temperatures."
Operating Detector Systems
5-3
Monitoring Detector Output
Knowing the detector output is particularly useful when you initialize the detector for
operation, for example, when you light the flame for an FID, set the power to an NPD active
element, or check noise (baseline frequency) for an ECD.
1. To display the detector output at any time, assign an output channel (signal 1 and/or
signal 2 if installed) to a particular detector (identified by its location, A or B).
Press: 1 SIG1 > ( o r t SIGg 1 ) IA 1 ( o r I B 1) [ ENTER
2. Display the signal level for the detector by pressing I SIG1
(or
3. Press: [ SIG 1 1 (or fSIG2 1) again to display the signal source assigned to the particular
output channel.
The figure below shows typical displays:
Typical Displays for Monitoring the Detector Output Signal
ACTUAL
!l!!!i!I§
SETPOINT
Iliiiiiiiiili mm m
ACTUAL
1
1
1
1
1
1
1
1
1
1
1
iiiiii
ACTUAL
liiiiiiiili liiiiiiiili N O T
SETPOINT
SETPOINT
INSWliii
When detector A or B is not installed, signal 1 or 2 will be undefined. If you try to set a
detector that is not installed, the display shows that it is not installed.
The display shows the signal in real time, reacting immediately to anything affecting detector
response. This provides a convenient method for monitoring detector output.
Operating Detector Systems
5-4
Operating Detectors Using Electronic Pressure Control
This section describes general operations for detectors with EPC. The next section describes
how to set flows for systems controlled manually or electronically.
Electronic pressure control allows you to control all auxiliary gases that are configured using
EPC from the keyboard of the HP 5890 GC. Electronic control is available on channels C
through F for auxiliary gases. The figure below shows the HP 5890 GC keyboard, including the
EPC keys that allow you to access channels C through F:
STOP
START
TABLE
ADD
PREVIOUS
NEXT
I
FLOW
PARAM
CRYO
PARAM
FLOW
OFF
I
I
1
AUXC
PRES
ZERO
AUXD
PRES
ATTN
AUXE
PRES
TCD
SENS
AUXF
PRES
I
c
J
;m m m
ENTER
CLEAR
CDICD CD CD
)!CD CD CD
CD CD CD
COL
C0MP1
I
Channels C through F
Operating Detector Systems
5-5
This section contains basic operating instructions for channels C through F, including:
• Accessing the auxiliary channels
• Zeroing the pressure channel for calibration
• Setting a constant pressure program
• Setting pressure ramps
• Changing pressure ramps
• Verifying pressure ramps
Accessing Auxiliary Channels C through F
The four EPC auxiliary channels are accessed through the existing GC keyboard by using the
following keys:
Press:
To Access:
Auxiliary EPC channel C
gold
Auxiliary EPC channel D
Auxiliary EPC channel E
Auxiliary EPC channel F
After accessing each channel, the GC display shows the channel you have selected and the
actual and setpoint values. For example, after accessing auxiliary EPC channel C, the GC
display might look like this:
ACTUAL
SETPOINT
10.0
10.0
Operating Detector Systems
5-6
Zeroing the Pressure Channel
When you zero the pressure, you are compensating for background pressure. The system is
zeroed when it is shipped, but you should check it periodically, especially when the ambient
laboratory temperature changes dramatically.
Note: You should zero the EPC channels 30 to 60 minutes after the system has heated up,
because changes in temperature may cause fluctuations while the instrument heats to its final
temperature.
To zero the channel accurately, all flow must be removed from the system before you enter the
offset value. For each channel, you will first set the channel to zero, and then enter the value
labeled "actual" as the offset. The following example zeroes channel C.
1. Turn off all inlet and detector gases.
2. Depressurize the inlet and detector gases to 0.0 psi.
3. Set the auxiliary EPC channel C pressure to zero:
SETPOINT
~B&
0.0
The GC display looks like this.
where value is the zero offset value shown on the GC display labeled "actual."
ACTUAL
I
P^.P
&2
SETPOINT
&0 1
The GC display looks like this.
Follow the same procedure to zero the remaining auxiliary EPC channels. Remember that
the system must be completely depressurized before entering the value labeled "actual."
5. To zero channel D:
a. Press: i M i f t
I B~\ { ^ 1
[~"|
\~o~\ [ ENTER 1
Set auxiliary channel D pressure to O.O.
b. Press:
The GC display looks like this.
Operating Detector Systems 5-7
6. To zero channel E:
a. Press: j j i p a j g f l [ COLCOMPI 1 I o 1 [
b. Press:
EsJiaaiii
I s \ [ ENTER 1
tiiiiii
1 I o 1 [ ENTER |
set auxiliary channel E pressure to O.O.
value I ENTER \ .
ACTUAL
SETPOINT
mm.
tiii
The GC display looks like this.
7. To zero channel F:
[
b. Press: tlgji^jsl
COLCOMP2
T |
I
1
[ ENTER 1
ACTUAL
1 I o 1 [ ENTER 1 Set auxiliary channel F pressure to O.O.
value [ENTER
SETPOINT
The GC display looks like this.
Setting Constant Pressure
To set constant pressure for each of the four auxiliary channels, (where value is the desired
constant pressure value):
Press:
PPii;8l I A ) value [ ENTER 1 for EPC channel C.
Press:
EsSsa&S]) I B \ value 1 ENTER 1 for E P C channel D .
Press:
i i & i l l C COLCOMPI ^
value
t ENTER 1 for EPC channel E.
Press:
MmM
value
[ ENTER 1 for EPC channel F.
[
COLCOMP2
1
Note: To enter a constant pressure for a run, the initial time in the program must be as long as
(or longer than) the run time.
After setting the constant pressure for each channel, the GC display shows the channel
you have selected and the actual and setpoint pressure values. For example, if you set EPC
channel C to 60, the GC display looks like this:
ACTUAL
GPP C
60,0
SETPOINT
60.0
Operating Detector Systems 5-8
Setting Pressure Ramps
To set pressure ramps for each of the four auxiliary channels (where value is the setpoint value
for the specific part of the ramp):
To set the program for EPC channel C:
INIT VALUE
RATE 1 value
1
value
[ ENTER 1 [
I ENTER 1 [ FINAL VALUE j
value
INIT TIME ~ 1
1 ENTER 1 [
value
FINAL TIME
t ENTER
I
value
1 ENTER 1
To set the program for EPC channel D:
Press: MS&83
RATE |
B~\
value
[
INIT VALUE
1
value
[ ENTER |
1 ENTER 1 [ FINAL VALUE \
[
INIT TIME
value
I ENTER |
[
Value
[ ENTER
value
[ ENTER 1 [
1
Value
FINAL TIME
( ENTER
1
Value
1 ENTER
value
[ ENTER
value
1 ENTER
To set the program for EPC channel E:
Press: &§*«;§]
COL COMP1 ~ 1
RATE 1 value
[
INIT VALUE
1
[ ENTER 1 [ FINAL VALUE 1
INIT TIME
FINAL TIME
1
To set the program for EPC channel F:
Press:
MiSSill
I COLCOMP2"1
[ RATE 1 value
[
INIT VALUE ~~1 value
1 ENTER 1 [ FINAL VALUE \
value
[ ENTER
1 ENTER
INIT TIME ~ ~ 1 Value
FINAL TIME ~~1
Value
[ ENTER
[ ENTER [
Changing Pressure Ramps
To change pressure ramps for each of the four auxiliary EPC channels, follow the procedure for
setting pressure ramps and enter new values for any of the variables.
Operating Detector Systems 5-9
Example of Setting Pressure Ramps
This example shows how to enter a pressure ramp to program the gases for a detector that is
installed in the A position and controlled by auxiliary channel D.
1. To access auxiliary channel D:
SETPOINT
10.0
D
10.0
The GC display looks like this.
2. Enter a pressure program for auxiliary channel D:
a. Press: [
INITVALUE
1 40 [ ENTER 1 to set an initial pressure of 40 psi.
b. Press: [ INIT TIME 1 5 [ ENTER 1 to maintain the initial pressure for 5 minutes.
c. Press: 1 RATE I 10 1 ENTER 1 to increase the pressure by 10 psi per minute.
d. Press: [ FINAL VALUE ^
100 [ ENTER 1 to set a final pressure of 100 psi.
e. Press: [ FINAL TIME 1 io [ ENTER 1 to maintain the final pressure for 10 minutes.
The system will now ramp the pressure as shown below:
Operating Detector Systems 5-10
Verifying Pressure Ramps
To verify pressure for each of the four auxiliary channels, access the pressure channel to display
the actual and setpoint pressure values. For example:
Press: mmmm U J J to verify the pressure for auxiliary EPC channel C.
to vent
ACTUAL
SETPOINT
$0,0
The GC display looks like this.
Operating Detector Systems
5-11
Setting Capillary Makeup Gas Flow Rate
Capillary makeup gas is the gas that you add to the detector to compensate for the low carrier
gas flow rates used for capillary columns. Low carrier gas flow must be compensated for
because detectors are designed to operate best with a carrier flow rate of at least 20 ml/min,
which is typical of packed-column GC applications. Carrier flow rates less than 10 ml/min
(typically for capillary GC applications) require capillary makeup gas to ensure a total flow rate
(carrier plus makeup) of at least 20 ml/min.
For the ECD, capillary makeup gas should be used even with HP Series 530 \x capillary columns
because the detector requires high total flow rate (at least 25 ml/min).
Exceptions to Makeup Gas Flow
The TCD requires a total flow rate of only 5 ml/min (with about 15 ml/min TCD reference
flow). For the FID, TCD, NPD, and FPD, HP Series 530 \i capillary columns may be used
without capillary makeup gas as long as the carrier flow rate is between 10 and 20 ml/min. Some
loss of detector sensitivity may occur at lower flow rates.
For the FID, NPD, and FPD, makeup gas is added directly to hydrogen within the detector
flow manifold. For an ECD or TCD, it is added into the column gas stream via a capillary
makeup gas adapter fitted into the detector column inlet.
Operating Detector Systems
5-12
To set the makeup flow rate supply pressure for capillary makeup gas to about 276 kPa (40 psi):
1. Make sure the column and makeup gas fittings (if used) are properly installed.
2. Turn off all gas flows through the detector except the carrier flow.
3. Adjust the column flow to the desired value for the detector and column. Measure the flow
at the detector exit with a bubble flow meter.
4. Use the following instructions to enter the makeup gas values for either manual or EPC
systems:
Manual Pressure Control
a. Set supply pressure for capillary makeup gas to about 276 kPa (40 psi).
b. Open the auxiliary gas on/off valve. Use a small screwdriver to turn the variable
restrictor at the center of the on/off valve as necessary to obtain the desired total flow
rate (column plus makeup).
Variable Restrictor Adjustment
Variable Restrictor
Variable Restrictor
Operating Detector Systems
5-13
Electronic Pressure Control:
a. Set the supply pressure to the auxiliary EPC channel to 40 psi.
b. Open the Aux gas (makeup gas) on/off valve completely. You will use the auxiliary EPC
pressure to control the auxiliary gas flow rate. Be sure to open the needle valve fully by
turning it clockwise with a screwdriver.
c. Select the pressure units you would like to use.
To change the units, press: M6iS;sl 1 1 I [ ENTER 1. Then press the number of the
corresponding unit you want to use:
d. The example below sets Inlet B (Injector B) pressure to 10 psi. Use the example to set
the pressure you have selected.
e. Press:
P P a l l i FINJBPRES 1 | 1 1 | o 1 [ ENTER!
ACTUAL
EPP B
lOtf
Sets inlet B pressure to 10 psi.
SETPOINT
10,0 I
The GC display looks like this
Note: To keep the flow constant through an oven ramp program, see chapter 10, "Using
Electronic Pressure Control."
f. Adjust the makeup gas pressure to the detector as necessary to obtain 30 ml/min total
flow rate (column plus makeup).
5. Refer to the appropriate detector section to initialize the detector for operation.
Operating Detector Systems
5-14
If the Power Fails
If the power fails frequently, turn off the detector whenever it is not in use.
Note: When a detector is turned on after being off, it must be given time to stabilize before it
can be used at high sensitivity. The baseline will drift until the detector reaches equilibrium.
When power is restored after a power failure, the detector recovers to the same state as when
the power failed. The active element is restored to "on" if it was on before the power failure.
If the gases used to light the FID or FPD are controlled with EPC, the flow will go to zero when
the power fails and return to setpoint when restored. You will need to relight the flame after
the power is turned on. For auxiliary EPC, the GC returns to the setpoints it had before the
power failed.
Shutting Down Each Day
On a daily basis, use the steps in the following procedure to shut down the detector:
1. In most cases, leave the detector on and at operating temperature to avoid a long equilibration time at startup.
2. Leave the carrier flow on to protect the column(s). For extended shutdown periods, cool the
oven to room temperature, and then turn the carrier flow off.
3. With EPC applications, you can reduce the gas flows to conserve gas and still have the
detector lit and ready.
Note: For more information about the Gas Saver application, see chapter 10, "Using the
Gas Saver Application."
4. With the ECD, you may want to reduce the sensitivity by lowering the temperature to
prolong its lifetime. For extended shutdown periods, cap off the column interface and leave
a small amount of makeup gas flowing through the system.
Operating Detector Systems
5-15
Operating the Flame Ionization Detector (FID)
The flame ionization detector (FID) responds to compounds that produce ions when burned in
an H2-air flame. These include all organic compounds, although a few (such as formic acid and
formaldehyde) exhibit poor sensitivity. This selectivity can be advantageous—for example,
when used as solvents, H2O and CS2 do not produce large solvent peaks.
Compounds Producing Little or No Response
Permanent gases
Nitrogen oxides
Silicon halides
H20
NH 3
CO
C0 2
CS2
02
CCI4
The system is linear for most organic compounds from the minimum detectable limit through
concentrations greater than 107 times the minimum detectable limit. Linear range depends on
each specific compound and is directly proportional to sensitivity of the FID toward the given
compound.
For maximum sensitivity, optimize the flows using standard samples containing components of
interest in expected concentrations. Use the standard to experiment with different carrier, air,
and H2 flow rates, and determine the flow rates giving maximum response.
Operating Detector Systems
5-16
FID
Optimum Response Hydrogen versus Carrier Flow
50
(156)
—
40
(132)
—
30
(107)
—
20
—
tt
Hydrogen Flow
[ml/min or kPa]
(78)
i
i
i
i
20
30
40
50
1
60
Carrier Flow (N2), ml/min
In general, where sample components of interest are in high concentration, increased air flow
may be necessary (up to 650 ml/min). Where components of interest are in low concentration,
reduced air flow rates are acceptable (375 to 425 ml/min).
Setting Up the FID for Operation
To set up the FID for operation, you must do the following:
• Set the flow (for either packed or capillary columns)
• Set the detector flow rates
• Turn on the detector
• Ignite the flame
FID
Operating Detector Systems
5-17
Hydrogen Flow Rate versus Pressure
80 —
60 —
Hydrogen Flow
[ml/min]
syZ
/
40 —
•'/sy
s
y'/>
20 —
I
50
T
100
150
I
200
I
250
Pressure (kPa)
Air Flow Rate versus Pressure
800 —
600 —
Air Flow
[ml/min]
400 —
200 —
100
200
300
400
500
Pressure (kPa)
Operating Detector Systems
5-18
FID
Setting the FID Flow for Packed Columns
The gas flow rates given in this section ensure good, reliable detector behavior for most
applications. To optimize detector behavior for a specific application, use a standard sample
matched to the application and experimentally try other flow rates.
WARNING
FLAME IONIZATION DETECTORS USE H 2 GAS AS FUEL. IF H 2 FLOW IS
ON AND NO COLUMN IS CONNECTED TO THE DETECTOR INLET
FITTING, H 2 GAS CAN FLOW INTO THE OVEN AND CREATE AN
EXPLOSION HAZARD. INLET FITTINGS MUST HAVE EITHER A
COLUMN OR A CAP CONNECTED AT ALL TIMES THAT H 2 IS SUPPLIED
TO THE INSTRUMENT.
Note: Depending upon the column type used and the analyses to be performed, you may have
to change the jet in the FID.
Use the steps in the following procedure to set the FID flow in a packed column. This
procedure assumes that detector support gases are connected, the system is leak-free, the
correct jet is installed, and a column is installed.
1. Close the Aux Gas on/off valve. This controls the makeup gas.
2. Set the column flow rate to 30 ml/min. Because the procedure for setting column flow rate
depends on the column installed and the inlet system used, refer to the appropriate inlet
system information in Chapter 4.
3. Set the oven and heated zones to the desired operating temperatures.
4. Gently close the on/off controls for H2 and air by turning them clockwise.
5. Using the flow rate versus pressure figures (shown in this section) and the carrier gas flow
rate, set supply pressures for H2 and air to obtain the correct flow rates (30 ml/min of H2
and 430 ml/min of air are correct for most applications).
You can set H2 and air flow rates simply by setting their respective pressures. However,
if flow rates need to be verified, continue with this section using the bubble flow meter.
Otherwise, open the H2 and air on/off valves by turning them fully counterclockwise, and
proceed to "Igniting the Flame" later in this section.
FID
Operating Detector Systems
5-19
6. Use the following steps to set the H2 flow rate to 30 ml/min:
a. Attach a bubble flow meter to the FID collector.
WARNING
TO MINIMIZE RISK OF EXPLOSION WHEN USING A BUBBLE FLOW
METER, NEVER MEASURE AIR AND H 2 TOGETHER. MEASURE THEM
SEPARATELY.
b. Open the H 2 on/off valve by turning it counterclockwise. Measure the total flow rate
(column plus H2) through the detector.
c. Adjust the H2 pressure to the detector to obtain a total flow rate (column plus H2) of
about 30 ml/min.
d. Close the H2 on/off valve.
7. Use the following steps to set the air flow rate to 400 ml/min:
a. Open the air on/off valve by turning it counterclockwise. Measure the total flow rate
(column plus air) through the detector.
b. Adjust the air pressure to the detector to obtain a total flow rate (column plus air) of
about 430 ml/min.
8. Remove the bubble flow meter from the FID collector.
9. Open the H2 on/off valve. Proceed to "Igniting the Flame" later in this chapter.
Operating Detector Systems 5-20
FID
Setting the FID Flow for Capillary Columns
WARNING
FLAME IONIZATION DETECTORS USE H 2 GAS AS FUEL. IF H 2 FLOW IS
ON AND NO COLUMN IS CONNECTED TO THE DETECTOR INLET
FITTING, H 2 GAS CAN FLOW INTO THE OVEN AND CREATE AN
EXPLOSION HAZARD. INLET FITTINGS MUST HAVE EITHER A
COLUMN OR A CAP CONNECTED AT ALL TIMES THAT H 2 IS SUPPLIED
TO THE INSTRUMENT.
Note: Depending upon the column type used and the analyses to be performed, you may have
to change the jet in the FID.
The following table and graph show the optimal flow rates at which to control your FID.
FID
Operating Detector Systems 5-21
Typical Pressure versus Flow for FID Flow Reslrictors
Values computed using ambient temperature of 21 °C and pressure of 14.56 psi
FID Makeup
HP pn 19243-60540
Green and Red Dots
Flow Restrictor
FID Hydrogen
HP pn 19231-60770
Red Dot
Pressure
kPa
69.0
137.9
206.8
275.8
344.7
413.7
482.6
551.6
620.5
689.5
FID Air
HP pn 19231-60610
Brown Dot
Flow (ml/min)
psig
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
Nitrogen
Helium
Hydrogen
6.4
15.0
26.0
39.0
53.0
69.0
86.0
104.0
123.0
143.0
7.2
17.0
29.0
44.0
61.0
80.0
100.0
122.0
150.0
178.0
18.0
44.0
77.0
116.0
162.0
211.0
264.0
322.0
383.0
445.0
Air
65.0
157.0
273.0
410.0
561.0
726.0
900.0
1084.0
= Recommended calibration points for using EPC with the HP 3365 ChemStation
FID Restrictors
1000
500
Air/
^Hydrogen
/
400
800
/
/
/
300
600
/
200
-Helium
•Nitrogen
/
100
400
^
200
*
* —
20
Operating Detector Systems
40
5-22
60
80
Pressure (psig)
100
120
FID
Use the steps in the following procedure to set the column flow in a capillary column. This
procedure assumes that the detector support gases are connected, the system is leak-free, the
correct jet is installed, and a column is installed.
1. Set the column flow to the desired rate. Because the procedure for setting column flow rate
depends on the column installed and the inlet system used, refer to the appropriate inlet
system information in chapter 4.
2. Set the oven and heated zones to the desired operating temperatures.
3. Adjust the carrier and makeup gas flow rate (column plus makeup) through the detector to
at least 30 ml/min.
4. Use the following steps to set manually or verify the H2 flow rate to approximately
30 ml/min:
WARNING
TO MINIMIZE RISK OF EXPLOSION WHEN USING A BUBBLE FLOW
METER, NEVER MEASURE AIR AND H 2 TOGETHER. MEASURE THEM
SEPARATELY.
^w^
a. Attach the bubble flow meter to the FID collector.
b. Open the H2 on/off valve by turning it counterclockwise. Measure the total flow rate
(column plus makeup plus H2) through the detector.
c. Adjust the H2 pressure to the detector to obtain a total flow rate (column plus makeup
plus H2) of about 60 ml/min.
d. Close the H2 on/off valve.
5. Use the following steps to set the air flow rate to 400 ml/min:
a. Open the air on/off valve by turning it counterclockwise. Measure total flow rate
(column plus makeup plus air) through the detector.
i
b. Adjust the air pressure to the detector to obtain a total flow rate (column plus makeup
plus air) of about 400 ml/min.
FID
Operating Detector Systems
5-23
6. Remove the bubble flow meter from the FID collector.
7. Open the H2 on/off valve and ignite the flame.
8. Use the following instructions to enter the makeup gas values for either manual or
electronic systems.
Manual Pressure Control:
a. Set the supply pressure for the capillary makeup gas to about 276 kPa (40 psi).
b. Open the Aux gas (makeup gas) on/off valve by turning it counterclockwise.
c. Use a small screwdriver to turn the variable restrictor at the center of the on/off valve as
necessary to obtain 30 ml/min total flow rate (column plus makeup).
Electronic Pressure Control:
a. Set the supply pressure to the auxiliary EPC channel to 40 psi using the keyboard.
b. Open the Aux gas (makeup gas) on/off valve. Turn the variable restrictor fully
counterclockwise. Then adjust the pressure to set the desired flow rate.
c. Select the pressure units you would like to use.
To change the units, press: tiiP&ia I 1 I [ ENTER 1. Then press the number of the
corresponding unit you want to use:
d. With auxiliary EPC, makeup gas can be controlled through auxiliary pressure channels
C, D, E, or F from the keyboard. The example below sets the auxiliary channel C
pressure to 10 psi.
Press:
EtsSoi&sl I
A
1 I 1 \ I ° 1 [ ENTER )
ACTUAL
£PP C
1^0
Sets auxiliary channel Cpressureto 10 psi.
SETPOINT
10.0
The GC display looks like this.
Note: To keep the pressure constant through an oven ramp program, see chapter 10,
"Using Electronic Pressure Control."
e. Adjust the makeup gas pressure to the detector as necessary to obtain 30 ml/min total
flow rate (column plus makeup).
Operating Detector Systems
5-24
FID
9. Gently close the on/off controls for H2 and air by turning them clockwise.
10. Use the flow rate versus pressure graphs shown earlier in this chapter and the carrier gas
flow rate to set the supply pressures for H2 and air. Set the supply pressures to obtain the
correct flow rates. (30 ml/min of H2 and 400 ml/min of air are correct for most applications.)
Generally, you can set H2 and air flow rates simply by setting their respective pressures. For
an explanation of the relationship of flow to pressure in an EPC system, see chapter 10,
"Using Electronic Pressure Control."
Flow Panel for Controlling FID Operation
On/Off Valve,
Air
On/Off Valve,
H2
FID
Ignitor Button
(press to ignite)
On/Off Valve,
Capillary Makeup Gas
Operating Detector Systems
5-25
Setting the Makeup Gas Flow Rate
Detectors are designed to operate best with a carrier flow rate of at least 20 ml/min, which is
typical of packed-column GC applications. Carrier flow rates of less than 10 ml/min (typically
capillary GC applications) require capillary makeup gas to ensure a total flow rate (carrier plus
makeup) of at least 20 ml/min.
FID sensitivity depends on the ratio of H2 to carrier flow (or carrier plus makeup gas for
capillary columns). Use the procedure described in the following section to obtain maximum
sensitivity.
You can set makeup flow rate manually or electronically. In both cases, good laboratory
practice suggests that you calibrate the system with a bubble flow meter.
To set the makeup flow rate, set the supply pressure for capillary makeup gas to about 276 kPa
(40 psi):
1. Make sure the column and makeup gas fittings (if used) are properly installed.
2. Turn off all gas flows through the detector except the carrier flow.
3. Adjust the column flow to the desired value for the detector and column. Measure the flow
at the detector exit with a bubble flow meter.
4. Use the following instructions to enter the makeup gas values for either manual or
electronic systems.
Manual Pressure Control:
a. Set the supply pressure for the makeup gas to about 276 kPa (40 psi).
b. Open the Aux gas (makeup gas) on/off valve by turning it counterclockwise.
c. Use a small screwdriver to turn the variable restrictor at the center of the on/off valve as
necessary to obtain the desired total flow rate (column plus makeup).
Operating Detector Systems
5-26
FID
Electronic Pressure Control:
a. Set the supply pressure to the auxiliary EPC channel to 40 psi using the keyboard.
b. Open the Aux gas (makeup gas) on/off valve. Turn the variable restrictor fully counterclockwise. Then adjust the pressure through the keyboard to set the desired flow rate.
c. Select the pressure units you would like to use.
To change the units, press: Pl®3;*il 1 1 1 I ENTER I . Then press the number of the
corresponding unit you want to use:
d. The example below sets the auxiliary channel C pressure to 10 psi.
Press:
E i & i & M I A | 1 1 I [ o 1 [ ENTER 1
ACTUAL
SETPOINT
10,0
10.0
Sets auxiliary channel C pressure to 10 psi
The GC display looks like this
Note: To keep the flow constant through an oven ramp program, see chapter 10, "Using
Electronic Pressure Control."
e. Adjust the makeup gas pressure to the detector as necessary to obtain 30 ml/min total
flow rate (column plus makeup).
Turning the FID On and Off
After the FID flows have been set, you can turn on the detector electronics.
To turn the FID on, press:
IDETI
1 A ) (or I
B
l ) | ON l
To turn the FID off, press: (PET! (~A~> (or (~B~> ) [OFF!
FID
Operating Detector Systems 5-27
Igniting the FID Flame
This procedure assumes that detector support gases are connected, the system is leak-free, the
correct jet is installed, a column is installed, and the carrier gas and detector support gases have
been set and verified at the detector exhaust vent.
1. Open the air, H2, and makeup gas on/off valves.
Note: When using He as the capillary makeup gas, it may be necessary to turn off the
makeup gas flow temporarily until the flame is lit.
2. Before pressing the ignitor button, enter the following:
(^^SIGJJ / O r [ SIB 2 1 \ l A I Cor I B | \ [ ENTER )
[ SIG 1 1 frirl
SIG2 1 )
3. Press the ignitor button.
Note: You can light the FID flame regardless of whether the detector is electronically
on or off.
The displayed FID signal level will be in the range from 0 to 0.3 pA. When the flame lights, the
displayed signal increases to some greater steady value (for example, 10 pA), indicating that the
detector is active. The precise value depends upon the column and operating conditions. Turn
makeup gas on if necessary.
You may also test for ignition by holding a cold, shiny surface (such as a chrome-plated wrench)
over the collector exit. Steady condensation indicates that the flame is lit.
Operating Detector Systems
5-28
FID
Operating the Thermal Conductivity Detector (TCD)
This section assumes that all detector support gases are connected, leak-free, and that a column
is installed.
The TCD filament can be permanently damaged if gas flow through the
detector is interrupted while the filament is operating. Make sure the
detector is off whenever changes and adjustments are made affecting
gas flows through the detector.
Also, exposure to O 2 can permanently damage the filament. Make sure
the entire flow system associated with the TCD is leak-free and that
carrier/reference gas sources are uncontaminated before turning on the
detector. Do not use Teflon tubing, either as column material or as gas
supply lines, because it is permeable to O2.
When measuring TCD flow rates, attach a bubble flow meter directly to
the detector exhaust vent using a small piece of rubber tubing as an
adapter.
Note: When measuring TCD flow rates, a bubble flow meter is attached directly to the detector
exhaust vent using a small piece of rubber tubing as an adapter. For convenience, the HP 5890
provides a stopwatch feature (see chapter 4, "Using the Internal Stopwatch").
Flow Panel Controlling TCD Operation
On/Off Valve,
Capillary Makeup Gas
On/Off Valve,
Reference Gas
TCD
Operating Detector Systems 5-29
Setting Up the TCD for Operation
To set up the TCD for operation, you must do the following:
• Set the flow (for either packed or capillary columns).
• Set the carrier gas type.
• Set the sensitivity.
• Turn on the TCD.
This section will also show you how to:
• Invert TCD polarity.
• Use single-column compensation (SCC).
Setting the TCD Flow for Packed Columns
The gas flow rates given in this section ensure good, reliable detector behavior for most
applications. To optimize detector behavior for a specific application, use a standard sample
matched to the application and experiment with other flow rates.
Use the steps in the following procedure to set the TCD flow in a packed column. This
procedure assumes that detector support gases are connected, the system is leak-free, and a
column is installed.
1. Set the detector zone temperature to the desired value (30 to 50 °C greater than the
maximum oven temperature to prevent sample condensation).
Press:
[ PET A TEMP 1
(Or
[ PET B TEMP 1 )
temp value
1 ENTER >
2. Set the column flow rate to 30 ml/min. Because the procedure for setting column flow rate
depends on the column installed and the inlet system used, refer to the appropriate inlet
system information in chapter 4.
Note: When measuring column flow rate, make sure the reference gas flow through the
detector is turned off (clockwise).
Operating Detector Systems
5-30
TCD
3. Use the following steps to set the reference gas flow rate.
Note: A good guideline is to set the reference flow rate at 1.5 times the column flow rate.
a. Open the on/off valve for the TCD reference gas flow by turning it counterclockwise.
b. Use a small screwdriver to turn the variable restrictor at the center of the TCD reference
gas on/off valve as necessary to obtain the desired flow rate (45 ml/min is correct when
total flow is 30 ml/min).
4. If not already done, set the carrier gas type and detector sensitivity as discussed later in this
chapter.
Setting the TCD Flow for Capillary Columns
Use the steps in the following procedure to set the TCD flow in a capillary column. The gas
flow rates given in this section ensure good, reliable detector behavior for most applications. To
optimize detector behavior for a specific application, use a standard sample matched to the
application and experiment with other flow rates.
1. Set the detector temperature to the desired value (30 to 50 °C greater than the maximum
oven temperature to prevent sample condensation).
Press: [ PET A TEMP 1
(or
C PET B TEMP l
)
temp value
1ENTER 1
2. Set the column flow to 1 to 2 ml/min. Because the procedure for setting column flow rate
depends on the column installed and the inlet system used, refer to the appropriate inlet
system information in chapter 4.
Note: When measuring column flow rate, make sure the reference gas flow through the
detector is turned off (clockwise).
3. Set the makeup gas so that the total flow rate (column plus makeup) through the detector is
5 ml/min. Turn off the reference gas while making this measurement.
When you use makeup gas, you should push the column all the way up into the detector and
then pull it out approximately 1 mm. However, when you use a relatively high flow rate (and
no makeup gas), the column should be only 1 to 2 mm above the ferrule. If you want to
position the column all the way up for maximum inertness, then continue to use makeup gas
and set it to 1 to 2 ml/min.
Because a portion of the column passes through the TCD heated block and into the cell
itself, do not set the zone temperature for the TCD greater than the maximum temperature
allowed for the column. A higher zone temperature may cause column bleed.
TCD
Operating Detector Systems
5-31
4. Use the following instructions to enter the makeup gas values for either manual or
electronic systems. You can also control the TCD reference gas using the same steps used
to control the makeup gas.
Manual Pressure Control:
a. Set the supply pressure for capillary makeup gas to about 276 kPa (40 psi).
b. Open the Aux gas (makeup gas) on/off valve for TCD makeup gas flow by turning it
counterclockwise.
c. Use a small screwdriver to turn the variable restrictor at the center of the TCD makeup
gas as necessary to obtain 5 ml/min.
After the makeup gas is adjusted, the reference gas should be at least three times the
total flow rate from the column plus makeup. Therefore, if the column plus the makeup
flow is 5 ml/min, the reference flow equals 15 ml/min.
d. Open the on/off valve for the TCD reference gas flow by turning it counterclockwise.
e. Use a small screwdriver to turn the variable restrictor at the center of the TCD reference
gas on/off valve as necessary to obtain 15 ml/min.
Electronic Pressure Control:
a. Set the supply pressure to the auxiliary EPC channel to 40 psi using the keyboard.
b. Open the Aux gas (makeup gas) on/off valve. Turn the variable restrictor fully counterclockwise. Then set the pressure through the keyboard to get the desired flow rate.
c. Select the pressure units you would like to use.
To change the units, press: EiiPMI I 1 1 [ ENTER 1. Then press the number of the
corresponding unit you want to use:
[ a 1 = bar
d. The example below sets the auxiliary channel C pressure to 10 psi.
Press:
isj$&feijl I
A
1 I
1
1 C°~i [ ENTER"}
ACTUAL
SETPOINT
10,0
10.0
Sets auxiliary channel C pressure to 10 psi
The GC display looks like this
e. Adjust the makeup gas pressure to the detector as necessary to obtain 30 ml/min total
flow rate (column plus makeup).
Operating Detector Systems
5-32
TCD
5. Set the reference gas flow rate:
a. Open the on/off valve for the TCD reference gas flow by turning it counterclockwise.
b. Use a small screwdriver to turn the variable restrictor at the center of the TCD reference
gas on/off valve as necessary to obtain the required flow.
6. If it is not already done, set the carrier gas and detector sensitivity as discussed in the
following sections.
Setting the TCD Carrier Gas Type
To optimize the detector sensitivity with respect to the carrier gas used, a switch is provided on
the TCD signal board that is accessed at the top of the instrument under the top right cover.
FILAMENT
LEADS
TEMP
SENSOR
LEADS
GAS
TYPE
4 Nj,Ar
He, 11
«
SEE MANUAL
TO DISCONNECT
TCD
TCD
Operating Detector Systems
5-33
1. Locate the switch and place it in the position appropriate for the carrier gas used (either
N2, Ar, or He, H2).
2. To ensure the full dynamic range for the TCD, the reference gas (and capillary makeup gas,
if used) must be the same as the carrier gas. Using different gases results in baseline offset.
The TCD filament can be permanently damaged if gas flow through the
detector is interrupted while the detector is on. Make sure that the
detector is off whenever changes and adjustments are made affecting
gas flows through the detector.
Setting the TCD Sensitivity
Two sensitivity (signal amplification) settings are available through the keyboard. The highsensitivity setting increases sensitivity (area counts observed) by a factor of 32 and is usable in
applications where component concentrations are less than 10 percent. Components that are
more concentrated may exceed the output range for the TCD, causing flat-topped peaks. If this
occurs, use the low-sensitivity setting instead.
You can change the sensitivity setting at any time without turning the detector off. Changing
the setting has no effect upon filament lifetime. To set the TCD sensitivity from low to high:
Press: [iipgigl [DET| | A ) ( o r I B ) ) |OFF| to set the TCD sensitivity to low.
Press: Plisiaili IDET) [ A 1 (or I
B
1) I °" I to set the TCD sensitivity to high.
For information on how to change TCD sensitivity during a run, see chapter 7, "Making a
Run."
Operating Detector Systems
5-34
TCD
Turning the TCD On and Off
The TCD filament can be permanently damaged if gas flow through the
detector is interrupted while the detector is on. Make sure the detector is
changi
off whenever changes/adjustments
are made affecting gas flows
through the detector.
I ,
^"^
After TCD flows have been set, the detector may be turned on.
To turn the TCD on, press: IDETI I A 1 ( o r I B ) ) | ON ) .
To turn the TCD off, press: [PET! (~A~1 (or fB~l) 1W).
Allow about 1/2-hour for thermal stabilization (after the oven and zones achieve desired
setpoint values) before using the TCD.
Inverting the TCD Polarity
^•""/
For information on inverting the TCD signal polarity, refer to chapter 6, "Controlling Signal
Output."
TCD
Operating Detector Systems
5-35
Using Single-Column Compensation (SCC)
Because the TCD operates with only a single column, which is the analytical column,
single-column compensation (SCC) is strongly recommended to achieve optimum baseline
stability, particularly in temperature-programmed operation.
Alternatively, if two TCDs are installed, conventional dual-column compensation may be
performed by defining the output signal as A-B or B-A so as to output a different signal from
the two detectors. This assumes that the two detectors are operated using identical columns,
temperatures, and flow rate conditions.
The HP 5890 allows you to perform a chromatographic blank run (run made with no sample
injected) and stores the data as a baseline profile. The baseline profile must be consistent from
run to run so it can be subtracted from the sample run data to remove baseline drift (usually
caused by column bleed).
Note: Single-column compensation data is valid only for a specific detector and column
combination, operating under defined temperature and gas flow rate conditions. Invalid results
will occur if conditions by which blank run data is collected are different from conditions used
to collect sample run data.
Two separate profiles may be stored as designated by L COLCOMPII and [ OOLCOMP2 j . For
example, you may store one each for two different detectors or two profiles for the same
detector (using different chromatographic conditions).
Note: The 1 STOP 1 key is always active during a column compensation run if you need to
abort the run at the HP 5890 GC.
Operating Detector Systems
5-36
TCD
Displaying the Column Compensation Status
The status of column compensation data is displayed by pressing either i COLCOMPI~^ or
[ COLCOMP2 J x h e figure below shows examples:
Typical Column Compensation Status Displays
(Equivalent displays are possible
for COMP 2 and/or detector B)
ACTUAL
|
COUP 1
|
COMP
-
NO OATA
ACTUAL
1
-
DATA O K
ACTUAL
SETPOINT
A
|
SETPOINT
A
|
SETPOINT
liiliii! •iiiiiiiiiiiii
HSSSSV
ACTUAL
|
COMP 1
WRONG
TIME
No baseline profile data is presently
stored for detector A in COMP 1 .
Valid baseline profile data is presently
stored for detector A in COMP 1 .
Change in baseline slope exceeds
maximum value permitted.
Column compensation data may not be
valid.
SETPOINT
A
|
Column compensation run aborted
prematurely via t STOP I
Column compensation data may
not be valid.
In each display, COMP 1 or COMP 2 echoes the key pressed (L COLCOMPI 1
A or B indicates the assigned detector.
TCD
Or
[ COLCOMP2 1 ) .
Operating Detector Systems 5-37
Initiating a Column Compensation Run
After entering the oven temperature program to be used for later sample runs, a column
compensation run is initiated by first pressing either [ COLCOMPI~"1 o r [ COLCOMP2~~1 to
display current column compensation status and to designate where the new baseline profile is
to be stored.
•
If the desired detector (A or B) is displayed, the column compensation run is initiated
simply by pressing I ENTER 1
•
If the wrong detector is displayed, press either A or B to assign the desired detector;
then press t ENTER > to initiate the column compensation run.
•
I * \ followed by I ENTER 1 initiates two parallel column compensation runs, using the same
oven temperature program and storing a baseline profile for each of the assigned detectors
simultaneously.
This option is useful for sample analyses made using different detectors and/or columns but
using identical temperature programs.
Note: A device connected via the remote start/HP 5890 ready cable that is started from the
HP 5890 by a normal analytical run is not started by a column compensation run.
Additional details concerning functions available at the remote receptacle are found in the
HP 5890 Series II Site Prep and Installation Manual.
Messages listed in the next figure are displayed either while a column compensation run is in
progress or if there is a problem preventing the compensation run from starting.
Operating Detector Systems
5-38
TCD
Typical Column Compensation Message Displays
ACTUAL
|
GOMP 1
BLANK
RUN
ACTUAL
|
INVALID
DURING
RUN
ACTUAL
TEMP
1
PROGRAM
SETPOINT
[iiiiiii
Illlllj
ACTUAL
HOT
SETPOINT
NO
DETECTOR
SETPOINT
1
FOUND
ACTUAL
|
TCD
1NVAUD
IK
1
INSTALLED
ACTUAL
|
i
The oven is not on. Once the oven is
switched on, the column compensation
run begins automatically when the oven is
equilibrated at its initial temperature setpoint.
SETPOINT
ACTUAL
| OETA
I
Displayed if an attempt to start a column
compensation run is made while a sample
run is in progress. No column
compensation run is performed.
SETPOINT
OVSN NOT ON
| MO
Comp run in progress. In this example, data
from detector A is stored as COMP 1
(accessed via i CQLCQMPI~J).
SETPOINT
ACTUAL
|
|
SETPOINT
A
COMP
SETPOINT
RUNt
l
An oven temperature program is not defined:
nonzero I RATE l setpoint value(s) must be
entered. The temperature program defined
should be that used for sample runs. No
column compensation run is performed.
Chosen detector (either A or B) not
switched on. No column compensation run
is performed.
Chosen detector (either A or B) not present.
No column compensation run is performed.
No detector(s) present. No column
compensation run is performed.
Occurs if entering new oven temperature
program setpoints is attempted during a
column compensation run. Entries are
ignored. Also occurs if an attempt is made to,
start a column compensation run while one
is already in progress. The one in progress
continues to normal completion.
Operating Detector Systems
5-39
A column compensation run terminates automatically at the completion of its oven temperature program. Any existing baseline profile is erased as data for the new baseline profile is
collected and stored.
Note that the oven temperature program for a column compensation run follows setpoint
values for initial time, rate, and final time as in an analytical run. Data is stored, however, only
for rate and final time portions of the temperature program.
A sample run cannot be started via ( START 1 while a column compensation run is in progress.
Press: t ST0P E to abort a column compensation run when the baseline profile stored is
probably not valid (because the oven temperature program will not have reached the final
temperature setpoint). A message WRONG TIME is displayed to indicate that a mismatch has
occurred between the expected length of time for the run versus the actual time.
Assigning Column Compensation Data
After baseline data for a given detector is stored as either COMP 1 or COMP 2, the column
compensation data must be assigned to a specific detector signal. During a run, the
compensation data is subtracted from run data for the same detector.
The following key sequence assigns such baseline-corrected data to a particular output channel:
| ) [
Operating Detector Systems
5-40
- I I COL COMP 1 1
( o r [ COLCOMP2 1 ) [ ENTER | .
TCD
The figure below illustrates the display confirming the assignment:
Typical Display for Column Compensation
ACTUAL
SIGNAL
1
A
-
COMP
SETPOINT
1
Note: No internal verification is given by the HP 5890 to ensure that compensation data
collected on a given detector is assigned later to be subtracted from the same detector via the
above key sequence. If you get strange baseline behavior from subtracting compensation data:
• Compensation data itself is suspected.
• Data acquired from a different detector has been assigned.
• Chromatographic conditions used for sample analyses are different from those used for the
original column compensation run.
I ,
After you assign a particular output channel, sample analyses are performed in the usual
manner, the only difference being that the observed baseline should be relatively free of drift.
TCD
Operating Detector Systems
5-41
Operating the Nitrogen-Phosphorus Detector (NPD)
The nitrogen-phosphorus detector (NPD) uses a jet and collector similar to the FID. However,
the collector contains a small alumina cylinder coated with a rubidium salt (the active element),
which is heated electrically, creating a thermionic source. In this environment, nitrogen and
phosphorus containing organic molecules are ionized. The detector collects the ions and
measures the resulting current.
As with an FID, an NPD requires hydrogen and air, but at lower flows. Therefore, normal
FID-type ionizations are minimal, as is response to compounds not containing nitrogen or
phosphorus. Thus, the detector is both sensitive to and selective of compounds containing
nitrogen and/or phosphorus.
The electrical power for heating the active element is supplied through a toroidal transformer
located inside the NPD cover. The toroidal transformer secondary winding is connected
directly to the collector/active element assembly. The electrical heating current passes directly
through the small platinum wire that is also used to position the active element inside the
collector.
The active element of the NPD operates in a very delicate thermal balance that depends on
several different variables. The magnitude of the response of the NPD is a function of the
temperature of the active element and of the active zone around the active element itself.
Because of this temperature dependence, the output of the detector is very sensitive to
anything that affects the temperature of this active zone. Important variables and their effects
include the following:
• Increasing detector temperature increases the active element temperature and the response.
• Increasing the electrical power to the active element increases both the temperature of the
active element and the response.
• Increasing the hydrogen flow increases the temperature of the active element as well as the
size of the active zone around the active element; both effects result in increased response.
• Increasing the air flow to the detector normally cools the active element slightly and
decreases the response. (The change in temperature from altering the air flow is much less
than the change from altering the hydrogen flow.) Increasing the air flow also decreases the
residence time of a given peak in the active zone of the active element and decreases
response.
Operating Detector Systems
5-42
NPD
* Increasing the carrier gas flow cools the active zone slightly and decreases the residence
time of a component in the active zone, which decreases the response.
A hydrogen flow rate that is too high may cause a true flame around the active element. This
would severely overheat the active element and destroy the specific response. An air flow rate
that is too low may quench the background response of the active element, resulting in a
reequilibration time that is too long to establish a proper background response (negative
solvent peaks kill the active element).
Setting Up the NPD for Operation
To set up your NPD, you must do the following:
• Set the flow (for either packed or capillary columns).
• Condition the active element (bead).
• Set the active element power.
• Turn on the NPD.
Flow Panel Controlling NPD Operation
On/Off Valve,
Air
On/Off Valve,
H2 (Hydrogen)
NPD
On/Off Valve,
Capillary Makeup
Gas
Operating Detector Systems
5-43
Conditioning the NPD Active Element (Bead)
Condition the NPD active element (bead) when you install a new element or when the detector
has been turned off for a period of time. Conditioning removes water that may have been
absorbed into the active element from humidity in the air. If the active element is electrically
heated too rapidly, the rubidium coating on the active element can fracture and ruin the
collector.
This section assumes that the detector support gases are connected, the system is leak-free, the
correct jet is installed, and a column is installed.
1. Set and turn on the carrier and detector gases.
2. Turn the active element power control fully counterclockwise to set the power to 000.
Note: The locking lever immediately below the control knob is locked in the right-most
position and unlocked in the left-most position.
3. Turn off the power to the detector and the active element by pressing:
4. Set the oven temperature to 50 °C.
5. With the carrier and detector gases flowing, raise the temperature of the detector's
isothermal zone to 220 °C. Allow the collector to condition for at least 30 minutes under
these conditions.
Note: If your detector is exposed to high humidity, condition new collectors for a longer
period (overnight).
After the active element has been dried, initiate the specific NPD response by setting the
power to the active element.
Operating Detector Systems
5-44
NPD
Setting the NPD Active Element (Bead) Power
NPD Active Element (Bead) Power Control
The following procedure sets the correct operating temperature for the active element.
Operating at a temperature higher than the recommended range produces greater sensitivity at
the expense of increased noise and reduced element lifetime with no increase in minimum
detectable limit.
The temperature of the active element in the NPD collector is controlled by a 10-turn rotary
control located below the keyboard. A mechanical counter (000 through 999) registers the
position of the control.
NPD
Operating Detector Systems
5-45
Before setting the active element power, install a column and set the NPD flows as explained
later in this section.
1. Set the heated zones to the desired operating temperatures. Leave the oven at 50 °C.
Note: The temperature of the heated zone should be at least 200 °C.
2. Turn off the power to the detector and the active element by pressing:
WARNING
DO NOT LEAVE THE DETECTOR ON WHILE SETTING THE ACTIVE
ELEMENT POWER; IT MAY OVERHEAT AND BECOME PERMANENTLY
DAMAGED.
3. Set the active element power control to 000 by turning it fully counterclockwise.
Note: The locking lever immediately below the control knob is locked in the right-most
position and unlocked in the left-most position.
4. Before setting the active element power, enter the following:
1 SIG 1 1 (or f SIG2 1) displayed value
The displayed value on the Oven/Det status window is in pA and should be close to zero.
Allow approximately 1 minute for the baseline to stabilize.
5. Increase the element power slowly by turning the active element power control clockwise in
steps of 100 (waiting 1 minute in between steps) until the displayed signal value approaches
the target value. Expect little or no change at first, then a rapid increase as the element
becomes active.
Generally, the detector is adequately sensitive when enough power is supplied to the active
element to display a signal output value in the range of 20-30 pA.
Note: Operational power settings vary depending on the hydrogen and air flow rate, the
detector temperature, contamination, and the desired sensitivity. For the conditions in this
procedure, typical values range from 400—900. The power control can probably be increased
immediately to 300-400 while giving a negligible increase in offset on the detector. As
Operating Detector Systems
5-46
NPD
higher power settings are approached (500—600), increase the power more slowly and
carefully.
If you know the element power setting, bring power slowly to the setting and fine-tune if
necessary. Wait for the baseline to stabilize before setting a final value.
t
After reaching the proper range of offset, allow the detector to stabilize before expecting
precise measurements. The offset may drift until the active element becomes fully acclimated to the operating conditions. During this period, the apparent sensitivity of the
detector will change.
Setting the NPD Flow for Packed Columns
The gas flow rates outlined in this procedure ensure good, reliable detector behavior for the
majority of analyses. If it is necessary to modify the flow rates for a specific application, use a
standard sample matched to the application and experiment with the flow rates to optimize the
detector's behavior.
WARNING
TO MINIMIZE THE RISK OF EXPLOSION WHEN USING A BUBBLE
FLOW METER, NEVER MEASURE AIR AND HYDROGEN TOGETHER.
MEASURE THEM SEPARATELY.
This section assumes that the detector support gases are connected, the system is leak-free, the
correct jet is installed, and a column is installed.
1. Close the Aux gas on/off valve.
2. Attach a bubble flow meter to the NPD collector using the rubber adapter.
3. Set the column flow to approximately 20 ml/min.
4. Set the oven and the heated zones to the desired operating temperatures.
5. Set the column flow rate to 20 ml/min. Because the procedure for setting the column flow
rate depends on the type of column installed and inlet system used, refer to the information
about the appropriate inlet system in chapter 4, "Setting Inlet System Flow Rates."
NPD
Operating Detector Systems
5-47
6. Use the following steps to set the H2 flow rate to 3 to 4 ml/min:
a. Open the H2 on/off valve by turning it counterclockwise. Measure the total flow rate
(column plus makeup) through the detector.
b. Adjust the H2 pressure to the detector to obtain a total flow rate (H2 plus column) of 23
to 24 ml/min.
c. Turn the H2 off.
7. Use the following steps to set the air flow rate to 100 to 120 ml/min:
a. Open the air on/off valve by turning it counterclockwise. Measure the total flow
(column plus air) through the detector.
b. Adjust the air pressure to the detector to obtain a total flow of 120 to 140 ml/min.
c. Turn the air flow off.
8. Remove the flow measuring adapter and bubble flow meter from the NPD collector.
9. Open the H2 on/off valve.
Operating Detector Systems
5-48
NPD
Setting the NPD Flow for Capillary Columns
The following table and graph show the pressure and flow values for EPC of the NPD.
Typical Pressure versus Flow for FID Flow Reslriclors
Values computed using ambient temperature of 21 °C and pressure of 14.56 psi
FID Makeup
HP pn 19243-60540
Green and Red Dots
Flow Restrictor
FID Hydrogen
HP pn 19231-60660
Red Dot
Flow (ml/min)
Pressure
kPa
69.0
137.9
206.8
275.8
344.7
413.7
482.6
551.6
620.5
689.5
FID Air
HP pn 19234-60600
Brown Dot
psig
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
Nitrogen
Helium
Hydrogen
Air
6.4
15.0
26.0
39.0
53.0
69.0
86.0
104.0
123.0
143.0
7.2
17.0
29.0
44.0
61.0
80.0
100.0
122.0
150.0
178.0
2.0
4.6
8.1
12.4
17.0
22.3
21.0
45.0
76.0
110.0
148.0
188.0
229.0
273.0
318.0
363.0
= Recommended calibration points for using EPC with the HP 3365 ChemStation
NPD Restrictors
400
20
y
/Hyd ogen
300
/
/
200
o
100
if
20
NPD
H
40
60
Pressure (psig)
r
80
1
Air
15
• Helium
i Nitrogen
s
10 ET
cu
-a
5
100
=
120
Operating Detector Systems
5-49
WARNING
TO MINIMIZE THE RISK OF EXPLOSION WHEN USING A BUBBLE
FLOW METER, NEVER MEASURE AIR AND HYDROGEN TOGETHER.
MEASURE THEM SEPARATELY.
This section assumes that the detector support gases are connected, the system is leak-free, the
correct jet is installed, and a column is installed.
1. Set the oven and the heated zones to the desired operating temperatures.
2. Set the column flow rate to the desired value. Because the procedure for setting the column
flow rate depends on the type of column installed and inlet system used, refer to the
information about the appropriate inlet system in chapter 4.
3. Adjust the total carrier and makeup gas flow (column plus makeup) to at least 30 ml/min.
4. Attach a bubble flow meter to the NPD collector using the rubber flow measuring adapter.
5. Use the following steps to set the capillary makeup gas flow rate for either manual or
electronic pressure control.
Manual Pressure Control:
a. Set the supply pressure for the capillary makeup gas to about 276 kPa (40 psi).
b. Open the Aux gas on/off valve by turning it counterclockwise. Measure the total flow
rate (column plus makeup) through the detector.
c. Use a small screwdriver to turn the variable restrictor at the center of the on/off valve to
obtain a total flow rate of 30 ml/min (column plus makeup).
d. Use the following steps to set the H2 flow rate to 3 to 4 ml/min:
i. Open the H2 on/off valve by turning it counterclockwise. Measure the total flow rate
(column plus makeup plus H2) through the detector.
ii. Adjust the H2 pressure to the detector until the total flow reaches 33 to 34 ml/min.
iii. Turn the H2 flow off.
e. Use the following steps to set the air flow rate to 100 to 120 ml/min:
i. Open the air on/off valve by turning it counterclockwise. Measure the total flow rate
(column plus makeup plus air) through the detector.
ii. Adjust the air pressure to the detector until it reaches 100-120 ml/min.
Operating Detector Systems 5-50
NPD
Electronic Pressure Control:
a. Set the supply pressure to the auxiliary EPC channel to 40 psi.
b. Open the Aux gas (makeup gas) on/off valve. Turn the variable restrictor valve fully
counterclockwise. Then adjust the pressure to get the desired flow rate.
c. Select the pressure units you would like to use.
To change the units, press: [ sow H I 1 1 I ENTER 1. Then press the number of the
corresponding unit you want to use:
f~3~l = kPa
d. The example below sets the auxiliary channel C pressure to 10 psi.
Press:
E!SS&&B$ I
A
1 I
1
1 I ° 1 [ ENTER I
ACTUAL
SETPOINT
10.0
10.0
Sets auxiliary channel C pressure to 10 psi
The GC display looks like this
Note: To keep the pressure constant through an oven ramp program, see chapter 10,
"Using Electronic Pressure Control."
e. Adjust the makeup gas pressure to the detector as necessary to obtain 30 ml/min total
flow rate (column plus makeup).
6. Remove the bubble flow meter from the NPD collector.
7. Open the H2 on/off valve.
NPD
Operating Detector Systems
5-51
Turning the NPD On and Off
WARNING
DO NOT LEAVE THE DETECTOR ON WHILE SETTING THE ACTIVE
ELEMENT POWER; IT MAY OVERHEAT AND BE PERMANENTLY
DAMAGED.
To turn the NPD on, press:
(or
[~B~>
To turn the NPD off, press:
(or
[ B ))
)
After the oven and zones reach the desired setpoint values, wait an additional Vi-hour before
using the NPD.
Operating Detector Systems
5-52
NPD
Optimizing the Performance of the NPD
To optimize the performance of the NPD, you should avoid contamination of the detector and
preserve the lifetime of the active element (bead).
Avoiding Contamination
The slightest contamination can create serious NPD problems. The following list describes
common sources of contamination to avoid:
• Columns and/or glass wool treated with H3PO4 (phosphoric acid)
• Phosphate-containing detergents
• Cyano-substituted silicone column (such as XE-60 and OV-225)
• Nitrogen-containing liquid phases
• Any liquid phase deactivated for analysis of basic compounds
•
Fingerprints
• Leak-detection fluids
• Laboratory air
Contamination may affect the performance of an NPD in two ways:
• Positive contamination gives a more positive offset than what would normally result from a
clean system. In response to the positive offset, you may operate the detector with too little
power to the active element. Because the temperature of the active element is less than
normal, the detector appears less sensitive than is desirable.
• Negative contamination quenches the reaction, resulting in decreased sensitivity. Very high
contamination may completely quench all signals from the detector. If this happens, the
apex of a peak is flattened toward the baseline.
NPD
Operating Detector Systems
5-53
Preserving the Lifetime of the Active Element
The lifetime of the active element is reduced by silicon dioxide coating, loss of rubidium salt,
and humidity. Observe the following suggestions to preserve the lifetime of the active element:
• Prevent silicon dioxide from coating the active element. Residual silanizing reagents from
derivatization, and/or bleed from silicone columns, may coat the active element with silicon
dioxide. This decreases ionization efficiency, reducing sensitivity.
If silanizing is necessary, remove excess reagent before injection. Silicone columns should be
well conditioned and loaded less than 5%.
• Do not overheat the active element. Rubidium loss is caused by overheating the active
element, particularly if the element power is on when gas flows are interrupted (especially in
the carrier). You must turn off the detector or reduce the element power to zero when
changing the columns and/or replacing the gas cylinders. Power to the element while the gas
flow is off can destroy an element within a few minutes.
• Use the lowest element power possible, consistent with maintaining sufficient detector
sensitivity and selectivity for the particular analyses.
• Reduce the power to the active element whenever the detector will not be operated for
extended periods of time (such as over the weekend). To determine the proper amount of
power reduction, plot the normal offset and note the displayed zero value (20-30 is in the
normal range). Then reduce the power setting slightly until the displayed zero value (offset)
just goes to zero or to a value close to zero (lower than 5 picoamps). In this way, the
temperature of the active element will be lowered such that there will be little loss of
rubidium, but the active element will still be kept hot enough to prevent contamination
(condensation) while in standby.
• If you are using the auxiliary EPC channel to control the NPD gases, you can program
hydrogen to a lower value. This cools the bead and thereby extends the bead life.
• Counteract humidity. Humidity adversely affects the lifetime of an element. Keep the
detector warm (100 °C to 150 °C) when it is not in use. Store the collector (including spare
collectors) in a desiccator whenever you remove it from the NPD for an extended period of
time.
• Recoat or replace an old element. Invest in a recoating kit, which rejuvenates the active
element in an old collector. Also keep a spare collector available as a replacement.
Operating Detector Systems
5-54
NPD
• Generally, sensitivity and selectivity to nitrogen decreases as the element ages. Phosphorus
response is affected less than nitrogen response.
I
.•
• Do not remove the seals that cover the NPD during shipments until you are ready to
connect the column and operate the detector. Without the seals, the active element may
become contaminated, which will reduce the collector's effectiveness and possibly ruin the
active element.
Both the detector baseline and sensitivity change with the carrier flow rate due to changes in
the temperature of the active element. This causes baseline drift in pressure-controlled inlet
systems (capillary inlets) while temperature-programming the column. The amount of change in
the detector response is proportional to the ratio of the total column flow change (temperature
sensitive) to the makeup gas flow (not temperature sensitive); that is, total column flow change
divided by makeup gas flow. Adjust the element power after any change in the carrier flow rate.
When the detector is first turned on, its sensitivity and signal level change slowly over several
hours. Therefore, for applications requiring very stable operation, leave the detector on
overnight, lowering the oven temperature to prevent contaminating the active element with
column bleed.
NPD
Operating Detector Systems
5-55
Operating the Electron Capture Detector (ECD)
This section explains how to operate an electron capture detector (ECD). Specifically, it
describes the following:
• The basic operating characteristics of an ECD
• General issues to consider when using an ECD, including temperature, gases, flow rates,
and background
• Routine detector operating procedures, including setting the column flow, setting the carrier
gas selection switch, setting carrier gas and makeup gas flow rates, and performing daily
startup and shutdown procedures.
WARNING
THE GAS STREAM FROM THE DETECTOR MUST BE VENTED TO A
FUME HOOD TO PREVENT POSSIBLE CONTAMINATION OF THE
LABORATORY WITH RADIOACTIVE MATERIAL. FOR CLEANING
PROCEDURES, SEE "CLEANING THE DETECTOR" IN THIS CHAPTER.
Operating Detector Systems
5-56
ECD
Requirements for USA Owners
WARNING
DETECTOR VENTING MUST BE IN CONFORMANCE WITH THE LATEST
REVISION OF TITLE 10, CODE OF FEDERAL REGULATIONS, PART 20
(INCLUDING APPENDIX B).
THE DETECTOR IS SOLD UNDER GENERAL LICENSE: OWNERS MAY
NOT OPEN THE DETECTOR CELL OR USE SOLVENTS TO CLEAN IT.
ADDITIONAL INFORMATION IS AVAILABLE IN THE PUBLICATION
INFORMATION FOR GENERAL LICENSEES, PUB. NO. 43-5953-1586
(D).
OWNERS OF THIS DETECTOR MUST PERFORM A RADIOACTIVE LEAK
TEST (WIPE TEST) AT LEAST EVERY 6 MONTHS. SEE "TESTING FOR
RADIOACTIVE LEAKS (THE WIPE TEST)" IN THIS CHAPTER.
WARNING
IN THE EXTREMELY UNLIKELY EVENT THAT BOTH THE OVEN AND THE
ECD-HEATED ZONE SHOULD GO INTO THERMAL RUNAWAY
(MAXIMUM, UNCONTROLLED HEATING IN EXCESS OF 400 °C) AT THE
SAME TIME, AND THAT THE ECD REMAINS EXPOSED TO THIS
CONDITION FOR MORE THAN 12 HOURS, TAKE THE FOLLOWING
STEPS:
•
AFTER TURNING OFF THE MAIN POWER AND ALLOWING THE
INSTRUMENT TO COOL, CAP THE ECD INLET AND EXHAUST VENT
OPENINGS. WEAR DISPOSABLE PLASTIC GLOVES AND OBSERVE
NORMAL SAFETY PRECAUTIONS.
•
RETURN THE CELL FOR EXCHANGE FOLLOWING THE DIRECTIONS
INCLUDED WITH THE FORM GENERAL LICENSE CERTIFICATION
(HP PUB. NO. 43-5954-7621, HP PART NUMBER 19233-90750).
EVEN IN THIS VERY UNUSUAL SITUATION, RADIOACTIVE MATERIAL IS
UNLIKELY TO ESCAPE THE CELL. PERMANENT DAMAGE TO THE 63 NI
PLATING WITHIN THE CELL IS POSSIBLE, HOWEVER, SO THE CELL
MUST BE RETURNED FOR EXCHANGE.
ECD
Operating Detector Systems
5-57
Introduction
The electron capture detector (ECD) cell contains 63Ni, a radioactive isotope emitting
high-energy electrons ((3-particles). These undergo repeated collisions with carrier gas
molecules, producing about 100 secondary electrons for each initial p-particle.
Further collisions reduce the energy of these electrons into the thermal range. These
low-energy electrons are then captured by suitable sample molecules, thus reducing the total
electron population within the cell.
Uncaptured electrons are collected periodically by applying short-term voltage pulses to the cell
electrodes. This cell current is measured and compared to a reference current. The pulse
interval is then adjusted to maintain constant cell current.
Therefore pulse rate (frequency) rises when an electron-capturing compound passes
through the cell. The pulse rate is converted to a voltage, which is related to the amount of
electron-capturing material in the cell.
The ECD responds to compounds having an affinity for electrons—for example, halogenated
materials such as pesticides and related compounds. The following table shows expected
sensitivities to different classes of organic compounds.
Operating Detector Systems
5-58
ECD
General Considerations
General ECD Sensitivity to Various Classes of Compounds
Chemical Type
Relative Sensitivity
Hydrocarbons
1
Ethers, esters
10
Aliphatic alcohols, ketones, amines;
mono-CI, mono-F compounds
102
Mono-Br, di-CI and di-F compounds
103
Anhydrides and tri-CI compounds
104
Mono-I, di-Br and nitro compounds
105
Di-I, tri-Br, poly-CI and poly-F compounds
106
The figures in the table are only approximate, and sensitivity varies widely within each group,
depending on the structure of the material. For example, DDT with 5 chlorine atoms per
molecule can be measured in the 1- to 10-picogram range.
Temperature Effects
Some compounds exhibit strong response to detector temperature. The effect may be either
positive or negative. Try different detector temperatures above the oven temperature to
determine the effect on sensitivity. Generally, a detector temperature between 250 and 300 °C
is satisfactory for most applications.
Gases
The ECD is designed for use with either nitrogen or argon-methane as carrier gas. Nitrogen
yields somewhat higher sensitivity with approximately the same minimum detectable limit, but
is also accompanied by higher noise and occasional negative solvent peaks. Argon-methane
gives a greater dynamic range. Use the appropriate switch to select carrier gas type. The ECD
does not operate properly if the switch is set incorrectly.
Because of its high sensitivity, never use the ECD without moisture, chemical, and O2 traps in
carrier and makeup lines. The traps should be in good condition and installed in the carrier gas
supply line and the makeup gas supply. Also, avoid using plastic tubing, which is permeable to
most gases, for all connections. Use clean copper tubing instead.
ECD
Operating Detector Systems
5-59
Columns and Flow Rates
An ECD is normally used to detect compounds that are reactive enough to interact with metal
columns. Therefore, only 1/4-inch packed glass or fused silica capillary columns are recommended with this detector.
Hydrogen carrier gas (with nitrogen makeup gas) gives the best column performance.
Argon-methane can also be used as makeup gas. For most purposes, 50-60 ml/min of makeup
gas is satisfactory, but the rate may be increased to 100 ml/min for very fast runs. Because the
ECD is a concentration-dependent detector, increasing the flow rate reduces sensitivity but can
extend the linear range.
Note: When measuring ECD flow rates, attach a bubble flow meter directly to the detector
exhaust vent using a small piece of rubber tubing as an adapter.
Background
If the ECD becomes contaminated from impurities in the carrier (or makeup) gas or from
column bleed, a significant fraction of detector dynamic range may be lost. In addition, the
output signal becomes noisy.
To check the background level, allow ample time for the components from the previous
analyses to be flushed from the system and then make a blank run (one with no sample
injected).
Setting Up the ECD for Operation
To set up the ECD for operation, you must:
• Set the carrier gas selection switch (if it is not done already)
• Set the ECD flow (for either packed or capillary columns)
Operating Detector Systems
5-60
ECD
Setting the Carrier/Makeup Gas Selection Switch
The carrier gas selection switch is located on the detector board behind the right instrument
side panel. Use the following procedure to set the carrier gas selection switch if necessary:
1. Turn off the power and unplug the instrument.
2. Remove the top right cover by lifting first at its rear edge and then sliding it toward the rear
of the instrument.
3. Remove the right side panel by removing four screws, two along its bottom edge and two
along its top edge.
4. Locate the ECD signal board, which is next to the detector.
5. Locate the N2-Ar/CH4 switch and place it in the appropriate position based on the type of
predominant gas at the detector (carrier or makeup).
6. Replace the panels.
ECD Carrier Gas Selector Switch
ECD Carrier
Gas Selector
Switch
Up: N 2
Down: Ar/CH4
ECD
Operating Detector Systems
5-61
Setting the ECD Flow for Packed Columns
Gas flow rates given in this section ensure good, reliable detector behavior for most
applications. To optimize detector behavior for a specific application, use a standard sample
matched to the application and experiment with other flow rates.
Use the steps in the following procedure to set the ECD flow in the column. This procedure
assumes that the detector support gases are connected, the system is leak-free, and a column is
installed. If your system has electronic pressure control, enter the flows at the keyboard using
the instructions on the following page under "Electronic Pressure Control."
1. Set the column flow to the desired rate. Because the procedure for setting the column flow
rate depends on the column installed and the inlet system in use, refer to the appropriate
system information in chapter 4.
2. Open the ECD Anode Purge On/Off valve. Supply pressure of 30 psi will deliver approximately 3 ml/min of purge flow. ECD anode purge flow is not considered part of total
column flow.
Packed Column Considerations: Either N2 or Ar containing 5% CH4 may be used as carrier
gas. N2 yields somewhat higher sensitivity, but it is accompanied by higher noise; minimum
detectable limit is about the same. N2 sometimes produces a negative solvent peak. Ar/CH4
gives greater dynamic range.
Total flow of 60 ml/min is adequate in most applications to prevent peak broadening and
maximize linearity.
The carrier gas must be dry and O2-free. Moisture and O2 traps are strongly recommended for
highest sensitivity. Because plastic tubing is permeable to many gases, the use of clean copper
tubing is recommended for all connections.
Operating Detector Systems
5-62
ECD
Setting the ECD Flow for Capillary Columns
The following table and graph show the optimal pressure and flow values for EPC or the ECD.
Typical Pressure versus Flow for ECD Flow Restriclors
Values computed using ambient
temperature of 21 °C and pressure of 14.56 psi
Flow Restrictor
ECD Makeup
HP pn 19231-60770
Red Dots
Pressure
Flow (ml/min)
kPa
psig
69.0
137.9
206.8
275.8
344.7
413.7
482.6
551.6
620.5
689.5
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
Nitrogen
8.0
20.0
34.0
51.0
69.0
89.0
110.0
132.0
156.0
181.0
Argon-Methane
7.0
17.0
29.0
44.0
60.0
78.0
97.0
117.0
138.0
160.0
= Recommended calibration
points for using EPC with the
HP 3365 ChemStation
Note: The anode purge flow rates will be approximately 1/lOth of the values shown above at the
same pressure settings.
ECD Restrictors
200
(ml/min)
/
o
u_
• Nitrogen
i Argon-Methane
-ten
y
100
s
r
50
• ^
0
D
ECD
20
40
60
Pressure (psig)
80
100
120
Operating Detector Systems
5-63
To optimize detector behavior for a specific application, use a standard sample matched to the
application and experiment with other flow rates.
Use the steps in the following procedure to set the ECD flow in the column.
1. Set the column flow to the desired rate. Because the procedure for setting column flow rate
depends on the column installed and the inlet system used, refer to the appropriate system
information in chapter 4.
Supply pressure for the makeup gas and anode purge should be set to 207 kPa (30 psi).
2. Open (counterclockwise) the On/Off valve for ECD makeup gas flow. Supply pressure of
60 psi will deliver approximately 60 ml/min of makeup gas flow.
3. Open the ECD Anode Purge On/Off valve. Supply pressure of 60 psi will deliver
approximately 6 ml/min of purge flow. ECD anode purge flow is considered part of total
column flow.
Capillary Column Considerations: H2 or He carrier gas affords the best column performance
with reduced retention times. Ar/CH4 or N2 as makeup gas is used in the range of 60 ml/min.
Because the ECD is a concentration-dependent detector, reduced sensitivity is obtained at
higher flow rates.
For the ECD, capillary makeup gas should be used even with HP Series 530 \x capillary columns
because the detector requires a total flow rate of at least 25 ml/min.
Moisture and O2 traps for carrier and makeup gas are essential with capillary/ECD operation.
Your ECD makeup gas is equipped with either manual or electronic pressure control. Set
the makeup gas according to the instructions for your instrument.
Manual Pressure Control:
a. Set the supply pressure for the capillary makeup gas to about 276 kPa (40 psi).
b. Open the on/off valve for the ECD makeup gas flow by turning it counterclockwise.
c. Use a small screwdriver to turn the variable restrictor at the center of the on/off valve as
necessary to obtain a flow of 60 ml/min.
Operating Detector Systems
5-64
ECD
Electronic Pressure Control:
a. Set the supply pressure to the auxiliary EPC channel to 40 psi.
b. Open the Aux gas (makeup gas) on/off valve. You will use the auxiliary EPC pressure to
control the auxiliary gas flow rate.
s^^7
c. Select the pressure units you would like to use.
To change the units, press: jjipaifl I i I I ENTER 1. Then press the number of the
corresponding unit you want to use:
d. With electronic pressure control, makeup gas is controlled through auxiliary pressure
channels C, D, E, or F from the keyboard. The example below sets the auxiliary channel
C pressure to 40 psi.
[
$gpf> C
40.0
Sets auxiliary channel C pressure to 10 psi
40.0
The GC display looks like this
Note: To keep the pressure constant through an oven ramp program, see chapter 10,
"Using Electronic Pressure Control."
e. Adjust the makeup gas pressure to the detector as necessary to obtain an appropriate
total flow rate (column plus makeup).
For the ECD, use capillary makeup gas even with HP Series 530 fx capillary columns because
the large cell size requires high total flow rate (at least 50—60 ml/min).
For an ECD, the makeup gas is added into the column effluent stream via a capillary makeup
gas adapter fitted into the detector column inlet.
ECD
Operating Detector Systems
5-65
Testing for Contamination
Because of its very high sensitivity, the ECD is particularly prone to contamination problems,
including contaminants entering the system via the carrier and makeup gas source.
Perform the following procedure whenever a new carrier gas source is installed:
1. With the instrument on and operating normally, cool the oven to ambient temperature, turn
off the detector, turn off carrier flow to the detector, and remove the column to the ECD. If
a capillary column was installed, also remove the makeup gas adapter in the detector base.
2. Disconnect the carrier gas source line at its fitting on the rear of the inlet used.
Note: If your carrier gas is helium or hydrogen (not N2 or Ar-CH4), then use the makeup
gas, not the carrier gas.
3. Using a Vespel ferrule, and adapters as necessary, connect the carrier source line to the
detector base, including any traps in the line.
4. Set the carrier pressure to about 7 kPa (1 psi) and check for flow through the detector.
5. Leaving the oven door open, enter any temperature for the detector up to 250 °C.
6. Turn on the detector electronics.
7. Assign the ECD to one of the monitored signals.
8. Within 15 minutes, the displayed signal values on the Oven\Det Status window should be
between 40 to 100 (400 to 1,000 Hz); there may be downward drift.
9. If the displayed values are greater than 1,000 Hz, the trap(s) may be at fault. Connect the
carrier gas supply line directly to the detector base and repeat the test. If the values are still
out of range, then the carrier gas supply or the detector may be contaminated. Try a new
tank of N2 or Ar-CH4. If the system is fine, then the gas was contaminated. If not, the cell is
probably dirty and should be exchanged.
Operating Detector Systems
5-66
ECD
Testing for Leaks
Note: This test assumes that the flow system components upstream from the detector are
leak-free.
Use the steps in the following procedure to test for leaks at the ECD:
1. Set the inlet, oven, and detector to ambient temperature and allow time for cooling. Turn
off the detector and carrier flow.
2. Use a vent plug to cap the ECD exhaust vent.
3. Set the carrier gas pressure to an appropriate valve depending on the inlet system you are
using. Open the carrier gas mass flow controller fully to ensure that flow through the system
is available. Allow time for the system to become fully pressurized.
4. Close the carrier gas flow at its source and monitor system pressure.
5. If no pressure drop is observed over a 10-minute period, assume that the system is leak-free.
6. If leakage is observed, use an appropriate electronic leak detector to check for leaks at the
detector column fittings and at the plugged vent.
Note: The detector body itself is not a likely source of leaks. It cannot be disassembled
without special license from the Nuclear Regulatory Commission or Agreement State
Licensing Agency (USA only).
Testing for Radioactive Leaks (the Wipe Test)
ECDs must be tested for radioactive leaks at least every 6 months. Records of tests and results
must be maintained for possible inspection by the Nuclear Regulatory Commission and/or
responsible state agency. More frequent tests may be conducted when necessary.
A wipe test kit, supplied with each new ECD, contains complete instructions for conducting the
test.
ECD
Operating Detector Systems
5-67
Operating the Flame Photometric Detector (FPD)
Flow Panel for Controlling FPD Operation
Ignitor Button
(press to ignite)
On/Off Valve,
Air
On/Off Valve,
Capillary Makeup
Gas
On/Off Valve,
H2 (Hydrogen)
Setting Up the FPD for Operation
To set up the FPD for operation, you must:
• Set the FPD flow (for either packed or capillary columns)
• Set the FPD sensitivity
• Turn on the FPD
Operating detector Systems
5-68
FPD
Setting the FPD Flow for Packed Columns
The gas flow rates given in this section ensure good, reliable detector behavior for most
applications. To optimize detector behavior for a specific application, use a standard sample
matched to the application and experiment with other flow rates.
WARNING
FLAME PHOTOMETRIC DETECTORS USE HYDROGEN GAS AS FUEL.
IF HYDROGEN FLOW IS ON AND NO COLUMN IS CONNECTED TO THE
DETECTOR INLET FITTING, HYDROGEN GAS CAN FLOW INTO THE
OVEN AND CREATE AN EXPLOSION HAZARD. INLET FITTINGS MUST
HAVE EITHER A COLUMN OR A CAP CONNECTED WHENEVER
HYDROGEN IS SUPPLIED TO THE INSTRUMENT.
Use the steps in the following procedure to set the FPD flow in a packed column. This
procedure assumes that detector support gases are connected, the system is leak-free, and a
column is installed.
1. Close the Aux gas on/off valve.
2. Set the column flow rate to 20 ml/min. Because the procedure for setting column flow rate
depends on the column installed and the inlet system used, refer to the appropriate inlet
system information in chapter 4.
3. Set the oven and heated zones to the desired operating temperatures.
4. Attach a bubble flow meter to the FPD vent tube.
WARNING
TO MINIMIZE RISK OF EXPLOSION WHEN USING A BUBBLE FLOW
METER, NEVER MEASURE AIR AND HYDROGEN TOGETHER.
MEASURE THEM SEPARATELY.
To optimize sulfur sensitivity, use a lower hydrogen flow rate (50—60 ml/min is recommended). To optimize phosphorus sensitivity, use a higher hydrogen flow rate (about 100
ml/min is recommended).
FPD
Operating Detector Systems
5-69
5. Use the following steps to set the H2 flow rate to 75 ml/min:
a. Open the H2 on/off valve by turning it counterclockwise. Measure the total flow rate
(column plus H2) through the detector.
b. Adjust the H2 pressure to the detector to obtain a total flow rate (column plus H2) of
about 95 ml/min.
c. Close the H2 on/off valve.
6. Use the following steps to set the air flow rate to 100 ml/min.
a. Open the air on/off valve by turning it counterclockwise and measure the total flow rate
(column plus air) through the detector.
b. Adjust the air pressure to the detector to obtain a total flow rate (column plus air) to
120 ml/min.
7. Remove the measuring adapter from the FPD collector.
8. Open the H2 on/off valve. To ignite the flame, see "Igniting the FPD Flame" later in this
chapter.
Operating detector Systems
5-70
FPD
Setting the FPD Flow for Capillary Columns
This table and graph show the optimal flow rates at which to control your FPD with EPC.
Typical Pressure versus Flow for FPD Flow Restrictors
Values computed using ambient temperature of 21 °C and pressure of 14.56 psi
FPD Makeup
HP pn 19243-60540
Green and Red Dots
Flow Restrictor
FPD Hydrogen
HP pn 19234-60570
Red Dot
Pressure
kPa
69.0
137.9
206.8
275.8
344.7
413.7
482.6
551.6
620.5
689.5
FPD Air
HP pn 19234-60570
Brown Dot
Flow (ml/min)
psig
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
Nitrogen
Helium
Hydrogen
6.4
15.0
26.0
7.2
17.0
29.0
44.0
61.0
80.0
100.0
31.0
73.0
126.0
189.0
259.0
336.0
39.0
53.0
69.0
86.0
104.0
123.0
143.0
Air
15.0
34.0
57.0
84.0
113.0
143.0
178.0
122.0
150.0
178.0
212.0
248.0
284.0
= Recommended calibration points for using EPC with the HP 3365 ChemStation
FPD Restrictors
300
1
/Hyd
ogen
250
/
/
200
> Helium
, Nitrogen
5
1100
/
/
20
FPD
/
/
150
50
Air
40
60
Pressure (psig)
80
100
120
Operating Detector Systems
5-71
The gas flow rates given in this section ensure good, reliable detector behavior for most
applications. To optimize detector behavior for a specific application, use a standard sample
matched to the application and experiment with other flow rates.
WARNING
FLAME PHOTOMETRIC DETECTORS USE HYDROGEN GAS AS FUEL.
IF HYDROGEN FLOW IS ON AND NO COLUMN IS CONNECTED TO THE
DETECTOR INLET FITTING, HYDROGEN GAS CAN FLOW INTO THE
OVEN AND CREATE AN EXPLOSION HAZARD. INLET FITTINGS MUST
HAVE EITHER A COLUMN OR A CAP CONNECTED WHENEVER
HYDROGEN IS SUPPLIED TO THE INSTRUMENT.
Use the steps in the following procedure to set the FPD flow in a capillary column. This
procedure assumes that the detector support gases are connected, the system is leak-free, and a
column is installed.
1. Set the oven and the heated zones to the desired operating temperatures.
2. Set the column flow to the desired rate. Because the procedure for setting column flow rate
depends on the column installed and the inlet system used, refer to the appropriate inlet
system information in chapter 4.
3. Set the carrier and makeup gas flow rate (column plus makeup) through the detector to at
least 20 ml/min.
4. Attach a bubble flow meter to the FPD vent tube.
Your FPD makeup gas is equipped with either manual or electronic pressure control. Set
the makeup gas according to the instructions below. To set capillary makeup gas flow rate:
Manual Pressure Control:
a. Set the supply pressure for the capillary makeup gas to about 276 kPa (40 psi).
b. Open the Aux gas on/off valve for the FPD makeup gas flow by turning it
counterclockwise.
c. Use a small screwdriver to turn the variable restrictor at the center of the Aux gas on/off
valve as necessary to obtain 20 ml/min total flow rate (column plus makeup).
Operating detector Systems
5-72
FPD
Electronic Pressure Control:
a. Set the supply pressure to the auxiliary EPC channel to 60—70 psi using the keyboard.
b. Open the Aux gas (makeup gas) on/off valve. Use the auxiliary EPC pressure to control
the auxiliary gas flow rate.
c. Select the pressure units you would like to use.
To change the units, press: P&siii 1 i I 1 ENTER I . Then press the number of the
corresponding unit you want to use:
d. The example below sets the auxiliary channel C pressure to 10 psi.
1 | I o I [ ENTER 1
EPP C
v^•
ACTUAL
SETPOINT
10.0
10.0
sets auxiliary channel C pressure to 10 psi
The GC display looks like this
Note: To keep the pressure constant through an oven ramp program, see chapter 10,
"Using Electronic Pressure Control."
e. Adjust the makeup gas pressure to the detector as necessary to obtain 20 ml/min total
flow rate (column plus makeup).
WARNING
TO MINIMIZE RISK OF EXPLOSION WHEN USING A BUBBLE FLOW
METER, NEVER MEASURE AIR AND HYDROGEN TOGETHER.
MEASURE THEM SEPARATELY.
5. Set the H2 flow rate to 75 ml/min. If you have a manually controlled system, use the steps
below. If you have EPC, enter the flow rate from the keyboard as you did for makeup gas.
i
a. Open the H2 on/off valve by turning it counterclockwise. Measure the total flow rate
(column plus makeup plus detector) through the detector.
b. Adjust the H2 pressure to the detector to obtain a total flow rate (column plus makeup
plus H2) of about 95 ml/min.
c. Close the H2 on/off valve.
FPD
Operating Detector Systems
5-73
6. Use the following steps to set the air flow rate to 100 ml/min:
a. Open the air on/off valve by turning it counterclockwise and measure the total flow rate
(column plus makeup plus air) through the detector.
b. Adjust the air pressure to the detector to obtain a total flow rate (column plus makeup
plus air) to 120 ml/min.
7. Remove the flow measuring adapter from the FPD collector.
8. Open the H2 on/off valve.
Turning the FPD On and Off
After setting the flows, you can turn the FPD on or off.
To turn the FPD on, press: [PETJ I A ) ( o r | B n
I ON 1.
To turn the FPD off, press: ("EH I~~A~I (or G O ) C°EQ •
Igniting the FPD Flame
WARNING
TO MINIMIZE THE RISK OF EXPLOSION, DO NOT ATTEMPT TO IGNITE
THE FPD FLAME BY APPLYING A FLAME AT ITS EXHAUST TUBE.
FOLLOW THE PROCEDURE BELOW.
Note: After the flows are set, the FPD flame is relatively easy to ignite. The detector module is
most easily lit if heated to at least 200 °C. Use the sequence described below to avoid a loud
pop on ignition.
1. Turn all FPD flows (except the column flow) off.
2. If required, open the auxiliary N2 valve.
3. Open the air (or O2) valve.
4. Press in and hold the igniter button.
5. Open the H2 valve.
Note: Always open the hydrogen valve after opening the air (or O2) and pressing the igniter.
Failure to do this will result in a loud pop. This should not damage the detector, but is
unpleasant to hear.
Operating detector Systems
5-74
FPD
6. Release the igniter button.
Proper ignition should result in a slightly audible pop. Flame ignition can be verified by
holding a mirror or a cold, shiny surface near the exhaust tube and observing condensation.
Ignition also usually results in a small increase in signal offset on the LED display.
FPD
Operating Detector Systems
5-75
Contents
Chapter 6:
Controlling Signal Output
Assigning a Signal
Displaying or Monitoring a Signal
Zeroing Signal Output
Turning Zero Off/On
Setting Signal Attenuation
Turning Attenuation Off/On
Inverting TCD Signal Polarity
Using Instrument Network (INET)
6-2
6-5
6-7
6-8
6-9
6-12
6-12
6-14
6
Controlling Signal Output
Signal Definition
and Control
V - - - - - - - - '
Output sources include detector signal(s), heated zone or oven temperatures, carrier gas flow
rates, column compensation run data, or test chromatographic data. If both signal channels are
present, each may output information simultaneously from the same source, or from two
different sources.
Each channel provides two levels of analog output:
0 to +1 mV:
for strip chart recorders.
-0.01 to +1 V:
for electronic integrators with analog inputs.
The two output levels are independent and may be connected simultaneously to separate
data-receiving devices.
Note: A tick mark (electrical pulse) is produced at the +1 mV analog output when either
[ START 1 or [ STOP 1 is pressed and when a run times out (run time elapses). These marks
locate beginning and ending points in a chromatogram plotted at a continuously running strip
chart recorder.
Controlling Signal Output
6-1
Assigning a Signal
After the appropriate signal channel is displayed by pressing 1 SIB 1 I (Or 1 SIG2 1, if
Option 550/Accessory 19242A or Option 560/Accessory 19254A is installed), any one of the
instrument functions in the following table may be entered to assign the signal to be output
from the displayed channel.
Note that in a two-channel instrument it is permissible to have the same signal assigned to each
signal channel, allowing identical data to be treated differently simultaneously.
Controlling Signal Output 6-2
Key(s)
Notes
To output the signal from either detector A or detector B
A
or
The message DET A (or B) NOT INSTALLED is displayed if
detector A (or B) is not present.
B ]
w
To output a difference signal between two detectors of the same
type
or
The message DET A (or B) NOT INSTALLED is displayed
if detector A (or B) is not present; the message UNLIKE
DETECTORS is displayed if detectors A and B are not of
the same type.
.JLJ
L_J I
COL COMP f
j
j o output a difference signal between a given detector and column
and a stored blank run signal for the detector and column
or
B
|
1 -
|
[
COL COMP 1
1
A j
| -
| [ COLCOMP2
1
or
or
m
[ coLcoMP2
The message DET A (or B) NOT INSTALLED is displayed if
detector A (or B) is not present.
To output oven temperature
or
or
or
To output stored COMP 1 or COMP 2 data
To output, respectively, inlet A temperature, inlet B temperature,
detector A temperature, or detector B temperature
To output, respectively, carrier gas flow rate A or B
To output a test signal (stored chromatogram) for use in verifying
proper operation of a data-receiving device (integrator, chart
recorder, etc); details are discussed later in this section.
w
Controlling Signal Output
6-3
As an example, a key sequence to assign detector B data to the Signal 1 output channel would
be:
SIQ 1 1
B I I ENTER
At the same time, A flow rate data (if electronic sensing is installed) could be assigned to the
Signal 2 output channel:
SIQ 2
1
7 1 I ENTER
As an assignment is made for each channel, confirmation is given through appropriate displays.
Controlling Signal Output 6-4
Displaying or Monitoring a Signal
By pressing the appropriate signal key (1 SIG1
ing signal channel is displayed.
or t siG2
^ current status of the correspond-
Two types of displays are possible: either a display showing the instrument function assigned to
the particular signal channel or a display monitoring the current actual output value for the
assigned instrument function. Repeatedly pressing t SIG1 1 (or 1 SIG2 1) switches between the
two possible display types.
Controlling Signal Output
6-5
Typical Signal Displays:
Detector Signal Assignments:
ACTUAL
SETPOINT
ACTUAL
SETPOINT
ACTUAL
SETPOINT
SIGNAL 1 A
Detector Signal Monitoring:
Oven/Zone Temperature Assignment:
SIGNAL 1
Oven/Zone Temperature Monitoring:
OVEN
SETPOINT
ACTUAL
15998
SIGNAL 1
Flow Rate Assignments:
TZMP
ACTUAL
SETPOINT
liiSJGlAlliillliiililtl iiiiiitiii
Flow Rate Monitoring:
ACTUAL
SIGNAL 1
SETPOINT
30.2
Signal monitoring is useful, for example, in determining if an FID is ignited, in setting active
element current for an NPD, in determining cleanliness of an ECD, in tracking temperatures or
gas flow rates, etc. The monitored value displayed is unaffected by scaling functions performed
by [ ZERO \ > [ RANGE 2 (f"1 ; and/or [ATTN2TO "~> (these key functions are discussed later).
If oven or heated zone temperature is monitored via the display, the conversion factor between
the displayed value versus actual temperature is 64 counts/ 0 C —200. Similarly, if flow rate is
monitored via the display, the conversion factor is 32 counts/(ml/min).
Controlling Signal Output 6-6
Zeroing Signal Output
V
When using analog signal output, using I ZER0 1 can increase dynamic range available by
subtracting a constant background signal from the detector signal. Background signal sources
include the detector itself (background level depending upon detector type), column bleed, or
contaminants in supply gas(es). There are limits to this, however, so it is good practice to
reduce background as much as possible by minimizing column bleed by using clean supply gases
and by performing proper detector maintenance.
Current I ZER0 1 setpoint value is displayed by pressing the appropriate signal channel key
(1 SIG1 1 or 1 SIG2 1), followed by I ZER0 1 (or simply press 1ZERO 1 alone, if the desired signal
channel is already displayed). Typical displays are shown below.
Typical Zero Displays
ACTUAL
SETPOINT
iiliiil
ACTUAL
SIG 2 NOT
INSTALLED
ACTUAL
ZERO 1
194,8
ACTUAL
ZERO
LIMIT
SETPOINT
SETPOINT
orrf
SETPOINT
$30000
Once current I ZERO 1 setpoint value is displayed for the desired signal channel, pressing
causes the value to be changed to the current signal value.
Zeroing should be done only at times of quiet chromatographic activity (i.e., not during a run).
To do so during an active run may cause a baseline shift at the recording/integrating device.
If the t ZER0 1 setpoint value determination is not appropriate for a particular application, any
value from -830000.0 through 830000.0 may be entered at the keyboard.
Entering a value LESS than the current QEROD value shifts background baseline UPWARD
(but at the expense of available output range); for example, to capture negative peaks or to
compensate for negative baseline drift.
Controlling Signal Output
6-7
Turning Zero Off/On
When the current setpoint offset value for 1 ZER° 1 is displayed for the desired output channel,
pressing I°FF 1 halts subtracting the offset value from the signal. Baseline is restored to its
absolute level with respect to the HP 5890 electrical zero.
•
The current setpoint value remains stored; however, pressing I 0N I resumes subtracting
the offset value from the signal.
•
If t ZERO 1 is off, pressing I ENTER 1 switches the zeroing function on and causes a I ZER0 1
determination.
Controlling Signal Output 6-8
Setting Signal Attenuation
For analytical information from a detector, f RANGE 2T0 1 and f ATTN2T0 1 are used to keep
peaks of interest on scale at the integrator or chart recorder. Peaks of interest must neither flat
top by exceeding the allowed maximum output level nor be too small to be measured.
[ RANGE 2T0 1 selects and sizes a portion of the full dynamic range for the signal source assigned
to an output channel. The portion selected is sized such that the highest possible value for the
portion does not exceed maximum output voltage allowed for the given output ( + 1 mV or
+ 1 V).
[ ATTN2T0 1 further selects and sizes a portion of the ranged signal for the +1 mV output to
ensure that the signal does not exceed +1 mV.
Note: [ATTN2TO 1 functions only for the strip chart recorder output (+1 mV) and acts on the
signal AFTER it has been ranged by t RANGE 2T0 1 .
For strip chart recorders (analog signal output + 1 mV): is attenuated via L RANGE 2T0 1 and
[ ATTN2T0 1 . For [ ATTN2T0 1, each step to a higher value reduces the output signal level
(as defined by [ RANGE 2T0 1 ) by half.
Signal
+ 1 mV Output Level =
[ RANGE 2T()
1
[ ATTN2tn
2
1
2
For electronic integrators (analog signal output +1 V): is attenuated via [RANGE 2T0 1 from the
HP 5890 and must be set at the integrator. Each step to a higher setpoint value decreases the
output signal level by a factor of 2 (half the previous level).
Signal
+ 1 V Output Level =
^""'*"
[ RANGE 2T()
I
As an example, a key sequence set attenuation and/or range would be:
or I
SIG2
1 CRANGE2T0 J
SIGI I or I siG2 1 [ATTN2T0
<value>
1 <value>
I ENTER
I ENTER!
Controlling Signal Output
6-9
The table below gives values permitted for either function, and the output affected.
Valid Setpoints For
Permitted
Setpoints
Key
( RANGE 2"T()
1
' ATTN 2 T ( ) ~ ~ l
t RANGE ato
1 And
£ ATTN2TO
1
Affected Output
Oto 13
B0TH+1mV&+1 V
0to10
0NLY+1mV
Generally, if both an integrator or A/D converter ( + 1 V output) and chart recorder
( + 1 mV output) are connected to the same signal channel, f RANGE 2T0 1 should be set properly
first for the integrator or computer, then [ ATTN2T0 1 set appropriately for the chart recorder.
To minimize integration error for an integrator or A/D converter, [RANGE at ( ) 1 should normally
be set to the lowest value possible, provided the largest peaks of interest do not exceed 1 volt.
Attenuation functions at the integrating device or computer are then used to ensure that
plotted peaks remain on scale.
Controlling Signal Output 6-10
The table below lists maximum detector output producing +1 volt at the +1V output for each
RANGE 2 T 0
1 setpoint value.
Maximum Detector Signal
1
•
Producing + 1 V Output
1
[ RANGE 2T()
|
FID & NPD (pA)
TCD (mV,
High Gain)
1
TCD (mV,
Low Gain)
ECD (kHz)
0
1.0x103
25
800
10
1
2.0 x10 3
50
D
20
2
4.0 x10
3
D
D
40
8.0 x10
3
D
D
80
4
D
D
160
4
D
D
320
6
6.4 x10
4
D
D
D
7
1.3x105
D
D
D
8
2.6 x10 5
D
D
D
9
5.1 x105
D
D
D
10
1.0x106
D
D
D
11
2.0 x106
D
D
D
12
4.1x106
D
D
D
13
8.2 x10 6
D
D
D
3
4
5
1.6x10
3.2X10
From the table above, note that for a TCD, [ RANGE 2T0 1 = 0 is suitable for virtually all
applications because the entire linear output range of the detector is included. Likewise,
[ RANGE 2T0 1 settings from 0 through 5 cover the entire useful output range for an ECD. Only
an FID or NPD may require use of the higher r RANGE 2T0 1 settings.
Controlling Signal Output
6-11
Turning Attenuation Off/On
The +1 mV strip chart recorder signal output can be switched off, providing no signal to the
data-receiving device. This is often useful in setting the zero position at a connected strip chart
recorder.
This is done through the following key sequence:
1 SIG 1 1 o
r
[ SIG 2 1
[ATTN2T0
1 [OFF]
After setting the pen to the desired zero position at the connected chart recorder, the current
attenuation value is restored by pressing I °N I.
Entering a new [ ATTN2T0 1 value overrides OFF.
Inverting TCD Signal Polarity
Note: Expect a baseline shift any time signal polarity is inverted. This may require a baseline
reset at a connected integrator or chart recorder.
TCD output is ONE signal representing thermal conductivity difference between two flows
(column effluent and reference gas).
• Enter the key sequence:
to assign the signal to an output channel (either A or B).
• For components giving NEGATIVE-going peaks,
fDETl [~A~|
( o r f~B~j )
(~n
inverts detector output polarity.
Repeating the entry (or simply pressing I - 1 again if the TCD is still displayed) inverts polarity
again to its original state.
Controlling Signal Output 6-12
Where a given sample has components giving both positive- and negative-going peaks, a
timetable command can be used to invert detector polarity during a run.
For example, to create a timetable event to invert TCD polarity at 1 minute into a run, enter
the key sequence:
either detector
l~T~j or I B I
\
|DETl | A 1
| -
|
[ TIME 1
[ 1 I
("IT
Repeating the entry later in the run inverts polarity again to its original state.
Polarity returns to its original state automatically at the end of the run.
Controlling Signal Output
6-13
Using Instrument Network (INET)
The "Instrument Network" (INET) is a path for various devices to communicate with each
other (data and/or commands). INET permits a group of devices (consisting of a "controller"
and some number of data "Producers" and data "Consumers") to function as a single, unified
system.
In using the INET function, chromatographic parameters are entered normally through the
HP 5890 keyboard. Integration parameters are entered at the controller. Parameters for other
devices on the INET loop may be entered at the controller or at their own keyboards.
Collectively, the separate sets of parameters constitute a single set of parameters for an
"analysis."
In DEFAULT operation, the HP 5890 supplies ONLY "Signal 1" data to the INET loop. That
is, HP 5890 data supplied to the INET loop is defined according to the assignment made via
1 SIG 1 1 To use "Signal 2" data instead, signal reassignment is done at the HP 5890.
As an example, a key sequence to assign detector B data to the Signal 1 output channel would
be:
[ SIG 1 1 f
B 1 [ ENTER
I
For more information about INET, refer to the HP 5890 SERIES II Reference Manual and the
reference manuals for your HP integrator/controller.
Controlling Signal Output 6-14
Contents
Chapter 7:
Making a Run
Starting/Stopping a Run
INET Start/Stop Operation
Status LEDs
Using the Time Key
Using Single-Column Compensation
Displaying Column Compensation Status
Initiating a Column Compensation Run
Assigning Column Compensation Data
Using Instrument Network (INET)
Using Timetable Events
Turning Valves On/Off During a Run
Switching Signals During a Run
Changing TCD Sensitivity During a Run
Modifying Timetable Events
7-1
7-1
7-2
7-6
7-8
7-9
7-10
7-12
7-14
7-15
7-18
7-20
7-22
7-23
Making a Run
This chapter includes information regarding starting and stopping an analytical run, using
timetable events, and making a single-column compensation (SCC) run.
Starting/Stopping a Run
Pressing ( START 1 starts the oven temperature program, run clock, and timed events.
Also, a remote start relay is momentarily closed to start a remote device such as an integrator.
For a strip chart recorder, a tick mark is produced to mark the beginning of a run.
Pressing 1 START \ lights the green RUN LED. Yellow OVEN LEDs are lit to follow progress
through an oven temperature program. The red NOT READY LED lights during a run ONLY
if some part of the system becomes not ready (see STATUS LEDs on next page).
1 START 1 aborts a keyboard entry in progress by causing a run to begin immediately, t START >
itself is inactive if the RUN LED is on or blinking.
Pressing t ST0P 1 terminates a run. For a strip chart recorder, a tick mark is produced to mark
the end of a run.
INET Start/Stop Operation
Normally, when the HP 5890 SERIES II (hereafter referred to as HP 5890) and integrator/
controller are connected together via INET, 1 START > a m j 1 STOP I o n either instrument are
equivalent. The only exception to this is if INET is turned OFF (LOCAL) at the HP 5890:
if INET is off, HP 5890 1 START 1 a n d [ STOP 1 k e y s a r e independent of those on the
integrator/controller. This permits starting the HP 5890 without simultaneously starting the
integrator/controller. (See the HP 5890 SERIES II Reference Manual for details regarding
switching INET on or off).
Note: The HP 5890 I ST0P 1 key is always active during a run if the run must be aborted at the
HP 5890.
Making a Run
7-1
Status LEDs
Readiness occurs when the oven is on and at its setpoint temperature, when heated zones that
are on are at their respective setpoint temperatures, and when any detector assigned to an
output signal channel is ON.
Any temperature not at setpoint causes the red NOT READY LED to be lit until setpoint is
achieved.
In addition, there is an external readiness input, and an INET readiness input. If a connected
external device is not ready, the NOT READY LED is lit.
If the NOT READY LED is continuously lit, any item(s) preventing readiness can be determined by pressing t CLEAR 1: the display cycles, giving an appropriate message for each item.
Making a Run
7-2
Typical NOT READY Displays (obtained by pressing [CLEAR 1 )
| CLEAR | Disolavs
Outside a Run:
ACTUAL
OVEN TEMP
NOT
SETPOINT
BEADY
ACTUAL
)N4 A
TEMP
NOT
TB/IP
NOT
NOT
ON
NOT
Assigned detector not turned
on
NOT
SETPOINT
RSAOY
ACTUAL
SYSTEM
SETPOINT
(SIG 1}
ACTUAL
©OT DEVICE
SETPOINT
READY
ACTUAL
BET A
- Temperature not at setpoint
READY
ACTUAL
tHET A
SETPOINT
Device external to HP 5890
signals not ready
SETPOINT
INIT system reports not ready
READY
During a Run:
ACTUAL
RUN
IN
ACTUAL
COMP
1
SETPOINT
Analytical run currently in
process
PROGRESS
BLANK
RUN
SETPOINT
A
Column compensation run
currently in progress
Note that the figure above shows typical normal displays occurring when various parts of a
properly operating HP 5890 system are not ready for initiating a run.
Making a Run
7-3
HP 5890 READY Display
ACTUAL
HP $890
SYSTEM
SETPOINT
RSAOY
For the oven and heated zones, their messages cease to be displayed once their respective
setpoint temperatures are reached. Once every item is ready, pressing 1 CLEAR ) results in the
display shown above.
Status LED Display
0
r
O
Off
/
(Jlinking )
"RUN"LED
^
LED on: indicates a run (either analytical or column compensation) is actively in progress.
Q
LED off: indicates no run currently in progress.
(3
LED blinking: waiting for HP 5890 readiness. A command
for a remote controlling device has been sent to start a run,
or a column compensation run is initiated, before the
HP 5890 is ready. Run begins automatically once readiness
is achieved.
-
Making a Run
On /
7-4
STATUS LED Displays (corf.)
"NOT READY" LED
on-One or more parts of the HP 5890 system reports not
ready. (CtEAR) displays what is not ready.
LED off: HP 5890 system is ready for initiating a run (either analytical
or column compensation) at any time.
LED blinking: Hardware fault.
i
I displays FAULT: messages.
i
The RUN LED is normally lit continuously whenever a run is in progress (either an analytical
or column compensation) and off when not in a run. It flashes when a column compensation
run is initiated before the HP 5890 is ready (e.g., oven or zones not at setpoint); the compensation run begins automatically upon readiness.
The RUN LED also flashes on and off in an INET-controlled system in automated operation
during times when the HP 5890 is waiting for some device in the system to complete its task
before starting the run (e.g., while waiting for automatic sampler operation, report printing,
computations, etc). Once the run begins, the LED is continuously lit.
Making a Run
7-5
Using the Time Key
Successively pressing! TIME 1 by itself displays various times related to analyses being performed
and also accesses a stopwatch timer useful in setting gas flow rates, measuring elapsed time
between events of interest, etc.
Typical time displays are shown in the figure below. Note that there are three possible functions
outside an analytical run (or column compensation run) and three possible during an analytical
run (or column compensation run). Each press of t TIME i rolls to the next function.
Typical Time Displays
Outside a Run:
ACTUAL
NEXT
RUN
243d
ACTUAL
t=S:10. 7
LAST
SETPOINT
MIN
SETPOINT
0.19
RUN
ACTUAL
SETPOINT
1&77
MIN
ACTUAL
SETPOINT
During a Run:
iiiiijiiiiiiiiiiii: | i | | | | | | | | | l l l l : | | | iii!
ACTUAL
SETPOINT
|!::|:||I|Il!lIli:iII|:i|i ||||;|||||::|||Iii||::iiiii
ACTUAL
ELAPSED
12.1S
SETPOINT
MIN
Time displayed for NEXT RUN or LAST RUN does NOT include C EQUIBTIME 1 , and does not
include cooldown time after completing an oven temperature program. It is simply total time
calculated for the analytical (or column compensation run) itself.
In stopwatch mode, both time (to 0.1 second) and reciprocal time (to 0.01 min" 1 ) are displayed
simultaneously. The timer is started by p r e s s i n g ^ ^ O ; it is stopped by pmssingfENTER 1 again.
Pressing I CLEAR 1 AFTER the timer is stopped resets the timer.
Making a Run
7-6
Note that other instrument functions may be accessed normally (e.g., [ OVEN TEMP 1 O r
without stopping or resetting the timer simply by pressing the necessary keys. The timer
continues to run but is not displayed until I T|ME 1 is again pressed.
I TIME 1 is also used in key sequences to time-program events during a analytical run (see" Using
Timetable Events" in this chapter).
Making a Run
7-7
Using Single-Column Compensation
The HP 5890 permits performing a chromatographic blank run (run made with no sample
injected), storing the data as a baseline profile.
Assuming the baseline profile is consistent from run to run, it may be subtracted from sample
run data to remove baseline drift (usually caused by column bleed).
Note: Single-column compensation data is valid only for a specific detector and column
combination operating under defined temperature and gas flow rate conditions. Invalid results
may occur if conditions by which blank run data is collected are different from conditions used
to collect sample run data.
Two separate profiles may be stored (designated by [ COLCOMPJ~1 or I COLCOMP2J ) ; as, for
example, one each for two different detectors or two profiles for the same detector but using
different chromatographic conditions.
Note: The HP 5890 t ST0P 1 key is always active during a column compensation run if the run
must be aborted at the HP 5890.
Making a Run
7-8
Displaying Column Compensation Status
Status of column compensation data is displayed by pressing either
rooLcoMP2 1 . The figure below gives typical displays:
or
Typical Column Compensation Status Displays
(Equivalent displays are possible
for COMP 2 and/or detector B)
SE
No baseline profile data is presently
stored for detector A in COMP 1.
SETPOINT
^
ACTUAL
OATA
OK
A
J
SETPOINT
TOO
STESP
b a s e | j n e p r o f i | e d a t a i s p r e s ently
stored for detector A in COMP 1
change in baseline slope exceeds
maximum value permitted.
Column compensation data may not be
valid.
Column compensation run aborted
prematurely via f ST0P J
Column compensation data may not be
valid.
each display, COMP 1 or COHP 2 echoes the key pressed
respectively); A or B indicates the assigned detector.
In
or
Making a Run
7-9
Initiating a Column Compensation Run
After entering the oven temperature program to be used for later sample runs, a column
compensation run is initiated by first pressing either [ COLCOMPI 1 O r [ COLCOMP2~~1 to display
current column compensation status and to designate where the new baseline profile is to be
stored.
•
If the desired detector (A or B) is displayed, the column compensation run is
initiated simply by pressing 1 ENTER 1.
•
If the wrong detector is displayed, press either A or B to assign the desired
detector, then press f ENTER 1 to initiate the column compensation run.
•
I • ) followed by I ENTER 1 initiates two parallel column compensation runs using
the same oven temperature program and storing a baseline profile for each of the
assigned detectors simultaneously.
This option is useful for sample analyses made using different detectors and/or columns but
using identical temperature programs.
Note: A device connected via the remote start/HP 5890 ready cable that is started from the
HP 5890 by a normal analytical run is NOT started by a column compensation run.
Additional detail concerning functions available at the REMOTE receptacle is found in the
HP 5890 SERIES II Site Prep and Installation Manual.
Messages listed in the next figure are displayed either while a column compensation run is in
progress or if there is a problem preventing the compensation run from starting.
Making a Run
7-10
Typical Column Compensation
Message Displays
liiiiiiiiiii:iiiiiiiiiiiiiiiiiiiiiiiiiiiil
ACTUAL
SETPOINT
liiiiliiiiliiiiiiP^Hii^nii
ACTUAL
SETPOINT
liiiiiiiiiiii•WIBililiHiiiIllllllj
ACTUAL
SETPOINT
S:W::;::™;SB;1
ACTUAL
ACTUAL
The oven is not on. Once the oven is
switched on, the column compensation run
begins automatically when the oven is equilibrated at its initial temperature setpoint.
An oven temperature program is not defined:
nnn7fiml RATE i setpoint value(s) must be
entered. The temperature program defined
should be that used for sample runs. No
column compensation run is performed.
Or detector B, chosen detector not switched
on. No column compensation run is performed.
SETPOINT
liiiHiiiiiiiiiiiiiiiiiiiiiiiiiiiiiIiiliij
ACTUAL
Displayed if an attempt to start a column
compensation run is made while a sample
run is in progress. No column compensation run is performed.
SETPOINT
iiiliij
liiiiiiiliii^
Comp run in progress. In this example,
data from detector A is stored as COMP 1
(accessed via I COL COMPI"1).
Or detector B, chosen detector not present.
No column compensation run is performed.
SETPOINT
No detector(s) present. No column compensation run is performed.
liiiiilliilii
ACTUAL
SETPOINT
iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiimmmd
Occurs if entering new oven temperature
program setpoints is attempted during a
column compensation run. Entries are
ignored. Also occurs if an attempt is made
to start a column compensation run while
one is already in progress. The one in progress continues to normal completion.
Making a Run 7-11
A column compensation run terminates automatically at completion of its oven temperature
program. Any existing baseline profile is erased as data for the new baseline profile is collected
and stored.
Note that the oven temperature program for a column compensation run follows setpoint
values for C INITTIME " j , I RATE 1 a n ( j [ FINAL TIME ~1 as in an analytical run. Data is stored,
however, only for t BATE 1 and [ FINAL TIME 1 portions of the temperature program.
A sample run cannot be started (via [ START 1) while a column compensation run is in progress.
[ STOP 1 aborts a column compensation run: The baseline profile stored is probably not valid
because the oven temperature program will not have reached the [ FINAL TEMP~~> setpoint.
A message WRONG TIME is displayed to indicate a mismatch has occurred between the
expected length of time for the run versus the actual time.
Assigning Column Compensation Data
After baseline data for a given detector (A or B) is stored as either COMP 1 or COMP 2, the
column compensation data must be assigned to a specific detector signal. During a run, the
compensation data is subtracted from run data for the SAME detector.
The following key sequence assigns such baseline-corrected data to a particular output channel:
detector
I
A I
or I
B
1
[
COLCOMPI"1
or
\
A~)
| -
1 [
COLCOMP1 1
[ ENTER
The figure below illustrates the resulting display confirming the assignment:
Making a Run
7-12
[
CQLCQMP2^
Column Compensation, Typical Display
SIGNAL
1
A
-
COMP
1
Note: There is NO internal verification by the HP 5890 to ensure that compensation data
collected on a given detector is later assigned to be subtracted from the SAME detector via the
above key sequence. If subtracting compensation data results in strange baseline behavior:
•
Compensation data itself is suspected.
•
Data acquired from a different detector has been assigned.
•
Chromatographic conditions used for sample analyses are different from those used
for the original column compensation run.
Once assignment is made to a particular output channel, sample analyses are performed in the
usual manner; the only difference is that the observed baseline should be relatively free of drift.
Making a Run
7-13
Using Instrument Network (INET)
Information about INET communications is available in chapter 6, "Controlling Signal Output"
and in the reference manuals for your integrator/controller.
Making a Run
7-14
Using Timetable Events
Timetable events are controlled through the keys shown.
Timetable Control Keys
TIME
i
OVEN
TEMP
TABLE
INIT
VALUE
ADD
DELETE
PREV
NEXT
INIT
TIME
RATE
FINAL
VALUE
FINAL
TIME
t
•
t
•iiiill
•iiii
The following is a list of HP 5890 events that can be controlled during a run.
•
Valves (On/Off)
•
Signal Switching (On/Off)
•
Changing TCD Sensitivity (High or Low)
•
Inverting TCD Polarity (-),Refer to chapter 6, "Inverting TCD Signal Polarity"
•
Split/Splitless Purge Flow On/Off, Refer to chapter 4, "Setting Splitless Mode
Flow "
Valves, signal switching and changing TCD sensitivity are covered in this section. Refer to
chapter 6 for information regarding inverting TCD polarity during a run. Refer to chapter 4
for information regarding turning split/splitless flow on/off during a run.
Making a Run
7-15
ACTUAL
SETPOINT
iliiiiiiiiiiiiiiiil
Use the table key to enter into the timetable. From _1
here, previous and next keys may be used to scroll
through an existing timetable. Add and delete keys
may be used to add or delete timetable commands.
After the TABLE key is pressed to enter the
timetable, use the ADD key to enter a timed
event. The timetable can hold up to 37
timed events.
After the TABLE key is pressed to enter
the timetable, use the DELETE key to remove a timed event.
PREVIOUS
After the TABLE key is pressed to enter
the timetable, use the PREVIOUS key to
scroll through the timetable toward the
HEAD OF TIMETABLE.
After the TABLE key is pressed to enter
the timetable, use the NEXT key to scroll - ^
through the timetable toward the END OF 37
TIMETABLE.
•EAR 1 After timetable entries have been made, (or
whenever working inside the timetable) use the
CLEAR key to exit timetable programming.
Note: The clear key does not delete any timetable events.
Making a Run
7-16
An example key sequence to create a timetable event:
or
ON)
TABLE i
| ADD)
function key
action key
I TIME 1
time value
t
C PURGE/VALVE
i
(Valve 1, 2,3 or 4 )
Signal Switch = [ SIGI I or
[
TCP SENS
1
CLEAR \ exits the timetable and returns the keyboard to normal operation
Note: Refer to "Inverting TCD Signal Polarity"
in chapter 6 for time programming TCD polarity.
Making a Run
7-17
Turning Valves On/Off During a Run
For information on controlling splitless purge flow during a run, refer to chapter 4, "Setting
Splitless Mode Flow".
Control of up to four gas/liquid sampling valves (designated as valve 1, 2, 3, and 4) may occur in
either of two ways. The operator may switch the valves manually whenever it is desirable via
keyboard entry, or more conveniently, the valves can be switched ON and OFF during a run via
the HP 5890's timed events table.
For example, to create a timetable event to turn valve 2 on at 1 minute into a run, enter the key
sequence:
1,2, 3 or 4
rofn or
\
llJjgjjjjJUiJ
[ TABLE 1
^ADDj
[
PURGE/VALVE
"j
/
[ 2 1 [ ON |
[^TIME_J
I 1 1
[ ENTER 1
Note: If the valve is already in the position where a command instructs it to switch, no action
will occur.
The designated channels (1, 2, 3, or 4) are determined solely by the wiring connections to the
valve box.
A valve will reset automatically at the end of each run if a valve timetable is set. If the last
switching mispositioned the valve and the valve does not reset, reset the valve position
manually before starting a new run.
Making a Run
7-18
One way of resetting the valve automatically after the useful run time is to program the valve.
For example, on a two-valve system, where valve 1 is a gas sampling valve and valve 2 is used for
venting, it may be desirable to: 1) inject from valve 1 at the beginning of the run (run time
0.00); 2) vent the last part of the sample, using valve 2, at 2-3/4 minutes (run time 2.75); or
3) relax both valves just prior to the end of the run (determined to be a run time of 40.00).
To perform the above example, enter the following commands:
TABLE 1 [ADD | [
PURGE/VALVE
[ADD | [
PURGE/VALVE
[ADD | [
PURGE/VALVE
[ADD | C
PURGE/VALVE
1
[ ON [
TIME
[OFF I
TIME
Making a Run
7-19
Switching Signals During a Run
Some analyses require the use of more than one detector to completely characterize a given
sample. In situations were the analytical system can be configured to avoid coelution, switch
signals during a run to integrate the output into a single channel system. Signal switching can
be accessed only as a timetable event.
Switching signals replaces the I
for a specified period of time.
I definition to whatever is currently assigned to
[ RANGE 2T()
1
[ RANGE 2T()
1
ATTN2T0
1
LATTN2TO
1
Signal Switch On Time
Signal Switch Off Time
Run Time
Note:
Making a Run
[ ATTN2••
on the HP 5890 has no effect when using an
electronic integrator. Attenuation is controlled locally at the integrator.
The
7-20
For example, to create a timetable event to switch signals at 1 minute into a run, enter the key
sequence:
During a run, at the signal switch on time. (""sis 1 1 will switch automatically to monitoring the
device assigned tnt siG2 1 xhe run will continue in this manner until a signal switch off time is
reached or the run ends. Signal assignments reset automatically at the end of each run.
Depending on the analyses, baseline upsets may be seen when signals are switched. These
upsets will become more of a problem when high sensitivity is required. Adjust [ ATTN2T0 1 ,
1 ZER0 or L RANGE 2T0 ~*i if necessary to minimize the upset.
Making a Run
7-21
Changing TCD Sensitivity During a Run
Two TCD sensitivity (signal amplification) settings are available, controlled through the keyboard
([ON} =HI and («£) =LOW).
The high-sensitivity setting increases sensitivity (area counts observed) by a factor of 32 and is
usable in applications where component concentrations are < 10%.
Components that are more concentrated may exceed the output range for the TCD, causing flattopped peaks. If this occurs, the low sensitivity setting should be used instead.
The sensitivity setting may be changed from one setting to the other at any time during a run
through a timetable event.
For example, to create a timetable event to change the TCD sensitivity from Low to Hi
at 1 minute into a run:
either detector
I A\
Low = (°ED High =
or P L
\
TABLE 1
| ADD \
[
TCD SENS
1
/
I
A \
| ON |
[
TIME
Sensitivity returns to its original state automatically at the end of the run.
Making a Run
7-22
Modifying Timetable Events
Example Timetable Event
FUNCTION
TIME
r
i
VALVE 1
1.00
ON
Timetable events can be changed in three ways: by adding new entries, by deleting existing
entries or by modifying the time value of a timed event.
New entries are added by using the same key sequences used to create a table in the first place:
liiajiji [ TABLE 1 | ADD |
followed by a valid timetable event
To delete a single timetable event, first display the event by pressing:
l i p S i j 1 TABLE |
(followed by [
PREVIOUS
~~j or I
NEXT
1 when needed)
While the particular event is displayed, delete the event from the timetable by pressing:
[ DELETE 1
1
ENTER
1
The instrument will respond, DELETED.
To modify the time associated with an event, first display the event by pressing:
p;pa;j;$ [ TABLE 1
(followed by (
To modify the time press: I
TIME
PREVIOUS
1 or [
NEXT
) when needed)
1 followed by the new time value, I ENTER 1
The instrument will respond, MODIFIED.
For example, to change VALVE 1 ON
1.00 is displayed) the key sequence is:
1.00 to
VALVE 1 ON
2.00, (while VALVE 1 ON
The result is valve 1 will turn on at 2 minutes rather than 1 minute.
Making a Run
7-23
Contents
Chapter 8: Storing and Loading HP 5890 SERIES II Setpoints
Storing GC Setpoints
Loading GC Setpoints
8-1
8-2
8
Storing and Loading
HP 5890 Series II Setpoints
Up to three sets of GC setpoints may be stored in the HP 5890 Series II (hereafter referred to
as HP 5890). GC setpoints include any entry made through the HP 5890 keyboard. These sets
of GC setpoints are stored in storage registers designated as 1, 2, or 3.
Storing GC Setpoints
To store a set of setpoints currently in the HP 5890 into a storage register, use the following key
sequence:
register 1, 2, or 3
\
Storing Setpoints
8-1
Loading GC Setpoints
WARNING
BE CAREFUL WHEN LOADING GC SETPOINTS FROM A STORAGE
REGISTER. STORED SETPOINTS MAYTURN DETECTORS ON OR SET
HIGH OVEN TEMPERATURES WHICH, WITHOUT PROPER GAS FLOW,
COULD DAMAGE A DETECTOR OR COLUMN.
To load a set of setpoints already stored in one of the storage registers, the key sequence is:
register 1, 2, or 3
\
Loading setpoints replaces all the setpoints currently defined in the HP 5890 with the setpoints
in the storage register selected.
As a guide to recording GC setpoints stored in storage registers, the following pages may be
photocopied and used to record a list of setpoints before they are stored. Keep these lists for
your records when preparing to load setpoints.
Storing Setpoints
8-2
Storage Setpoint Log
INJATEMP
1
INJ B TEMP
I
[ PET A TEMP
1
[
[ PET B TEMP
1
[
AUX TEMP
1
[
EQUIB TIME
1
[
OVEN MAX
OVEN TEMP
[
INIT VALUE
1
[ RANGE 2 T ( T l
I ZERO 1
[ATTN2T0
1
_
[
PURGE/VALVE
^
[
PURGE/VALVE
1
[
PURGE/VALVE
1
[
PURGE/VALVE
1
[
PURGE/VALVE
1
PURGE/VALVE
[ CRYOPARAM
1
[ COL COMP1
1
[ COLCOMP2
1
[
FLOW PARAM
1
[ TCP SENS
Storing Setpoints
8-3
Storage Setpoint Log (continued)
[ OVEN TRACK
[
1 [ ON | | OFF
INJATEMP
1
INIT VALUE
[
INITTIME
1
[ FINAL VALUE
1
[ FINAL VALUE 1
I
A
FINAL VALUE
[
FINAL TIME
1
I
1
[
A
FINAL TIME
[
INJBTEMP
1
[
INIT VALUE
1
[
INITTIME
1
[
A
[ FINAL VALUE
1
FINAL TIME
FINAL VALUE
FINAL TIME
[
INJAPRES
1
[
INIT VALUE
1
[
INITTIME
[ FINAL VALUE
1
[ FINAL VALUE 1
I
A
[ FINAL VALUE 1
|
[
1
[
|
A
[
f~i~
FINAL TIME
[
INJ B PRES
1
[
INIT VALUE
1
[ FINAL VALUE
1
FINAL TIME
Storing Setpoints
8-4
FINAL TIME
1
FINAL TIME
1
[ FINAL VALUE 1
I
A
[ FINAL VALUE 1
I
|
A
[
FINAL TIME
1
FINAL TIME
1
B
( B
(~g~
Storage Setpoint Log (continued)
Time Table Events:
Storing Setpoints
8-5
Contents
Chapter 9: Controlling Valves
I
SW/
Turning Valves On/Off Manually
9-2
9
Controlling Valves
Control of up to four valves (designated as valve 1, 2, 3, and 4) may be accomplished in two
ways.
• During a run (see chapter 7, "Turning Valves On/Off During a Run")
• Manually through keyboard entry as described in this chapter
Note: If the valve is already in the position where a command instructs it to switch, no action
will occur.
The following figure illustrates some examples of the HP 5890 SERIES II (hereafter referred to
as HP 5890) alphanumeric display for listing current valve status or verifying the timed events
table to switch the valve during a run.
ACTUAL
SETPOINT
ACTUAL
SETPOINT
••••••••a
VAUVE 1 OFf
j
Typical Valve Status Displays
Controlling Valves
9-1
Turning Valves On/Off Manually
The designated channels (1, 2, 3, or 4) are determined solely by the wiring connections to the
valve box. However, often valves will be located as shown in the figure below.
Top View
Valve
Locations
•B"
(§)
"A" (Q)
Front
Valve Locations
Controlling Valves
9-2
Valves may be switched from the keyboard at any time by pressing the key sequence:
Valve 1,2,3 or 4
(~QN1 or f ° ^ n
\
i
[
PURGE/VALVE
J
| 2 \
| ON 1 [ ENTER
To display the current status of a valve, press:
Valve 1,2, 3 or 4
\
[
PURGE/VALVE
1
If the HP 5890 display is already displaying the appropriate addressed valve, the operator need
only press the ON or OFF key to activate or relax the displayed valve.
A valve resets automatically at the end of each run. If the last switching mispositioned the valve
for the start of the next run, the valve position will reset at the end of the run.
Controlling Valves
9-3
Contents
Chapter 10: Using Electronic Pressure Control
/
>«—>
\^_^
v
What Is Electronic Pressure Control?
Using Electronic Pressure Control with Inlets (EPC)
Using Electronic Pressure Control with Detectors (Auxiliary EPC)
Safety Shutdown for Electronic Pressure Control
What Happens During Electronic Pressure Control Safety Shutdown?
Summary Table of Safety Shutdown
Setting Inlet Pressure Using Electronic Pressure Control
Zeroing the Pressure
Setting Constant Flow Mode
Setting Inlet Pressure Programs
Checking Inlet Pressure Programs
Setting Pressure Using Auxiliary Electronic Pressure Control
How Do I Access Auxiliary Electronic Pressure Control?
Setting Constant Detector Pressure
Setting Detector Pressure Programs
Checking Detector Pressure Programs
Suggested Ranges for Operating Auxiliary Electronic Pressure Control
Using Electronic Pressure Control to Control Gas Flow
Accessing the Flow Parameter Displays
Selecting the Gas Type
Setting the Column Diameter
Setting the Column Length
Using Vacuum Compensation Mode
Using Constant Flow Mode for Inlets
Setting Mass Flow Rate for Inlets
Setting Inlet Flow Programs
Setting the Average Linear Velocity
Understanding Average Linear Velocity
Calculating Outlet Flow
Setting the Average Linear Velocity
Determining the Corrected Column Length
Packed Column Considerations
Capillary Column Considerations
Optimizing Splitless Injection Using
Electronic Pressure Control
Operating the Gas Saver Application for the Split/Splitless Inlet
10-1
10-2
10-2
10-4
10-4
10-5
10-6
10-6
10-8
10-9
10-11
10-12
10-13
10-14
10-15
10-16
10-17
10-22
10-24
10-25
10-26
10-26
10-27
10-28
10-29
10-30
10-32
10-32
10-33
10-33
10-34
10-34
10-34
10-36
10-38
What Is the Gas Saver Application?
What Are the Required Settings for Operation?
How Is the Gas Saver Application Configured?
How Does the Gas Saver Application Operate?
Zero the Channel
Enter the Carrier Gas Pressure
Enter the Column Parameters
Set the System to Operating Conditions
Set the System to Off-Hour Conditions
Recommended Flow Rates for Inlet Systems
Using the Gas Saver Application
Additional Benefits of the Gas Saver Application
Using the External Sampler Interface
Which Configuration Should I Use?
Using the External Sampler Interface with an Inlet as a Heated Zone
Special Considerations
Using Valve Options
Which Valves Work Best with Auxiliary Electronic Pressure Control?
10-38
10-38
10-39
10-40
10-40
10-41
10-41
10-42
10-42
10-43
10-43
10-44
10-44
10-54
10-54
10-57
10-60
10
Using Electronic Pressure Control
What Is Electronic Pressure Control?
The electronic pressure control (EPC) option for the HP 5890 Series II Plus GC allows you to
control the inlet and auxiliary gases from the keyboard.
You access the inlet and auxiliary detector gases by pressing one of the key sequences shown in
the following table. The keys you press depend on how your GC is configured. For example, if
auxiliary channel C is programmed to control the makeup gas for detector A, you would access
the auxiliary EPC channel C to access control of that gas.
Press:
To Access:
Injector A pressure
— EPC Controls Inlet Gas
Injector B pressure
Auxiliary EPC channel C
Auxiliary EPC channel D
Auxiliary EPC channel E
Auxiliary EPC
Controls Detector Gas
Auxiliary EPC channel F
With EPC, inlet and detector pressures can be either constant or programmed. The following
sections describe the benefits of using EPC for inlets and detectors.
Using Electronic Pressure Control 10-1
Using Electronic Pressure Control with Inlets (EPC)
EPC of inlets provides very accurate and precise control of column head pressure, typically
resulting in retention time reproducibility of better than 0.02% RSD when no column effects
are present. With EPC, you can set constant pressure and pressure programs through the
keyboard. Inlet pressures can also be set to maintain a desired column flow rate when the
column parameters have been entered.
Using Electronic Pressure Control with Detectors (Auxiliary EPC)
Auxiliary EPC allows you to control detector gases electronically. With auxiliary EPC, you can
set constant pressure and pressure programs through the keyboard. Auxiliary EPC is provided
by the combination of new, electronically controlled flow modules for gases and the PC board
capability to control those modules.
Auxiliary EPC of detector gases allows you to program the makeup gas to optimize a detector's
performance. With auxiliary EPC, you can control:
• All detector gases, including makeup, carrier, and fuel gases
• Gas flow to an external sampling device, such as a purge and trap or headspace system
• Gas flow through the split vent of a split/splitless inlet, which can save gas and optimize the
operation of the inlet (see "Operating the Gas Saver for the Split/Splitless Inlet" in this
chapter)
The following table shows the multiple uses of EPC for inlets and auxiliary EPC for detectors:
Uses for EPC and Auxiliary EPC
EPC
Auxiliary EPC
Head Space
•
•
Purge and Trap
•
•
Gas Saver
Thermal Desorption
•
•
•
Note: All HP 5890 instruments built before July 1, 1990, will display the message Change EPC
ROM when used with EPC. When this occurs, contact a Hewlett-Packard service representative
to upgrade and install the new ROM.
Using Electronic Pressure Control 10-2
For additional EPC information, see the HP application note "Analysis of Oxygenates in
Gasoline, Including ETBE and TAME, Using Dual-Channel Electronic Pressure Control,"
HP Application Note 228-174, publication no. (43) 5091-4701E.
This chapter is divided into several sections, including general EPC instructions, optimization
information for inlets, and optimization information for detectors. Specifically, this chapter
provides operating and optimization information for the following EPC systems:
• Split/splitless capillary inlet with EPC
• Septum purged packed Inlet with EPC
• Auxiliary EPC of detector gases
• Auxiliary EPC with Gas Saver for the split/splitless inlet
• Auxiliary EPC with external sampling devices
Operating information for the programmable cool on-column inlet is provided in a separate
manual included with the manual set. The following table describes the features that are
available for specific uses and applications of EPC:
Features of Electronic Pressure Control
Constant Pressure Constant Set Mass Flow** SetAvg.
Pressure
Vacuum
Controlled Function Pressure Programs Flow Mode Flow Rate Programs Linear Velocity Comp.*
Split/Splitless Cap.
Inlet (Carrier Gas)
•
•
•
•
•
•
•
Septum PP
Inlet (Carrier Gas)
•
•
•
•
•
•
•
Programmable
Cool On-Column Inlet
•
•
•
•
•
•
•
Auxiliary EPC
(Detector Gas)
•
•
Auxiliary EPC
(Gas Saver)
•
•
Auxiliary EPC
(General Purpose)
•
•
^Auxiliary inlet channel will calculate the vacuum compensation.
**You enter the required pressures.
Note: Constant flow mode is recommended for use with 530 \i capillary columns. For packed
columns, you must calibrate for each individual column to correct for different column lengths
and possible settling of the column packing.
Using Electronic Pressure Control 10-3
Safety Shutdown for Electronic Pressure Control
Systems equipped with EPC have a safety shutdown feature to prevent gas leaks from creating
a safety hazard. The safety shutdown feature is designed to prevent an explosive concentration
of hydrogen carrier gas from accumulating in the GC oven if a column breaks.
Back pressure regulated inlet systems (split/splitless capillary inlet) with EPC cannot detect a
column leak, however, because a column leak would occur before the gas reaches the EPC
valve. These systems limit the leak rate into the oven using the total flow controller. Under
these conditions, hydrogen diffusion out of the oven is fast enough to keep hydrogen concentration below the 4.1% lower explosion limit.
What Happens During Electronic Pressure Control Safety Shutdown?
If the system cannot reach a pressure setpoint, the system beeps. After about 2 minutes, the
beeping stops and the following message appears on the display:
ACTUAL
SETPOINT
EPP8: SAFETY SHUTDOWN
The system shuts down by entering a pressure setpoint of zero for the affected channel, turning
off all heated zones, and locking the keyboard. The table on the following page summarizes the
safety shutdown.
Using Electronic Pressure Control 10-4
Summary Table of Safety Shutdown
Summary Table of Safety Shutdown
What channels can shut down?
The system can shut down all inlet and auxiliary channels.
When does the system start beeping?
The beeps start 10 seconds after the pressure falls below
0.1 psi of setpoint.
What is the frequency of the beeping?
The system beeps at 10,40,60, 70, 79,87, 94,100,105,
109,112,114,115,116,117,118,119, and 120 seconds.
When does the system stop beeping?
The beeps stop 120 seconds after the system falls short of
the setpoint pressure. The actual safety shutdown begins.
What happens after the safety
shutdown occurs?
1. The keyboard locks.
2. All heated zones are turned off.
3. The oven fan is turned off.
4. The GC display shows the shutdown message.
5. The other pressure setpoints do not change.
6. The setpoint of the affected EPC channel is set to 0.0.
Note: These safety shutdown procedures apply to EPC boards with a mainboard ROM of
HP part number 05890-80310 or higher.
Using Electronic Pressure Control 10-5
Setting Inlet Pressure Using Electronic Pressure Control
If your GC is equipped with EPC, you can set constant pressure or create a pressure program
with multiple ramps. The following procedures will show you how to:
• Zero the pressure sensor in all channels and depressurize the system
• Set and maintain a constant pressure
• Set a pressure program using one or two ramps
• Check your pressure program
For more information on setting inlet pressures, see chapter 4, "Setting Inlet Pressure."
Zeroing the Pressure
The EPC system is zeroed before shipping, but you should check it periodically, especially when
ambient laboratory conditions change dramatically. Zero the instrument 30 to 60 minutes after
the system has heated up to allow for electronic drift.
To zero an EPC channel:
1. Turn off the inlet and detector gases. With zero pressure, remove the inlet septa and
depressurize the inlet.
Note: If the detector gas valves are closed, you will not be able to depressurize the system.
Note: When EPC is part of a GC-MS system, zero the pressure when either the MS pump
is off or the column is not connected to the inlet. Otherwise, the vacuum pump will lead to
miscalibration.
2. Use the steps below to zero channels A through F:
• To zero channel A:
a. Press: Pi&TO [ INJATEMP "1 | o | 1 • \ I o I I ENTER I Sets the inlet A pressure to 0.0
Allow enough time for the column to completely depressurize.
b. Press: PsapSft I 2 1 [ ENTER 1
value
[ ENTER 1
where value is the zero offset value shown on the GC display labeled "actual."
Using Electronic Pressure Control 10-6
To zero channel B:
a. Press: E&J$MI [
INJBTEMP
1 I o 1 I • 1 1 o 1 [ ENTER | Sets the inlet B pressure to 0.0
Allow enough time for the column to depressurize completely.
b. Press:
E W
(~s~> t ENTER 1
vaiue
[ ENTER 1
where value is the zero offset value shown on the GC display labeled "actual."
To zero channel C:
a. Press:
Illtiil
I A \ | o \ \ • \ | o ) [ ENTER I
Sets channel C pressure to 0.0
Allow enough time for the system to depressurize completely.
where value is the zero offset value shown on the GC display labeled "actual."
To zero channel D:
a. Press: M M
I
B
) 1o| I
I 1 o I I ENTER 1 Sets channel D pressure to 0.0
Allow enough time for the system to depressurize completely.
b. Press:
itJBii
l~s~> 1 ENTER 1
va/Me
[ ENTER 1
where value is the zero offset value shown on the GC display labeled "actual."
To zero channel E:
a. Press: EIJ8MI t
COLCOMPI
1 f~o"
1 • I (~°~> 1 ENTER 1 sets channel E pressure to 0.0
Allow enough time for the system to depressurize completely.
where value is the zero offset value shown on the GC display labeled "actual."
To zero channel F:
a. Press: PSSJaia [
COLCOMP2
1 | o \ 1 • 1 I o I I ENTER 1 sets channel F pressure to 0.0
Allow enough time for the system to depressurize completely.
where value is the zero offset value shown on the GC display labeled "actual."
Using Electronic Pressure Control 10-7
Setting Constant Flow Mode
While using constant flow mode, the pressure will change if the oven temperature changes to
keep the flow constant. When you select constant flow, you can set an initial pressure (at oven
initial temperature) and the GC maintains the initial flow throughout the run by adjusting
pressure continuously and automatically. This example shows how to set the inlet B pressure at
10 psi.
1. Use the following steps to turn on the constant flow mode:
a. Press: P1J8JJ81 I FLOW 1 to access the flow parameters display.
b. Continue to press [ FLOW 1 until you see the constant flow display.
ACTUAL
SETPOINT
EPPB CONST FLJGW OFF
c. Press:
to turn the constant flow mode on.
2. Press: ii®
INJBTEMP
J
|
ACTUAL
1 1
|
0 I
I ENTER
Sets the inlet B pressure to 10 psi
SETPOINT
The GC display looks like this
3.
Press:
[
INITTIME
1
[ e |
| s )
ACTUAL
| o |
(ENTER
Sets the initial time to 650 minutes (max.)
SETPOINT
The GC display looks like this
Inlet B at Constant Pressure
20 psi
-
15 psi
-
10 psi
Opsi
-
I
3
1
I
2
i
i
I
3
5
4
Minutes
i
i
i
6
7
8
I
9
10
Note: Inlet B will stay at 10 psi until the oven temperature changes. Then the pressure will
increase to keep the flow constant.
Using Electronic Pressure Control 10-8
Setting Inlet Pressure Programs
The run time of the analysis is determined by the oven temperature program. If the inlet
pressure program is shorter than the oven temperature program, the inlet pressure does not
remain at the last value but goes into constant flow mode for the remainder of the run. If the
oven temperature is changing, then the pressure will also change. To prevent a pressure
program from going into constant flow mode, set the pressure program longer than the oven
temperature program.
The following procedure shows how to create a pressure program with three pressure ramps for
inlet B.
1. Turn the constant flow mode off.
Note: For more information on setting constant flow mode, see "Using Constant Mass Flow
Mode for Inlets" later in this chapter.
2. Use the following steps to program the first pressure ramp:
The first pressure ramp starts at 10 psi for 1 minute, then ramps at 5 psi/min to 20 psi and
remains there for 2 minutes.
a. Press:
iiaijil
[
b.
Press:
[
INITTIME
c.
Press:
I "ATE 1
d.
Press:
[ FINAL VALUE
e.
Press:
[
INJ B PRES
1
I s~l
FINAL TIME
[
1
[
INIT VALUE
i ~ i) I ENTER 1
1
1
J
1 ENTER I sets inlet B pressure to 10 psi
Sets the initial time at 1 minute
Sets the ramp rate at 5 psi/min
I ENTER
Sets the final pressure at 20 psi
1
I 2 |
[ ENTER 1
Sets the final time at 2 minutes
3. Use the following steps to program the second pressure ramp:
The second pressure ramp starts at 20 psi and ramps at 2 psi/min to 26 psi. It remains at
26 psi for 2 minutes.
a. Press: 1
RATE
Sets the second ramp rate at 2 psi/min
b.
Press:
[ FINAL VALUE
Sets the second final pressure at 26 psi
c.
Press:
[
Sets the second final time at 2 minutes
FINAL TIME
Using Electronic Pressure Control 10-9
4. Use the following steps to program the third pressure ramp:
The third pressure ramp starts at 26 psi and ramps at 4 psi/min to 30 psi. It remains at 30 psi
for 2 minutes.
Sets the third ramp rate at 4 psi/min
a.
Press:
I RATE
b.
Press:
[ FINAL VALUE 1
| B
c.
Press:
[
I B )
FINAL TIME
1
Sets the third final pressure at 30 psi
[ 2 1 I ENTER 1
Sets the third final time at 2 minutes
The following graph shows the entire three-ramp pressure program.
Inlet B with 3 Pressure Ramps
Opsi
0
1
4
1
5
Using Electronic Pressure Control 10-10
r
6 7
Minutes
I
I
9
I
I
r
10 11 12 13
Checking Inlet Pressure Programs
1. Display the pressure program by pressing any pressure program key followed by [ ENTER 1.
2. Press 1 ENTER 1 successively to scroll through and view the pressure program.
Note: The oven program determines the run time of the analysis. If the inlet pressure program
is shorter than the oven temperature program, the inlet pressure goes into constant flow mode
for the remainder of the run. To prevent this, make sure that the inlet pressure program is
equal to or longer than the oven program.
Pressure Program
End of
Pressure
Program
Final
Value
End of
Oven
Program
i—i
Pressure
Rate
Init
Value
/
/
J
Init
Time
Rate A
11 Final
\ Value
Final
Time
Constant
Flow Mode
Run Time
Using Electronic Pressure Control 10-11
Setting Pressure Using Auxiliary Electronic Pressure Control
Auxiliary EPC is generally used for applications other than the control of carrier gas to the
column. The auxiliary channels (labeled C through F) do not use the pressure versus flow
calculations that the inlet channels have. Only pressure setpoints and programs are entered,
with flow values determined from the calibration curves established.
For applications such as detector gas control, where the restriction is provided mainly by a flow
restrictor in the detector block, the calibration curves are described by the following equation:
F = kxP M
Note: This is the equation used by the HP 3365 ChemStation for pressure versus flow
calculations with the auxiliary EPC channels. Values for the constants k and M are displayed on
the auxiliary pressure programs screen of the ChemStation when the calculations are carried
out. For term definitions, see your ChemStation manual.
Using Electronic Pressure Control 10-12
How Do I Access Auxiliary Electronic Pressure Control?
To access the auxiliary EPC channels, use the following keys at the GC keyboard:
Press:
To Access:
Auxiliary EPC channel C
Auxiliary EPC channel D
Auxiliary EPC channel E
Auxiliary EPC channel F
The pressure that you program at the keyboard is the pressure the HP
3365 ChemStation uses in its calculations. When operating under low
pressure, such as 15 psi, be sure to program the same pressure (15 psi)
at the keyboard. If the rate entered at the keyboard is higher, the
ChemStation will base its calculations on that rate, which may not be the
accurate flow through your system.
Using Electronic Pressure Control 10-13
Setting Constant Detector Pressure
This example shows how to set the auxiliary EPC channel C pressure at 10 psi. For additional
operating information, see chapter 5, "Operating Detector Systems."
0
1. Press:
ACTUAL
I
I ENTER
Sets auxiliary EPC channel C pressure to 10 psi
SETPOINT
illiiilll
2. Press:
[
The GC display looks like this
INITTIME
1
ENTER
[~i~
1
Sete the initial time to 650 minutes (max.)
SETPOINT
650.00
The GC display looks like this
Auxiliary EPC Channel C al Constant Pressure
20 psi
-
15 psi
-
10 psi
Opsi
0
i
1
I
i
I
I
4
5
Minutes
Using Electronic Pressure Control 10-14
i
i
I
10
Setting Detector Pressure Programs
The following procedure shows how to create a pressure program for auxiliary EPC channel C
with three pressure ramps. For additional operating information, see chapter 5, "Operating
Detector Systems."
1. Use the following steps to program the first pressure ramp:
The first pressure ramp starts at 10 psi for 1 minute, then ramps at 5 psi/min to 20 psi and
remains there for 2 minutes.
a. Press: M
A 1f
INIT VALUE 1
[ 1 1 1 o 1 [ ENTER"! Sets auxiliary EPC channel C initial
pressure to 10 psi
Press:
c.
Press: ( RATE 1 | s ) [ ENTER
d . Press:
[
INIT TIME
1 | [ ENTER
b.
[ FINAL VALUE ' j
e. Press: I FINAL TIME 1
Sets the initial time at 1 minute
Sets the ramp rate at 5 psilmin
| 2 1 | 0 1 [ ENTER
C O
t
ENT
Sets the final pressure at 20 psi
ER
Sets the final time at 2 minutes
2. Use the following steps to program the second pressure ramp:
The second pressure ramp starts at 20 psi and ramps at 2 psi/min to 26 psi. It remains at
26 psi for 2 minutes.
a. Press: I RATE
Sete the second ramp rate at 2 psi/min
b. Press: [ FINAL VALUE 1
[ A
c. Press: [ FINAL TIME 1
[ A
6 I I ENTER
Sefs the second final pressure at 26 psi
Sets the second final time af 2 minutes
Using Electronic Pressure Control 10-15
3. Use the following steps to program the third pressure ramp:
The third pressure ramp starts at 26 psi and ramps at 4 psi/min to 30 psi. It remains at 30 psi
for 2 minutes.
a. Press: 1 RATE
Sets the third ramp rate at 4 psi/min
b.
Press:
[ FINAL VALUE 1
c.
Press: I FINAL TIME
[B
Sets the third final pressure at 30 psi
PB 1
Sets the third final time at 2 minutes
The following graph shows the entire three-ramp pressure program.
Auxiliary EPC Channel C with Three Pressure Ramps
Rampi
30 psi
-
25 psi
-
20 psi
-
/
4 psi/min
2 psi / min
/
15 psi
Ramp
3
Ramp
2
-
/
10 psi
-
0 psi
~
0
I
1
5 psi / min
i
i
i
i
5
6
7
Minutes
i
I
I
10
11
12 13
Checking Detector Pressure Programs
To check your pressure program, press [ ENTER 1 successively to scroll through and view the
program immediately after setting it.
Using Electronic Pressure Control 10-16
Suggested Ranges for Operating Auxiliary Electronic Pressure Control
The following graphs show the ranges that Hewlett-Packard suggests to optimize the operation
of auxiliary EPC for detectors. The graphs show the flow restrictor you will need (the restrictors
are identified by colored dots) and the corresponding pressure versus flow relationship. Use the
table that most closely corresponds to the gas type you will use in your analysis.
Using Electronic Pressure Control 10-17
Auxiliary EPC Restriclor Kit
19234-60600 Green and Brown Dot
Computed nominal values at ambient temperature of 21 °C and pressure of 14.56 psia
Pressure
(kPa)
Pressure
(psig)
69.0
10
20
30
40
50
60
70
80
90
100
137.9
206.8
275.8
344.7
413.7
482.6
551.6
620.5
689.5
Helium Flow
(ml/min)
Nitrogen Flow Hydrogen
(ml/min)
Flow (ml/min)
20
45
76
111
22
50
87
131
182
239
300
366
437
513
190
232
275
321
Argon/Meth
Flow (ml/min)
19
21
45
76
110
148
188
229
273
318
363
42
99
170
251
344
442
549
666
786
901
150
Air Flow
(ml/min)
40
65
95
128
164
202
242
282
324
Flow Restrictor Data
19234-60600
700
Hydrogen/
600
>>Helium
/
500
Flow
ml/min
Air
/
Arg/Meth
300
200
100
20
40
60
Pressure, psig
Using Electronic Pressure Control 10-18
80
100
120
Auxiliary EPC Restrictor Kit
19231-60610 Brown Dot
Computed nominal values at ambient temperature of 21 °C and pressure of 14.56 psia
Pressure
(kPa)
Pressure
(psig)
69.0
137.9
206.8
275.8
344.7
413.7
482.6
551.6
620.5
689.5
10
20
30
40
50
60
70
80
90
100
Helium Flow Nitrogen Flow Hydrogen
(ml/min)
(ml/min)
Flow (ml/min)
76
174
302
457
634
838
1063
1310
1580
1873
150
344
596
896
1243
1634
2035
2456
2918
61
161
279
418
571
740
915
1101
1297
Air Flow
(ml/min)
Argon/Meth
Flow (ml/min)
65
157
273
410
561
726
900
1084
1278
1470
55
134
235
352
485
627
782
945
1110
1270
Flow Restrictor Data
19231-60610
1200
1000
Arg/Meth
Hydrogen
800
Flow
ml/min
400
200
20
40
60
80
100
120
Pressure, psig
Using Electronic Pressure Control 10-19
Auxiliary EPC Restrictor Kit
19243-60540 Green and Red Dot
Computed nominal values at ambient temperature of 21 °C and pressure of 14.56 psia
Pressure
(kPa)
Pressure
(psig)
Helium Flow
(ml/min)
69.0
10
7.2
17
29
44
137.9
20
206.8
30
275.8
344.7
40
50
413.7
60
Nitrogen Flow Hydrogen
(ml/min)
Flow (ml/min)
6.4
15
35
6.2
15
26
59
25
39
53
80
69
88
122
159
200
243
290
339
38
61
482.6
70
100
86
551.6
80
124
150
178
104
123
143
620.5
90
689.5
100
Air Flow
(ml/min)
14.7
Argon/Meth
Flow (ml/min)
52
67
84
101
120
139
5.7
13
22
33
46
59
74
89
106
123
Flow Reslrictor Data
19243-60540
250
Hydrogen /
200
Helium
/
/
150
Flow
ml/min
//
100
50
Nitroaen
Air
i
20
Arg/Meth
/
40
60
Pressure, psig
Using Electronic Pressure Control 10-20
80
100
120
Auxiliary EPC Restrictor Kit
19234-60660 Blue Dot
Computed nominal values at ambient temperature of 21 °C and pressure of 14.56 psia
Pressure
(kPa)
Pressure
(psig)
69.0
137.9
206.8
275.8
344.7
413.7
482.6
551.6
620.5
689.5
10
20
30
40
50
60
70
80
90
100
Helium Flow Nitrogen Flow Hydrogen
(ml/min)
(ml/min)
Flow (ml/min)
1.3
2.7
4.4
6.4
8.8
11.5
14.5
17.7
21.2
24.9
Air Flow
(ml/min)
Argon/Meth
Flow (ml/min)
0.9
2.0
3.4
5.0
7.0
9.2
11.7
14.5
17.5
20.6
0.9
1.9
3.2
4.8
6.4
8.4
10.5
12.9
15.5
18.4
2.0
4.6
8.1
12.3
16.9
22.2
27.9
34.5
41.5
49.7
1.0
2.1
3.6
5.4
7.4
9.7
12.3
15.2
18.3
22.0
Flow Reslrictor Data
19234-60660
25
/Hydrogen
/A
/
20
Arg/Meth
/
Flow
ml/min
Helium
Nitrogen
Air
15
/
/
10
/
20
y.
40
60
80
_ ._J
100
120
Pressure, psig
Using Electronic Pressure Control 10-21
Using Electronic Pressure Control to Control Gas Flow
With EPC, you can also control flow by setting the pressure. The following procedures will show
you how to:
• Access the flow parameter displays
• Select the gas type
• Set the column diameter
• Set the column length
• Use the vacuum compensation mode
• Set constant mode for inlets
• Set mass flow rate for inlets
Pressure is the parameter controlled and measured with the EPC system; however, the
corresponding column outlet flow rate and average linear velocity are also calculated and
displayed. Entries can be made in terms of velocity from which the system calculates the
required pressure and enters this setpoint.
The following example shows the relationship between pressure and flow for EPC systems. In
the first table, pressure is constant and the flow changes with temperature. In the second table,
flow is constant and pressure changes with temperature.
Using Electronic Pressure Control 10-22
Constant Pressure with Changing Flow
50
Temperature (°C)
3.6
Flow (ml/min)
100
2.8
150
2.3
200
1.9
250
1.6
300
1.3
Pressure (psi)
15
15
15
15
15
15
Linear Velocity (cm/sec)
51.1
46.3
42.4
39.1
36.2
33.7
Constant Flow with Changing Pressure
Temperature (°C)
Flow (ml/min)
50
3.6
100
3.6
150
3.6
200
3.6
250
300
3.6
3.6
Pressure (psi)
15
18
21.9
24
27.1
30.2
Linear Velocity (cm/sec)
51.1
55.1
58.3
60.9
63.1
65.0
Using Electronic Pressure Control 10-23
Accessing the Flow Parameter Displays
Use the following steps to access and scroll through the GC flow parameters displays.
1. Press: ElSaii^) t FLOW 1 to access the flow parameters displays.
2. Continue to press: I FLOW 1 to scroll through the flow parameter displays. The displays may
be in a different sequence depending on your configuration.
Flow Parameter Displays
ACTUAL
SETPOINT
Use this display to turn the constant
flow mode on or off.
CONST FtOW OFF
ACTUAL
He
SPPB
ACTUAL
EPPB
1
|
Split
0
Use this display to turn the vacuum
compensation mode on or off.
SETPOINT
Use this display to set the column diameter.
SETPOINT
Column ten 10.00 M
ACTUAL
Use this display to change the gas type.
SETPOINT
Column Dla ,530 mm j
ACTUAL
8:
HI
VAC COWP OFF
ACTUAL
8:
SETPOINT
Use this display to set the column length.
SETPOINT
Ml/Mln
Using Electronic Pressure Control 10-24
Use this display to set the mass flow rate.
Selecting the Gas Type
You will need to select or verify the gas type you are using for EPC applications. To select the
gas type:
1. Press: IMitil 1 FLOW \ to access the flow parameters display.
2. Continue to press: 1 FLOW 1 until the gas type appears on the GC display.
ACTUAL
SETPOINT
EPPB
The GC display now looks like this.
3. Press the number corresponding to the gas type you want to use. The chart below lists the
gas types available:
Gas Type
1
2
3
4
Helium
Nitrogen
Hydrogen
Argon/Methane
The number and gas you select will appear under the "setpoint" column on the GC display:
ACTUAL
EPPB
SETPOINT
The GC display now looks like this.
Using Electronic Pressure Control 10-25
Setting the Column Diameter
To set the column diameter:
1. Press: E-JSpaSJl [
) t 0 access the flow parameters display.
FLOW
2. Continue to press: I FL0W 1 until you see the column diameter display.
ACTUAL
S:
Column Dla
SETPOINT
,XXX
The GC display looks like this.
3. Enter the column diameter in \i (such as 200 [i, 320 \i, 530 (i). The example below shows the
column diameter for a 530 \i column.
Press:
[
o )
ENTER
ACTUAL
8:
Column Dla
|
Sets the column diameter to 530 fi.
SETPOINT
.530 mm
The GC display looks like this.
Setting the Column Length
If you do not know the exact column length or if you are using a packed column, follow the
steps described in "Determining the Corrected Column Length" later in this chapter. To set the
known column length in meters:
1. Press: Jg&SiiJl [
FLOW
\ to access the flow parameters display.
2. Continue to press: I FL0W 1 until you see the column length display.
ACTUAL
SETPOINT
The GC display looks like this.
3. Enter the column length in meters.
Press: I
2
I
I
5
I
t ENTER 1
ACTUAL
8:
Sets the column length to 25 meters.
SETPOINT
Column tort 2S,00M
Using Electronic Pressure Control 10-26
The GC display looks like this.
Using Vacuum Compensation Mode
Use vacuum compensation mode when you are using a mass spectrometer to correct for the
column outlet pressure. Using the vacuum compensation mode ensures that the constant flow
mode, calculated column flow, and average linear velocity are correct.
1. Press: PiP&iJi I FLOW l to access the flow parameters display.
2. Continue to press: 1 FLOW \ until you see the vacuum compensation display.
ACTUAL
SETPOINT
11111111
The GC
display looks like this.
3. Use one of the following steps to turn the vacuum compensation mode on or off:
a. Press: 1 ON 1 to turn vacuum compensation mode on.
After you select vacuum compensation, set the desired pressure. For more information
on setting the inlet pressure, see "Setting Inlet Pressure Using Electronic Pressure
Control" earlier in this chapter.
b. Press: I OFF 1 to turn vacuum compensation mode off.
Using Electronic Pressure Control 10-27
Using Constant Flow Mode for Inlets
Before setting the constant flow mode for inlets, you must first select the gas type. See
"Selecting the Gas Type" earlier in this chapter for more information.
Note: The initial pressure changes when you turn the constant flow mode on or off. Enter the
desired initial pressure after selecting constant flow mode. Also, make sure that the oven is
equilibrated to the initial temperature. If you set the initial pressure before the oven reaches
the initial oven temperature, the flow will be incorrect.
To use constant mass flow mode:
1. Press: E8ii8Sll [ FLOW \ to access the flow parameters display.
2. Continue to press: 1FL0W 1 until you see the constant flow display.
ACTUAL
SETPOINT
EPPB CONST FUQW OFF
3. Use one of the following steps to turn the constant flow mode on or off:
a. Press: I °N 1 to turn the constant flow mode on.
When you select on, you can set an initial pressure (at oven initial temperature) and the
GC maintains the initial flow throughout the run by adjusting pressure continuously and
automatically.
b. Press: ( OFF 1 to turn the constant flow mode off.
You must select off if you want to create independent pressure programs.
Using Electronic Pressure Control 10-28
Setting Mass Flow Rate for Inlets
When a pressure is set, the mass flow rate is displayed. Entering a new mass flow value sets a
new pressure automatically to produce the flow value entered.
1. Enter the correct gas type, column diameter, and column length. For more information on
setting the correct column parameters, see the appropriate sections earlier in this chapter.
2. Use the following steps to set the inlet B mass flow rate to 10 ml/min:
a. Press: I CLEAR > .
b. Continue to press: I FL0W ) until you see the mass flow control display.
ACTUAL
COLUMN B
.000
SETPOINT
ml/m!n
The GC display looks like this.
c. Press: I 1 1 1 o 1 I ENTER 1 to set the inlet B flow to 10 ml/min.
Note: Inlet B pressure will change to the value needed to produce a mass flow of
10 ml/min.
Using Electronic Pressure Control 10-29
Setting Inlet Flow Programs
You can use EPC to set flow programs indirectly by setting an inlet pressure program. The
following example shows how to obtain the pressure values necessary to set a pressure program
that results in the desired flow programs.
1. Enter the correct gas type, column diameter, and column length. For more information on
setting the correct column parameters, see the appropriate sections earlier in this chapter.
1. Press: I CLEAR I .
2. Continue to press: t FLOW ) until you see the mass flow control display.
ACTUAL
COLUMN B
3. Press:
SETPOINT
.XXX ml/min
ENTER 1
to set the inlet B initial flow to 4 ml/min.
ACTUAL
COLUMN B
4. Press:
4.0
C
The GC display looks like this.
INJ B TEMP
SETPOINT
ml/mln
The GC display looks like this.
1
ACTUAL
iiiii
liiiii
The GC display looks like this.
This will be injector B pressure initial value.
5. Press: I FLOW I repeatedly until you see the mass flow control display.
ACTUAL
COLUMN B
4,0
SETPOINT
nWmlrt
Using Electronic Pressure Control 10-30
The GC display looks like this.
. ENTER I to set the inlet B flow to 7 ml/min.
6. Press:
ACTUAL
COLUMN B
7. Press: HSillil
L
INJBTEMP
ACTUAL
B
SETPOINT
7,0
14,3
The GC display looks like this.
1.
SETPOINT
The GC display looks like this. The value
shown will be the inlet pressure setting
needed to obtain the flow you entered.
Use the pressure values obtained from this procedure for setting a pressure program. Enter the
initial time, ramp rate, and final time as part of setting the pressure program (see "Setting
Pressure Programs" earlier in this chapter). You will also need to change the oven temperature
if it will change during the pressure program.
Using Electronic Pressure Control 10-31
Setting the Average Linear Velocity
You can use EPC to set the calculated average linear velocity for inlets. For example, when you
set a pressure, the average linear velocity is displayed (while monitoring the average linear
velocity). The following sections will show you how to:
• Understand average linear velocity
• Calculate the outlet flow
• Set the average linear velocity
• Calculate the outlet linear velocity
• Calculate the actual average linear velocity
Understanding Average Linear Velocity
The average linear velocity is calculated and measured at oven temperature, rather than at
ambient temperature. It is an average value because velocity varies continually along the length
of the column (due to the pressure drop and the compressibility of the carrier gas).
To compare experimental values with those displayed by the system, measure the outlet flow
and compare it to the calculated outlet flow. Then measure the average linear velocity and
compare it to the velocity displayed. You need to consider the corrections for both temperature
and compressibility if you use the average linear velocity (unretained peak time) measurements
to calculate flow. You can calculate an approximate value for flow without correcting for
compressibility, but it may differ significantly from the flow value displayed by the system as the
pressure drop increases. A more detailed discussion of these calculations and pressure versus
flow relationships is given in appendix A, "Pressure versus Flow Relationships for Inlet and
Auxiliary Electronic Pressure Control."
Using Electronic Pressure Control 10-32
Calculating Outlet Flow
Outlet flow is the gas flow out of the column. It is measured in ml/min and corresponds to the
measurements made with a flow meter at the detector outlet. The gas is measured at ambient
conditions; however, the outlet flow displayed is calculated using 25 °C and 1 atmosphere
pressure (14.7 psi) as reference conditions.
All flow calculations are based on the ideal gas law.
Ideal Gas Law
PV = nRT
where
T = temperature in K
P = absolute pressure
Setting the Average Linear Velocity
Use the following steps to set the approximate column B average linear velocity to 100 cm/sec.
1. Enter the correct gas type, column diameter, and column length. For more information on
setting the correct column parameters, see the appropriate sections earlier in this chapter.
2. Use the following steps to set the column B average linear velocity to 100 cm/sec:
a. Press: 1CLEAR > .
b. Continue to press: t FL0W ) until you see the average linear velocity display.
ACTUAL
COLUMN B
97.5
SETPOINT
Cm/SeC |
The GC display looks like this.
The value displayed (97.5 cm/sec) is the computed average linear velocity (u) for the
correct pressure, temperature, and gas type.
c. Press: I
1
> I ° I
I ° > I ENTER 1 •
Sets inlet B linear velocity to 100 cm/sec.
Note: Inlet B pressure will change to a value needed to produce 100 cm/sec at the current
oven temperature. Inlet B flow also corresponds to that pressure.
Using Electronic Pressure Control 10-33
Determining the Corrected Column Length
Packed Column Considerations
• Calculations for the pressure versus flow relationship with EPC apply to flow through open
tubular columns.
Measure flow versus pressure to determine the relationship for a packed column and to
check for changes as a column is used.
•
Operating pressure may reach the 100 psi limit for longer columns or higher temperatures.
• EPC offers many advantages over mass flow controllers, including:
- Precision and reproducibility of setpoints
- Rapid adjustment to change in settings during downstream operation
- Pressure programming capability for reduced run times
To set or display the mass column flow for a packed column, you must first calculate the
corrected column length and diameter for an equivalent open tubular column.
Capillary Column Considerations
Although column specifications show the nominal length of the column, not all columns are
manufactured exactly to the nominal specifications. Also, previously used columns are shorter
than their specifications if the ends were cut off to remove contaminants.
To compensate for both packed and capillary column considerations, use the following
procedure to determine the corrected column length and diameter.
Using Electronic Pressure Control 10-34
Note: Before setting the mass flow rate, enter the correct gas type, column diameter, and
column length. For more information on setting the correct column parameters, see the
appropriate sections earlier in this chapter.
1. Use the following steps to set the column B average linear velocity:
a. Press: t CLEAR I .
b. Press:
(FLOW)
repeatedly until the display reads:
ACTUAL
COLUMN B
07.S
SETPOINT
Cm/Sec
The value displayed (97.5 cm/sec) is the computed average linear velocity (u) for the
estimated length (10 M) column.
2. Inject an unretained component into the GC and determine its retention time in minutes.
This is t o Actual in the following equation.
3. Use the following formula to calculate the corrected column length:
T
L corrected
L corrected
0
Actual
(
. t o Actual X
= f =
u
\
,
1
where:
corrected column length in meters
= retention time of unretained component in minutes
u
= average linear velocity in cm/sec
1.67
= (cm to M) 60 min corrections
4. Press: t:i$83;il 1 FLOW l to access the flow parameters display.
5. Continue to press: t FL0W 1 until you see the column length display.
ACTUAL
B:
Column LOO XX.XXM
SETPOINT
The GC display looks like this.
6. Enter the value calculated from the above formula as the corrected column length.
You can check the flow through the column by turning off the detector gases and measuring
the flow using a bubble flow meter and the GC stopwatch feature. See chapter 4, "Using the
Internal Stopwatch" for more details.
Using Electronic Pressure Control 10-35
Optimizing Splitless Injection Using
Electronic Pressure Control
The inlet carrier gas pressure at the time of injection can affect the transfer of sample to the
column dramatically. With low inlet carrier gas pressure, the column flow rate is slower so the
sample stays in the inlet longer. Because of this, the sample has more time to expand. In
addition, low inlet carrier gas pressure results in lower inlet pressure and a larger sample
expansion volume. Conversely, higher flows (or higher pressures) at the time of injection cause
the sample to be swept into the column more rapidly, thus reducing the expansion volume.
Because the inlet pressure can be programmed up or down, it is possible to initiate a run
with a high flow rate and then program the flow downward to a value that is optimal for the
chromatographic separation.
Splitless injection volumes are usually limited to 1 to 2 [xl of sample, but this is highly
dependent upon factors such as the inlet temperature, column flow rate, solvent molecular
weight, solvent boiling point, liner volume, column type, and retention gap use. With
larger injections, poor sample transfer can result in sample losses and molecular weight
discrimination.
A slightly modified pressure programming technique is appropriate for GC-MS systems.
The program starts at a low initial pressure, then ramps up at the beginning of the GC run, and
ramps down again after the sample has been transferred to the column.
An example of rapid pressure programming for a GC-MS system is shown on the following
page.
Using Electronic Pressure Control 10-36
Example Setpoints of Rapid Pressure Programming
Rapid Pressure Program
GC-MS
Constant Flow
Constant Pressure
Init Pres
Init Time
Rate
Final Pres
Final Time
Rate A
Final Pres A
Final Time
10
0
99
40
0.25
99
10
0
Rate
Init
Pres
Init
Time
Single-Ramp Oven Temperature Program
Final
Value.
Init Value
Init Time
Rate
Final Value
Final Time
100
2
10
200
1
Run Time
Using Electronic Pressure Control 10-37
Operating the Gas Saver Application for the
Split/Splitless Inlet
What Is the Gas Saver Application?
The gas saver application is one use of the auxiliary EPC system. It allows you to control
the split vent flow of a split/splitless inlet by controlling supply pressure to the inlet. By
controlling the pressure, you can reduce the total flow rate during nonproductive run times and
laboratory off-hours, which will reduce your GC operating costs. The gas saver is particularly
beneficial for users of expensive carrier gas and for capillary inlet systems used with high split
flows. When properly programmed for a capillary inlet system, constant column head pressure
and column flow rate are maintained while the excess split flow is reduced.
What Are the Required Settings for Operation?
When you operate the gas saver, you must set the auxiliary pressure at least 5 to 10 psi greater
than the inlet head pressure to ensure that column pressure and flow are maintained. To
determine the minimum auxiliary setting, detect the maximum pressure of the programmed run
and add 5 to 10 psi. If you are not using constant flow mode, the column pressure drop
increases and the column flow decreases. If you are using constant flow mode, the pressure will
increase during temperature programming. In general, the operating constraints for the gas
saver application are as follows:
• Operate at least 5 to 10 psi above column head pressure (some minimal split vent flow is
required).
• Operate at least 10 psi above the supply line pressure (or as maintained by the system).
• Use the GC displays and warnings when configuring.
Using Electronic Pressure Control 10-38
How Is the Gas Saver Application Configured?
Split Splitless Inlet,
Back-Pressure Reguialion with EPC
Auxiliary EPC Module
Pressure
Transducer
To EPC Board,
Channel C
r-i-n
Flow
FilterRestrictor
m
Supply
Gas Flow
I
I
i
i
Electronic
Pressure
Control
I
I
Split/
Splitless Inlet
Septum
Purge Line
i
Septum Purge
Regulator
a!
i
Pressure Mass Flow
Transducer Controller
Septum
Purge Vent
To EPC
Board,
Channel
AorB
Valve
To Detector
Electronic
Pressure
Control
Valve
Using Electronic Pressure Control 10-39
How Does the Gas Saver Application Operate?
When an EPC module is used for gas supply to the split/splitless inlet (gas saver
configuration), restriction is due mainly to the mass flow controller. You can vary the
restriction by changing the setting of the mass flow controller.
To operate in gas saver mode, you need to enter the gas type, column length, column diameter,
column pressure, and split flow rate. You will also need to calibrate the flow versus the
pressure, set the mass flow controller to the desired range, and determine the column head
pressure. Be sure that all the hardware is installed properly and that all gases are plumbed.
Use this procedure to determine the settings that will yield the most gas savings for your
system:
Zero the Channel
1. Check your system for leaks.
2. Zero your channel if ambient conditions have changed significantly:
a. Make sure that all heated zones are cool.
b. Set the auxiliary and inlet pressures to zero.
c. Remove the septum nut to depressurize the system completely. The example below
shows the display for auxiliary EPC channel C.
Note: Setting the inlet pressure to 0.0 may noty depressurize the channel completel. You
may also need to bleed off at the 1/8-in Swagelok fitting.
Sets the channel C pressure to 0.0.
d. Press:
1PCC:
ACTUAL
SETPOINT
10.0
0.0
The GC display looks like this.
where 10 is the zero offset value labeled "actual" on the GC display.
Using Electronic Pressure Control 10-40
Enter the Carrier Gas Pressure
1. Enter the carrier gas supply pressure at the keyboard. A typical pressure is 50 to 60 psi.
For example:
a. Press:
EW&**
1A 1 I
5
1 1 ° 1 1ENTER 1
ACTUAL
SETPOINT
50.0
50.0
Sets the channel C pressure to 50.0.
The GC display looks like this.
2. Turn the mass flow controller on the front of the flow panels until you measure
80 to 100 ml/min (or the desired flow) with the bubble flow meter.
Note: You must wait 1 to 2 minutes after changing pressure or mass flow controller settings
to allow the system to stabilize before measuring flows or making an injection.
Enter the Column Parameters
1. At the keyboard, press: i&%@iill [ FLOW | to access the flow parameters table.
2. Press: [ FL0W 1 to scroll through the table. Enter your values for the following:
• Constant flow (on or off)
• Gas type
• Vacuum compensation (on or off)
• Column diameter
• Column length
• Split flow
For more information on setting these parameters, see the appropriate sections earlier in
this chapter.
3. To verify the column flow, measure the flow out of the detector with a bubble flow meter.
Using Electronic Pressure Control 10-41
Set the System to Operating Conditions
Use the flow restrictor tables described in "Setting Pressure Using Auxiliary Electronic Pressure
Control" earlier in this chapter to select the makeup gas pressure that will yield the flow you
need. For example, the following steps describe how to set the pressure to get 30 ml/min
makeup gas flow.
1. Set the inlet pressure to 10 psi (if it is not set already).
2. Set the makeup gas at the keyboard to get to approximately 30 ml/min.
3. Start to heat any heated zones that are not already heated.
WARNING
HEAT THE DETECTOR BEFORE YOU CONTINUE.
4. If you did not select constant flow, verify the flows after the zones reach their desired
temperatures.
5. After the system reaches equilibrium, check and record the final pressure at the maximum
operating temperature.
Note: Record the final pressure so that you know what value to set for the reduced gas saver
pressure, and then observe the pressure at the maximum operating temperature. If you want
a higher temperature than listed in the operating manual, realize what that pressure will be
when you reset it.
Set the System to Off-Hour Conditions
If the final column pressure is 50 psi, set the carrier gas pressure to 65 psi. During off-hours,
you can program the carrier gas down.
1. Program the desired oven temperature.
2. Set all detector and inlet flows and pressures to the desired levels.
3. Set the carrier gas pressure to a value 15 psi higher than the column head pressure.
Using Electronic Pressure Control 10-42
Recommended Flow Rates for Inlet Systems
Using the Gas Saver Application
For a capillary split/splitless injection port, a combined flow rate out of the split vent and the
purge vent of approximately 5 — 10 ml/min is recommended.
Additional Benefits of the Gas Saver Application
If desired, the makeup gas flow can also be reduced using the gas saver mode during off-hours
to increase total gas savings. Plumb the gas saver outlet line into the detector manifold inlet
fitting for makeup gas. Then set it using the same procedure as for a carrier gas.
With a capillary inlet, the gas saver can also be used as a quick, convenient way to set split ratio.
The graphs below show examples:
Split Injection
High Flow just during
Sample Splitting Period
(plus Oven Cooldown Cycle)
I
4
Oven
Cooldown
Period
I
I
I
7
8
5
6
GC Run Time (in Minutes)
1
I
I
1
9
10
11
12
Splitless Injection
150
JE
If
100 - I
DC
o
50
a.
GO
V
10 0
0
1
T
4
T
I
5
6
7
GC Run Time (in Minutes)
Using Electronic Pressure Control 10-43
13
Using the External Sampler Interface
The external sampler interface kit (HP part number 19245-60990) enables you to use EPC with
a sampling device other than a standard HP inlet. The conventional interfacing of external
sampling devices is not possible when EPC inlets are used. The external sampler kit provides
the hardware and diagrams for installing the kit onto forward-pressure controlled inlets
(programmable cool on-column and purged packed). The kit also contains hardware for limited
use of the back pressure-regulated split/splitless inlet. This hardware allows the system to sense
the pressure at a different location inside the HP pneumatic system.
Which Configuration Should I Use?
The external sampler interface is configured differently depending on the type of inlet you use.
You will select one of several typical configurations of the external sampler interface depending
on how you use your inlet. Use the following tables to determine the configuration you need.
The diagrams shown in this section include the most commonly configured systems.
Inlet Use
External Sampler Interface Kit
Auxiliary Module
External Inlet
•
•
HP inlet used as a thermal zone
•
•
HP inlet used for injection
•
Forward-Pressure Regulation
Inlet Use
Front End Sampler for Purged
Packed and On-Column Inlets
Back-Pressure Regulation
Front End Sampler Interface for
Split/Splitless Inlets
External Interface
•
•
HP inlet used for sample
introduction
•
•
HP inlet not used for
sample introduction
•
•
Using Electronic Pressure Control 10-44
External Sampler Interface Configuration Decision Tree
Do you already
have an EPC inlet?
Use Aux
EPC module
See configuration 8
BPR
split/splitless
inlet
ill you use this
inlet for sample
introduction?
Is it an FPR
(purged packed
oron-column)
inlet?
> - No
you use this
inlet for sample
introduction?
See
configuration 6
Is the inlet use
as a thermal zone
only (purge an
trap)?
ill sample be
introduced through
the septum?
No interface
kit needed
See
configuration 7
No
Will sample be
introduced through
the septum?
Sample introduced
through the carrier
line
Sample introduced
through the carrier
line
Yes
See configuration 5
No
See configuration 1
See configuration 3 )
Using Electronic Pressure Control 10-45
Configuration 1: External Sampler Interface to HP Inlet with FPR
Forward-pressure regulation for the septum-purged packed inlet (EPC used with open
tubular columns). External sampler interface (needle through septum) to HP inlet with
forward-pressure control. A static headspace sampler can be interfaced in this way.
EPC
Board
Heated
Interface
Three-
External
Sampler
Pressure
Transducer
A ; Way
Adapter
Fitting
Valve
Carrier
Gas
Flow
Septum Purge Regulator p..!™
y
(with Brass M8 Plug)
Vent
Septum Purge
Electronic
Pressure
Control Valve
New Pressure Sensor
Line to the Transducer
Using Electronic Pressure Control 10-46
External Sampler
Direct to Column
Interface
Flow
Restrictor
Capped
Septa
Purge
(if
required)
Configuration 2: External Sampler Interface to Column or to HP Inlet with FPR
Forward-pressure regulation for the on-column inlet and the septum-purged packed inlet
(EPC used with open tubular columns). To External Sampler direct column interface or to HP
inlet. Use the HP inlet with forward EPC.
Heated
Transfer Line External
Sampler
Pressure
Transducer
Septum Purge
Regulator (with Septum
Brass M8 Plug) Purge Vent
Carrier
Gas
Flow
Direct to
Column
Interface
in Injection
Port Location
Electronic
Pressure
Control Valve
Flow
/N
Restrictor |
Capped
Septa Purge
(if required)
New Pressure Sensor
Line to the Transducer
To Detector
The position of the three-way valve directs the EPC flow to the external sampler or to the HP
inlet. This diagram shows the EPC flow directed to the external device.
Using Electronic Pressure Control 10-47
Configuration 3: EPC to External Sampler to HP Inlet with FPR
Forward-pressure regulation for the on-column inlet and the septum-purged packed inlet (EPC used
with open tubular columns). From HP EPC pneumatics to external sampler and return to HP inlet. This
configuration should not be used with compounds that have a retention index greater than 400-450.
EPC
Board
External
Sampler
L
JZ.
V
Carrier
Gas ~
Flow
~!
Pressure
Transducer
H
Septum Purge Regulator Septum
(with Brass M8 Plug)
Purge Vent
T
Septum Purge
Electronic
Pressure
Control Valve
Using Electronic Pressure Control 10-48
Flow
Restrictor
Capped
Septa
Purge
Configuration 4: EPC to External Sampler
Forward-pressure regulation for the on-column inlet and the septum-purged packed inlet
(EPC used with open-tubular columns). To external sampler only. The HP pneumatics are
used. The HP inlet is not functional.
EPC
Board
Heated
Transfer Line
Inlet not Connected to
pneumatics (blocked with
1/8-in Swagelok caps)
External
Sampler
Pressure
Transducer
Septum Purge
Regulator (with
Brass M8 Plug)
Adapter
Fitting
Direct to
„ .
Column
Carner_
Interface [? a s
in Injection Flow
Port Location
Column
Septum
Purge
Vent
V
Septum
Purge
Electronic
Pressure
Control Valve
Flow
Capped
Restrictor Septa
Purge
(if
required)
New Pressure Sensor
Line to the Transducer
To Detector
Using Electronic Pressure Control 10-49
Configuration 5: Back Pressure Regulated EPC with Inlet
Back-pressure regulation for the split/splitless inlet. The external sampler is placed in the HP
split/splitless capillary inlet flow system (in series). The external sampler transfer line was interfaced (cutting 1/16-in. od tubing is required) close to inlet carrier in line. Septa purge is
capped to prevent sample losses. The pressure sensing takes place just before the EPC valve.
Pressure
Transducer
External
Sampler
Heated
transfer line
L
Septum Purge
Regulator (capped)
Split/Splitless Inlet
Carrier
Flow
Septum
Restrictor Purge
Vent
Solenoid Valve (capped) I -
Gas
Flow
Mass Flow
Controller
External Sampler placed in
Series with HP Split/Splitless
capillary inlet. A static
headspace sampler would
interface to an EPC split inlet
in this way.
Electronic
Pressure
Control
Valve
V
To Detector
Using Electronic Pressure Control 10-50
Split
Vent
M8 x M8 union
with Post Drawn
Weldment Tube for
Pressure Sensing
Configuration 6: Back Pressure Regulated EPC with No Inlet
Back-pressure regulation for the spliVsplitless inlet. External sampler using the HP inlet
back-pressure regulation of column. HP inlet not used. The external sampler has its
own direct column interface in the unused inlet opening.
**
Pressure
Transducer
T
Split/Splitless Inlet
Septum Purge
septum Purge
Regulator (capped) vent (capped)
Septum Purge Line I
"
Carrier
Gas
Flow
External S a m p l e r ^
Direct Column
Interface
Column
Electronic
Pressure
Control
Valve
Split
Vent
M8 x M8 union
with Post Drawn
Weldment Tube for
Pressure Sensing
\
To Detector
Using Electronic Pressure Control 10-51
Configuration 7: Forward Pressure Regulated EPC with Inlet as Thermal Zone
Forward-pressure regulation for the septum-purged packed inlet (EPC used with
open tubular columns). External sampler interface direct to column with HP inlet forward
EPC. HP inlet used only as heated transfer and support of direct column interface device.
1
Pressure
Transducer
Septum Purge Regulator
(with Brass M8 Plug)
Vent
Carrier
Gas
Flow
Septum Purge
External Sampler
direct to column
interface
Electronic
Pressure
Control Valve
Column
New Pressure Sensor
Line to the Transducer
Y
To Detector
Using Electronic Pressure Control 10-52
]H
Flow
Restrictor
Capped
Septa
Purge
(if
required)
Configuration 8: EPC with Auxiliary EPC Module
Aux EPC Module
(as Carrier Source)
Sampling Device
HP 5890 GC
For more information on using auxiliary EPC, see the headspace configuration in "Using Valve
Options" later in this chapter. For further information, see "Applications of Auxiliary
Electronic Pressure Control in Gas Chromatography," HP application note 228-202, HP
publication number (43) 5091-5013E.
Using Electronic Pressure Control 10-53
Using the External Sampler Interface with an Inlet as a Heated Zone
The external sampler device introduces a slight pressure drop over the system. To compensate
for this pressure drop, measure the actual flow with a bubble flow meter to determine the
additional pressure necessary during the run. For example, measure the flow at the column
outlet, or use an unretained peak to determine the average linear velocity. The pressure setting
will probably be somewhat higher than would be used by the column alone.
Special Considerations
If you are using an HP 19395A headspace sampler with a needle interface to the inlet, replace
the septum nut with the black septum nut with the wide aperture before using it.
For easier access to the external sampler interface, try to place the three-way flow diverter
valve so it is reached easily through the side door of the GC.
Some devices go into a timed desorbtion cycle that increases the pressure drop through the
system, consequently reducing the flow rates. To compensate for the increased pressure drop,
program a pressure ramp at the beginning of the start cycle. For example, ramp the pressure
from 16 psi to 35 psi at 99 psi/min. Then program the pressure down to 16 psi for the duration
of the analysis.
Whenever an external device is placed in series with an EPC inlet system, some of the direct
flow displays will be incorrect because we do not know what the total pressure drops are
relative to just the column (such as column id and length). In this case, ignore the display and
measure the actual flows. If the external device switched valves, multiple columns, or traps
during a run, then the flows may also change. You may want to compensate for these situations
in your pressure programs.
Using Electronic Pressure Control 10-54
The standard forward-pressure configuration is shown below.
Forward-Pressure Regulation for the On-Column Inlet and the
Septum-Purged Packed Inlel (EPC Used with Open-Tubular Columns)
EPC
Board
Programmable Cool
On-Column Inlet
Pressure
Transducer
H
Carrier
Gas "
Flow
Septum Purge
Regulator
Septum
Purge
Vent
Septum Purge
Flow
Restrictor
Electronic Pressure
Control Valve
Column
To Detector
Using Electronic Pressure Control 10-55
The standard back-pressure configuration is shown below.
Back-Pressure Regulation for the Split/Splitless Inlet
Pressure
Transducer
Septum
Purge
Regulator
Split/Splitless Inlet
•—,
Carrier
Gas Flow
L j — [ } Septum Purge Line
Mass Flow
Controller
Split Line
Flow
Restrictor
Solenoid Valve
Column
\|/
To Detector
Electronic
Pressure
Control
Valve
Split
Vent
Using Electronic Pressure Control 10-56
I
I
Septum |
Purge
Vent
I- EPC
Board
Using Valve Options
The valve options described in this section demonstrate several applications of the auxiliary
EPC system. Hewlett-Packard supplies 17 standard plumbing configurations for the HP 5890.
These configurations may be ordered through the HP 18900F Valve Ordering Guide,
HP part number 5091-4240E.
This section describes advanced auxiliary EPC valving applications that will require some
method development time from the user. In general, all HP valves are compatible with auxiliary
EPC. However, some valve options may require additional method development time. For
some configurations, such as a packed-column refinery gas analyzer that operates isothermally,
an auxiliary EPC module can be used in constant pressure mode as easily as the standard
mechanical pneumatics. With packed-column valve applications, be sure to check the flows with
a bubble flow meter every time you change the system pressure.
If you run your system only in constant flow or constant pressure mode, without pressure
programs, then an auxiliary EPC module may be just as effective as a manual flow controller for
your applications. However, most operations become easier to automate once you are using
EPC. In fact, EPC should give faster response to changes in the back pressure of the column
and better repeatability of known retention times. When constant flow mode is used with
packed columns, actual flow may increase or decrease with temperature programming. It is best
to calibrate the flow at the initial and final oven temperatures, and then use a two-point
calibration with pressure programming.
The following diagram shows a common 10-port valve configuration plumbed with an EPC
split/splitless inlet and one general-purpose auxiliary EPC module. This configuration is used
for the analysis of oxygenates in gasoline.
Using Electronic Pressure Control 10-57
10-Porl Valve Configuration wilh Two Channels of EPC
56-cm Micropacked TCEP
Carrier
Gas Flow
•lA—
Mass Flow
Controller
flOOflflOOB
Split/Splitless
Inlet with EPC
30 m x 0.53 mm x 2.6 m HP-1
Channel A
S2
Supply
Gas Flow
Aux
EPC
Module
Channel C
"
Adjustable
Restrictor
Vent
Using Electronic Pressure Control 10-58
Headspace Sampling Systems Product
Vent
Carrier
Gas Flow
Aux
EPC
Module
r^
S2
Supply
Gas Flow
S1
Aux
EPC
Module
Sample
Loop
Needle
toGC
Headspace Vial
EPC can be applied to headspace sampling. The six-port valve configuration in the figure above
shows the application of two general-purpose auxiliary EPC modules. One module is used for
carrier gas flow, and the other module is used for precise vial pressurization.
Using Electronic Pressure Control 10-59
Which Valves Work Best with Auxiliary Electronic Pressure Control?
Almost all HP valves are compatible with auxiliary EPC, and many of the standard
configurations offer additional system benefits. For example, using valve options for specific
applications can help you maintain better reproducibility, reduce ambient temperature
sensitivity, and rapidly change the flow rate. Using valves with auxiliary EPC also contributes to
easier setup and simplified automation. In addition, auxiliary EPC valves make it easier to
change run times and to reduce analysis time.
Valve configurations such as Options 205 and 401 can also be used with EPC. If pressure
programming is used, you may need to change the pressure program whenever you change the
valve timing. Failing to change the pressure program will produce incorrect results.
Precolumn
1st
Carrier
(EPC)
2nd
Carrier
(EPC)
Column
Detector
OFF
ON
Options 205 and 235 backflush precolumn
Using Electronic Pressure Control 10-60
A common application has Option 401 interfaced to a capillary Split inlet. The system uses an
EPC Split/Splitless inlet (main carrier) and one general-purpose auxiliary EPC module for
control of the second carrier source. The interface between the capillary inlet and the valve is
Option 901.
Split/Splitless EPC Injection Port B
Split Vent
Capillary
Column 2
Detector
2
Packed
Precolumn
Injection
PortB
Carrier
Sample
In
Sample
Out
Aux Carrier
(Aux EPC)
OFF
Valve 1
Option 401. Detector 1—FID, Detector 2—TCD
Using Electronic Pressure Control 10-61
A
Appendix
Pressure versus Flow Relationships for Inlet and Auxiliary
Electronic Pressure Control
While pressure is the parameter controlled and measured with the EPC system, the
corresponding column outlet flow rate and average linear velocity are also calculated and
displayed on the keypad. Entries can also be made in terms of either flow or velocity, from
which the system calculates the required pressure and enters this setpoint.
It is important to understand how pressure, flow, and linear velocity are related so that the
displayed values can be compared with each other and with the correct experimental measurements. This section includes a summary of some of the basic equations for flow through open
tubular columns and the calculations that are carried out by the HP 5890 Series II GC and
HP 3365 ChemStation systems. Some of the terms and units used throughout this section are
shown below.
Terms and Units Used in This Section
F
Column outlet flow, ml/min
V
Average linear velocity, cm/sec
L
Column length, cm
r
Column inner radius, cm
t
Retention time, seconds
T
Column (oven) temperature, K (°C + 273)
11
Carrier gas viscosity at temperature T, poise
Pi
Inlet pressure, absolute
Po
Outlet pressure, absolute; zero if vacuum compensation specified
Tref
Reference temperature; 25 °C = 298 K
Pref
Reference pressure; 1 atm = 14.7 psi = 1.01325 x 106 dynes/cm2
T re f/T
298/323 = 0.923
Column
25 m x 0.32 mm, Helium carrier
Appendix A-1
Outlet Flow
Column outlet flow can be calculated from Equation 1:
6(kr 4
F=
16T)L
r Tref "i r Pi2 - Po 2 i
L T J L p«f J
Since the gas volume depends on both temperature and pressure, it is expressed here under
reference conditions, Tref and Pref. Flows displayed by the 5890 are based on reference
conditions of 25 °C and 1 atmosphere pressure, for comparison with experimental values
measured under ambient conditions with a flow meter at the outlet of the detector.
Average Linear Velocity
Flow cannot always be measured directly at the detector outlet, as in work with a mass
spectrometer or at very low flow rates. An alternative is to measure the elution time for an
unretained peak and calculate the average linear velocity for gas flowing through the column.
This value is determined at oven temperature T.
E
v=-L-
12
t
The average linear velocity can also be calculated from pressure, temperature, and column
parameters according to Equation 3, as was done for outlet flow using Equation 1.
(Temperature does not appear separately, but is included in the viscosity term in this equation.)
- _
3r2
32TIL
(Pj2 - PQ 2 ) 2
(Pj
3
-
3
Po )
This is the calculation used for the velocity value displayed by the HP 5890. It is calculated at
oven temperature, corresponding with experimental measurements from elution time of an
unretained peak (equation 2).
Appendix A-2
Eq3
Calculating Flow from Average Linear Velocity
Combining equations 1 and 3 gives an equation that can be used to calculate flow from average
linear velocity.
Eq4
3Pref "
=
"~
Terms for both temperature and pressure appear in this equation. The ratio T re /T corrects for
the difference in temperature (ambient versus oven) at which flow and velocity were calculated.
The pressure term is related to effects of the gradient from inlet to outlet pressure. Because the
carrier gas is compressible, linear velocity varies along the length of the column, depending on
the pressure at each point. Retention time measurements reflect the average linear velocity v,
but the pressure-gradient term must be included to calculate flow at the outlet.
Column flow is often approximated from measurements of unretained peak time according to
equation 5, without including these corrections (see chapter 4, "Setting Inlet System Flow
Rates" earlier in this manual).
F s 60nr\
Eq 5
This can be a good approximation, when the pressure drop is small and temperature is near
Tref. The compressibility correction becomes increasingly important as the pressure drop
increases, however, and flow values approximated using equation 5 may differ significantly
from those calculated by the system according to equation 4.
The examples below show how the two flow calculations compare for one column under
different sets of operating conditions. In these examples, temperature has been held constant
to illustrate the effect of changes in the compressibility factor. It can be seen from the
equations, however, that changes in the temperature ratio will also affect the overall result and
comparison between calculations.
Appendix A-3
Keyboard Displays
Example
Inlet Pressure
Flow (ml/min)
Velocity (cm/sec)
1
4.6 psig (19.3 psia)
1.00
19.3
2
8.3 psig (23.0 psia)
2.00
34.5
3
14.3 psig (29.0 psia)
4.00
58.4
Example 1—Inlet Pressure 4.6 psig
1. Calculating flow from the average linear velocity using equation 4:
F = 60 (3.14) (0.016)2 (0.923)
3 (14.7)
(19.3)3 - (14.7)3"] v
(19.3)2 - (14.7)2J
F = (0.0482) (0.923) [1.164] (19.3) = 1.00
2. Calculating flow from the average linear velocity using the approximation in Equation 5:
F a 60(3.14)(0.016)2v
F . (0.0482) (19.3) = 0.93
Example 2—Inlet Pressure 8.3 psig
1. Calculating flow from the average linear velocity using Equation 4:
2
F = 60 (3.14) (0.016)
(0.923)
[•
^ - (14.7)
.7) 331I v
2
.O)2 - (14.7)
.7) ]
F = (0.0482) (0.923) [13.03] (34.5) = 2.00
2. Calculating flow from the average linear velocity using the approximation in Equation 5:
Fa 60(3.14)(0.016)2~v
F e (0.0482) (34.5) = 1.66
Appendix A-4
Example 3—Inlet Pressure 14.3 psig
1. Calculating flow from the average linear velocity using equation 4:
f
F= 60 (3.14) (0.016)2
2
(0.923)^___
(29.0) 3 - (14.7)31 v
(290)2_(147)2j
F = (0.0482) (0.923) [1.540] (58.4) = 4.00
2. Calculating flow from the average linear velocity using the approximation in equation 5:
F* 60 (3.14) (0.0 16)2 v
F m (0.0482) (58.4) = 2.82
References
More detailed discussions on pressure versus flow relationships in capillary GC can be found in
many general references; two are listed here.
I
,•
1. W.E. Harris and H.W. Habgood, Programmed Temperature Gas Chromatography, Wiley, New
York, 1966.
2. J.C. Giddings, Unified Separation Science, Wiley, New York, 1991.
Appendix A-5
Index
Adapters, bubble flow meter, 4-4
Assigning a signal, 6-2
Attenuation
on/off, output signals, 6-12
output signals, 6-9
Auxiliary zones
suggested pressure ranges, 10-17
temperature control, 3-15
with EPC, 10-2
Average linear velocity, 10-32,10-33, A-2
B
Bead
conditioning, 5-44
contamination, 5-53
power setting, 5-45
preserving lifetime, 5-54
Bubble flow meter, 4-2
adapters, 4-4
Capillary columns
corrected length, 10-34
flows for FID, 5-21
flows for NPD, 5-49
flows for TCD, 5-31
flows with ECD, 5-63
flows with FPD, 5-71
installation in ECD, 2-28
installation in FID, 2-20
installation in FPD, 2-32
installation in NPD, 2-20
installation in packed inlets, 2-12
installation in split/splitless inlets, 2-14
installation in TCD, 2-24
preparation, 2-2
Capillary inlet
flows, 4-9
flows in split mode, 4-11
flows in splitless mode, 4-18
Carrier gas, for TCD, 5-33
Carrier gases, type, 4-25
Column
corrected length, 10-34
diameter, 10-26,10-41
length, 10-26,10-41
Column compensation
assigning data, 5-40, 7-12
displaying status, 5-37
making a compensation run, 5-38
message displays, 5-39
single, 5-36
starting a run, 7-10
status display, 7-9
Column installation, 2-1
1/4 in. metal in FID, 2-16
1/4 in. metal in NPD, 2-16
1/8 in. in FID, 2-18
1/8 in. in NPD, 2-18
1/8 in. metal in FPD, 2-30
1/8 in. metal in TCD, 2-22
capillary in capillary inlets, 2-14
capillary in ECD, 2-28
capillary in FID, 2-20
capillary in FPD, 2-32
capillary in NPD, 2-20
capillary in packed inlets, 2-12
capillary in TCD, 2-24
capillary inserts, 2-4
glass columns in ECD, 2-26
glass columns in packed inlet, 2-10
metal columns, 2-8
Column preparation
capillary columns, 2-2
metal columns, 2-6
Compensation, single column, 5-36, 7Constant flow, inlets, 10-28
Cryogenic oven control, 3-6
Daily shutdown, 1-2
Daily startup, 1-2
Detectors
ECD, 5-56
FID, 5-16
FPD, 5-68
NPD, 5-42
TCD, 5-29
nitrogen-phosphorus, 5-42
pressure control, 10-14
pressure programming, 10-15
status, 5-2
temperature control, 3-13, 3-15
temperature display, 3-13
with EPC, 10-2
Display, output signals, 6-5
ECD—Electron Capture Detector
contamination, 5-66
flow rates, 5-60
flows for packed columns, 5-62
flows with capillary columns, 5-63
gases, 5-59
installing capillary columns, 2-28
installing glass columns, 2-26
leak testing, 5-67
operation, 5-56
pressure control, 5-64
radioactive leaks, 5-67
selecting gases, 5-61
temperature effects, 5-59
U.S. owners, 5-57
Electronic pressure control
EPC—Electronic Pressure Control, 10-1
and valves, 10-60
auxiliary pressure control, 10-12
auxiliary zones, 10-2
auxiliary, suggested ranges, 10-17
constant flow mode, 10-8
detectors, 10-2
FID, 5-24
FID makeup gas, 5-27
flow and pressure relationships, A-l
inlets, 10-2
mass flow rate, 10-29
optimizing splitless injection, 10-36
programming inlet flow, 10-30
safety shutdown, 10-4
vacuum compensation mode, 10-27
Equilibration time, 3-5
External sampler interface, 10-44, 10-54
FID—Flame Ionization Detector
flows for capillary columns, 5-21
gas flows, 5-19
installing capillary columns, 2-20
installing metal columns, 2-16, 2-18
lighting flame, 5-28
makeup gas control, 5-26
on/off control, 5-27
operation, 5-16
optimizing, 5-16
How control
EPC, 10-22
inlet programming, 10-30
Flow ranges, packed inlet, 4-5
Flow rates
bubble meter, 4-2
display, 4-25
measuring, 4-1
outlet, 10-33, A-2
recommended for gas saver, 10-43
Flows
capillary columns with ECD, 5-63
capillary columns with FID, 5-21
capillary columns with FPD, 5-71
capillary inlet, 4-9
capillary split mode, 4-11
capillary splitless mode, 4-18
displays, 10-24
ECD, 5-60
ECD with packed columns, 5-62
EPC constant flow mode, 10-8
FID, 5-19
NPD with capillary columns, 5-49
NPD with packed columns, 5-47
packed columns with FPD, 5-69
stopwatch, 4-27
FPD—Flame Photometric Detector
flows for packed columns, 5-69
flows with capillary columns, 5-71
installing capillary columns, 2-32
installing metal columns, 2-30
lighting the flame, 5-74
on/off control, 5-74
operation, 5-68
pressure control, 5-72
Glass columns
installation in ECD, 2-26
installation in packed inlets, 2-10
H
Heated zones
actual, 3-2
detector temperatures, 3-13
inlet temperatures, 3-13
setpoints, 3-2
I
INET, 6-14, 7-14
start/stop a run, 7-1
Inlet flow control, 4-1
Inlets
constant flow, 10-28
flow rates for gas saver, 10-43
gas saver and capillary inlet, 10-38
mass flow rate, 10-29
pressure control with EPC, 10-6
pressure programming, 10-9
programming flow, 10-30
temperature control, 3-13, 3-15
temperature display, 3-13
with EPC, 10-2
Inserts, split/splitless inlet, 2-4
Installation, checklist, 1-1
Installing columns, 2-1
Gas flows, FID, 5-19
Gas saver
operation, 10-38
recommended flows, 10-43
zeroing, 10-40
Gas selection, ECD, 5-61
Gas type, 10-25
Gases, ECD, 5-59
Leak test, ECD, 5-67
Leak testing, ECD, radioactive, 5-67
LED, status indicators, 7-2
Lightening the flame, FPD, 5-74
Loading setpoints, 8-1, 8-2
M
Makeup gas, FID, 5-26
Making a run, 7-1
Mass flow rate, 10-29
Metal columns
installation in FID, 2-16, 2-18
installation in FPD, 2-30
installation in NPD, 2-16, 2-18
installation in packed inlets, 2-8
preparation, 2-6
Output signals
andlNET, 6-14
as timed events, 7-20
assigning, 6-2
attenuation, 6-9
attenuation on/off, 6-12
display or monitor, 6-5
on/off control, 6-8
zeroing, 6-7
Oven
cryogenic operation, 3-6
temperature control, 3-4
temperature control and display, 3-4
temperature programming, 3-8
N
NPD—Nitrogen-Phosphorus Detector
bead lifetime, 5-54
bead power, 5-45
conditioning the bead, 5-44
contamination, 5-53
flows for capillary columns, 5-49
flows for packed columns, 5-47
installing capillary columns, 2-20
installing metal columns, 2-16, 2-18
on/off control, 5-52
operation, 5-42
optimizing, 5-53
On/off control
FID, 5-27
FPD, 5-74
NPD, 5-52
signal attenuation, 6-12
signals, 6-8
TCD, 5-35
valves, 7-18, 9-2
Optimizing
NPD, 5-53
splitless injection, 10-36
Outlet flow, 10-33, A-2
Packed columns
corrected length, 10-34
ECD flows, 5-62
flows for NPD, 5-47
flows for TCD, 5-30
flows with FPD, 5-69
gas flows for FID, 5-19
Packed inlet
flow ranges, 4-5
installing capillary inlets, 2-12
installing glass columns, 2-10
installing metal columns, 2-8
septum purge, 4-6
Polarity inversion, TCD, 5-35, 6-12
Pressure control
auxiliary EPC, 10-12
capillary columns with FPD, 5-72
detector programming, 10-15
detectors, 10-14
ECD, 5-64
EPC, zeroing, 10-6
for FID, 5-24
for FID makeup gas, 5-26
for TCD, 5-32
inlet programming, 10-9
inlets with EPC, 10-6
NPD with capillary columns, 5-50
restrictors, 10-17
Programming
checking inlet pressures, 10-11
detector pressure, 10-15
inlet flow, 10-30
inlet pressure, 10-9
oven temperature, 3-8
Restrictors, 10-17
Run
making, 7-1
start/stop, 7-1
start/stop using INET, 7-1
Safety shutdown, 10-4
Sensitivity, TCD, 5-34, 7-22
Septum purge, 4-6
Setpoints
loading, 8-1, 8-2
storing, 8-1
Shutdown, instrument, 1-2
Signal output, 6-1
Signals
and INET, 6-14
as timed events, 7-20
assigning, 6-2
attenuation, 6-9
attenuation on/off, 6-12
display or monitor, 6-5
on/off control, 6-8
zeroing, 6-7
Single column compensation, 5-36, 7-8
Split mode, flows in capillary inlet, 4-11
Split/splitless inlet
gas saver, 10-38
inserts, 2-4
installing capillary columns, 2-14
Splitless injection, optimizing, 10-36
Splitless mode, flows in capillary inlet, 4-18
Start/stop control, run, 7-1
Startup, instrument, 1-2
Status
column compensation, 7-9
LEDs, 7-2
valves, 9-1
Stopwatch, 4-27, 7-6
Storing setpoints, 8-1
TCD—Thermal Conductivity Detector
carrier gas type, 5-33
changing sensitivity, 7-22
flows for capillary columns, 5-31
flows for packed columns, 5-30
installing capillary columns, 2-24
installing metal columns, 2-22
on/off control, 5-35
operation, 5-29
polarity inversion, 5-35, 6-12
pressure control of flow, 5-32
setting sensitivity, 5-34
Temperature, effects on ECD, 5-59
Temperature control
auxiliary zones, 3-15
detectors, 3-15
heated zones, 3-1
oven, 3-4
Temperature limits, 3-3
Temperature programming, oven, 3-8
Time key, 7-6
Timetable
creating an event, 7-17
events, 7-15
modifying events, 7-23
switching signals, 7-20
valve control, 9-3
during a run, 7-18
on/off control, 7-18, 9-2
options, 10-57
w
WARN:OVEN SHUT OFF, 3-6
Wipe test, ECD, 5-67
Vacuum compensation, 10-27
Valve, status, 9-1
Valve box, 3-16
Valves
and EPC, 10-60
controlling, 9-1
Zeroing
EPC pressure, 10-6
gas saver, 10-40
output signals, 6-7
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