Calibration book 12-2012
Foxcroft Equipment & Service, Co. Inc.
The Calibration Book
For detector models: FX-1, FX-1500, FX-1502, FX-1504 and FX-2
Warning!
Please Read Carefully and Save.
Copyright © 2012 FOXCROFT
Every effort has been made to ensure the accuracy of this document at the time of printing. In accordance with the
company’s policy of continuous product improvement, Foxcroft reserves the right to make product changes without notice.
No liability is accepted for any consequential losses, injury or damage resulting from the use of this document or from any
omissions or errors herein.
Table of Contents
Important Safety Information 3
Introduction 4
1 CALIBRATION 5
2 SHORT GAS LEAK TEST 9
3 FULL SENSOR CALIBRATION 10
4 FX EASY CALIBRATION 13
5 GAS SENSOR REPLACEMENT 17
6. PARTS LISTING 19
9
MONTHLY SENSOR TEST LOG
20
10 WEEKLY ELECTRONIC TEST LOG 21
7
SERVICE 23
11 PRODUCT WARRANTY 25
2
IMPORTANT SAFETY INFORMATION
Please read and observe the following:
All functions of this gas detection system
must be verified on a regular basis.
WARNING: Target calibration gas contains toxic gas and should
only be used by personnel who are fully trained in gas calibration
procedures. All safety procedures and warnings on the gas bottle
should be read, understood, and observed.
HELPFUL IDENTIFIERS
In addition to information on installation and operation, this instruction manual may contain WARNINGS
pertaining to user safety, CAUTIONS regarding possible instrument malfunction, and NOTES on
important, useful operating guidelines.
WARNING: A warning looks like this. It warns you of the potential for personal
injury
CAUTION: A caution looks like this. It alerts you to the possibility of instrument
malfunction or damage.
NOTE: A note looks like this. It alerts you to important operating information.
3
Introduction
All functions of gas detection systems must be checked and verified on a
regular basis.
Important: All trimmers required in the calibration procedures are in the Gas Sensor Enclosure.
Please take a few minutes to review the logistics of trimmers.
WARNING: Do not attempt to calibrate any trimmers in the Remote Alarm
Unit. These trimmers are factory set.
4
Calibration
Regulator
Gas Cylinder
Tubing
Calibration Nose
Figure 1
5
The Calibration Book
Calibration
Important: To calibrate the gas sensor a certified target calibration kit is required. The Calibration Gas
Kit includes one target gas cylinder, regulator, tubing and certification sheet. A separate calibration kit
is required for each type of gas you monitor.
Tools required:
•
•
•
•
Jeweler’s Screwdrivers (full calibration only)
Calibration nose with O-Ring and caps (Provided with all gas sensors)
Calibration Gas Kit (pictured below)
Digital Voltmeter (full calibration only, optional)
Tubing
Regulator
Gas Cylinder
Calibration Nose
Figure 2
6
The Calibration Book
Calibration
WARNING: Toxic gas sensors are supplied precalibrated, and the sensitivity
of the sensor should not drift by more than 2% of full signal per month.
The full calibration procedure is not a requirement for normal operation of
the Foxcroft Gas Detectors. Full calibration is only necessary when it has
been determined that there is a problem with the sensor, and only after the
problem has been repaired, or the sensor has been replaced. However, full
gas calibration is a good safety procedure, and is recommended as such, in
this instruction manual, for the gas detector. If your on-site safety procedures
require a gas detector test (which they should), we recommend a short gas
leak test rather than a full calibration. There are two reasons for this:
1. The gas sensor is designed for ambient air conditions, and can eventually
be “poisoned” by repeated overexposure to the test and target gases.
This is usually noted as a gradual elevation in the zero reading over time
and exposure to the test and target gases.
2. If the calibration is done improperly, or with old test gas (it has a shelf
life listed on the cylinder), it could seriously impair the sensitivity and
function of the gas detector.
WARNING: Target calibration gas contains toxic gas and should only be used
by personnel who are fully trained in gas calibration procedures. All safety
procedures and warnings on the gas cylinder should be read, understood,
and observed.
7
The Calibration Book
Calibration
Blanking
Never leave caps
on when sensor
is in service
Figure 3
Calibration Tube
Connection
Figure 4
E-Z Cal Sensor Controls
8
Figure 5
Short Gas Leak Test
Short Gas Leak Test
Important: This test is not a calibration; it is only to test the gas sensor response to a gas leak. Short
gas leak tests can only be done with a known target concentration gas.
It is very important that this test sets off all the alarms and the target concentration gas level is
displayed on the LED display.
Full calibration is required if the test fails to set off alarms and the target concentration gas level is not
displayed on the LED display.
1.
The Remote alarm unit must be at zero on the LED display.
2.
Install the calibration nose in the collar plug; be sure the nose is sealed properly and is isolated
from the atmosphere.
3.
Connect the target calibration gas sample tubing to the nose.
4.
Apply target calibration gas with a known concentration.
5.
Wait for a stable reading to be obtained (five minutes is a suitable period).
6.
The known target gas concentration level should be indicated on the LED display and all the
alarms should be set off including the buzzer.
7.
If the target calibration gas level is indicated on the LED display and the alarms are set off
including the buzzer, test is complete. Remove calibration nose, LED display should zero in a
few minutes. Reset danger alarm.
8.
If the target calibration gas level is not indicated on the LED display and or fails to set off all
alarms a full calibration is required.
9
Full Sensor Calibration
Full Sensor Calibration
Each sensor is supplied precalibrated, and the sensitivity of the sensor should not drift by more then
2% of full signal per month. The oxygen sensor which has a single trimmer for span adjustment (see
page 12) and has a separate calibration routine.
Important: Full sensor calibration is only as accurate as the digital millivolt meter being used (or the
Toxic Gas Detector LED display), and the freshness of the target gas being used. So it is important to
use an accurate digital meter and a fresh target gas cylinder. The Toxic Gas Detector remote alarm unit
already has a factory precalibration and calibration should not be required. If you have reason to believe
that the display or alarm level calibration of the Detector remote alarm unit is off, we recommend that you
contact Foxcroft to arrange an “RMA”, to return the entire unit with the sensor for a complete calibration.
Foxcroft maintains a serial numbered calibration database for all of our gas detectors. Foxcroft does not
recommend electronic calibration of the remote unit in the field.
1.
The gas sensor enclosure mounting system allows easy zeroing and aspiration using the
calibration nose provided. With the plug in place and sealing caps fitted, the sensor is completely
isolated from the atmosphere. Removing the cap seals allows the calibration target gas to be
connected to one of the inlets and exhausted through the other. A flow of 500 milliliter/ minute is
recommended.
2.
Ensure the sensor is free from the target gas being measured either by purging the sensor with
an inert gas, or blanking the sensor from the atmosphere with the calibration nose supplied.
3.
Apply a target calibration gas of a known concentration to the sensor.
4.
Wait for a stable reading to be obtained (five minutes is a suitable period of time).
Important: It is very important to maintain weekly and monthly test logs (see pages 20-22). Regular
testing ensures the proper operation and life of the detector.
Input Connection
CN2 (40-200mV)
Span
Zero (4mA)
Gain
Figure 6
10
The Calibration Book
Full Sensor Calibration
CN2 (40-200mV)
Input Connection
Figure 7
Gain
Span
Zero (4mA)
Full Sensor Calibration Procedure
1.
Locate the calibration zero/span trimmers on the PCB located in the sensor enclosure or inside
the FX-1 enclosure.
2.
The circuit board has an additional coarse gain trimmer, which may also be used to calibrate
the sensor. However this should not be necessary for routine recalibration, and so should be
avoided.
3.
For calibration purposes, the signal may be monitored using either a digital multimeter inserted
in CN2 (across a 10 ohm precision resistance on the circuit board) 40-200mV or by the remote
alarm unit LED display.
4.
The gas sensor enclosure mounting system allows easy zeroing and aspiration using the
calibration nose provided. With the plug in place and sealing caps fitted, the sensor is completely
isolated from the atmosphere. Removing the sealing caps allows the calibtration target gas to
be connected to one of the inlets and exhausted through the other. A flow of 500 mls/min is
recommended.
5.
Ensure the sensor is free from the target gas being measured either by purging the sensor with
an inert gas, or blanking the sensor from the atmosphere with the calibration nose supplied.
6.
Adjust the zero trimmer until 0 ppm is shown on the LED display or 40mV.
7.
Apply a target calibration gas of a known concentration to the sensor.
8.
Wait for a stable reading to be obtained (five minutes is a suitable period of time).
11
The Calibration Book
Full Sensor Calibration
9. Adjust the span trimmer until the correct reading is shown on the LED display.
Or the voltage across CN2 is:
16 x (gas concentration) + 4 x 10mV
Range of Sensor
Example: Calibrating a hydrogen sulfide sensor to a range of 0-50ppm using a calibration gas
concentration of 20ppm: 16 x (20) + 4 x 10mV = 104mV
50
10. Reassemble, test complete.
Figure 8
Oxygen Sensors
Calibration should be carried out in ambient air, and is done simply by adjusting the span trimmer until
a reading of 20.9% on a scale of 0-25% is displayed on the LED display.
Figure 9
12
FX Easy Calibration
Performance Characteristics (Chlorine only)
Sensor Type Used
Expected Operating Life
Resolution
Temperature Range
Pressure Range
Pressure Coefficient
T90 Response Time
Relative Humidity Range
Maximum Zero Shift (20°C - 40°C)
Long Term Output Drift
Repeatability
Output Linearity
3CLH
Two years in air
0.1ppm
-20°C to +50°C
Atmospheric +/- 10%
No data
≤ 60 seconds
15-90% non-condensing
-0.2ppm equivalent
< 2% signal loss/year
2% of signal
Linear
N.B. All performance data is based on conditions at 20C, 50%RH and 1013mBAr.
Electrical Properties (Chlorine only)
Minimum Input Span
Maximum Input Span
Linearity @ 25°C
Thermal Drift (Input)
Linearisation
Output
Maximum Output Range
Operating Voltage
Thermal Drift (Output)
Output Accuracy
Protection
Maximum Loop Load
Physical Characteristics (Chlorine only)
Weight
Position Sensitivity
Storage Life
Recommended Storage Temperature
Linearisation
Warranty Period
5uA
+/-100uA
0.01% Full Scale
0.02% per °C
Linear Response
4-20mA, 2 wire loop powered
3.8 to 21mA
10 to 30VDC
2uA per °C
+/- 5uA
Reverse Polarity Protected
RLOAD = (Vsupply-10)*50
e.g. 700Ω at 24V
58g (including mounting accessory)
None
Six months in CTL Container
0-20°C
Linear Response
12 months from date of despatch
13
The Calibration Book
FX Easy Calibration
Calibration Notes
Recalibration is only possible if the output of the sensor at full scale is greater than 50% of the original
factory calibration. Failure can occur if:
1. 2. 3. 4. Attempts to recalibrate to a range less than 50% of the original factory calibrated range
The output of the sensor has fallen by more than 50% (replace sensor)
Incorrect span gas used (use correct span gas)
Insufficient time for output to settle after exposing sensor to span gas (apply span gas for 2-5
mins before setting 20mA level)
Transmitter Error Condition
Any time the error condition is set the output will be forced to 21mA and the LED will be held on. Carry
out the Reset function to reset the error.
Reset to Factory Calibration
1. 2. 3. 4. 5. 6. 7. Remove loop power from transmitter.
Hold down push button and connect loop power to transmitter.
LED will blink as soon as power is applied (approx. 2Hz).
Transmitter output set to 21mA.
Releasing button will start an 8 second timout period.
After 8 seconds the factory calibration will overwrite user calibration.
LED cleares and transmitter goes back into normal mode.
User Calibration Method
(Span gas = 20mA signal)
1. 2. 3. 4. 5. 6. 7. Connect loop power to the transmitter.
Apply required zero gas/air to transmitter for 2 minutes.
Hold down button until LED flashes at approx. 1Hz. (4mA level now set)
Apply required span gas to transmitter for 2 to 5 minutes.
Press and release button (20mA level now set)
There will be an 8-second timeout period and flashing LED approx. 8Hz.
Calibration is complete, LED clears and returns to normal mode.
14
The Calibration Book
FX Easy Calibration
Non Standard Span Gas Calibration (Span gas ±5% full range)
1. Calculate the mA signal expected for span gas.
Example:
1. Required 4-20mA range is 0-500ppm
5. Expected signal at 480ppm = (15.36mA + 4mA) = 19.36mA
2. Available span gas is 480ppm
3. Dynamic range is 16mA
6. Each time button is pressed signal increases by 40uA. When the output
reaches 20.8mA the next button press will take the output to 19.2mA.
Further button presses will again increase the output by 40uA.
4. Therefore 1mA = 31.25ppm
7. The output range available is 19.2mA to 20.8mA.
2. Carry out steps 1-4 of User Calibration Method
3. Press and release button to set 20mA level.
4. Continued momentary pressing of the button within an eight second period will trim the output by
40uA. When the required output is reached, allow the transmitter to timeout.
5. Calibration is complete, LED clears and returns to normal mode.
Non Standard Span Gas Calibration (Span gas not within ±5% of full range; current source required)
1. Measure the current of the sensor with a known gas concentration. This can then be used to
calculate the µA/ppm for the specific sensor.
2. Now calculate the expected current when the sensor is exposed to the full scale of target gas.
Example:
1. Required 4-20mA range is 0-500ppm
4. Therefore sensitivity = 0.11 uA/ppm
2. Available span gas is 300ppm
5. Expected sensor output at 500ppm = 55uA
3. Current from sensor when exposed to span
gas = 33uA
3. Connect current loop power to the transmitter.
4. Connect a current source to the transmitter. For oxidizing sensors (CO, H2S, SO2, NO, ...)
connect the negative to ‘SEN’ and positive to ‘CNT’. For reducing sensors (Cl2 or NO2) connect
the positive to ‘SEN’ and negative to ‘CNT’. ‘CNT’ and ‘REF’ terminals on the transmitter board
should be connected.
5. Set the current source to zero.
6. Hold down button until LED flashes at approx. 1Hz.
(4mA level now set in RAM)
7. Set the current source to the value calculated for the full scale of target gas.
8.
Press and release button
(20mA level now set into RAM)
9. There will be an 8-second timeout period and flashing LED approx. 8Hz.
10. Calibration is complete, LED clears and returns to normal mode.
15
The Calibration Book
FX Easy Calibration
Chlorine - Output vs Temperature
Figure 10
16
Gas Sensor Replacement
Gas sensor replacement in the Toxic Gas Detectors is easily done with minimal tools.
Tools required:
• Small Jeweler’s Screwdriver
• General Small Screwdriver
• Needlenose Pliers
1.
Disconnect the AC power from the detector.
2.
Remove the sensor enclosure cover by removing (4) screws.
3.
Remove the front cover of the sensor enclosure.
4.
Carefully pull off the orange wire connector.
5.
Unscrew the bulk head nut (see page 18 for diagram). Place the tips of a pair of needlenose
pliers in the two holes of the sensor bulk head nut. Turn the ring counterclockwise to loosen the
ring, and remove the entire sensor from the enclosure.
6.
The transmitter PC board is mounted to the sensor with disconnect pins. Hold the PC board by
the edges and carefully pull the board off of the sensor. Some very early sensors, pre- ”1994,”
had the PC board soldered directly to the sensor. This type is not removable. If you have this
type, stop here. Do not attempt to solder the new sensor to the transmitter board. The heat from
the soldering process will damage the new sensor. You will need to replace the entire sensor/
transmitter assembly. All new sensors have removable boards, so future sensor replacements
will not be hindered by the additional cost of the transmitter board.
9.
Remove the shorting wire from the gold pins on the new sensor, and carefully line up the 3 gold
pins on the new sensor with the 3 sockets on the bottom of the transmitter board. Press evenly
on the board until it fully seats on the gold pins.
10. Installation of the completed sensor/transmitter assembly is the reverse of its removal.
11. After completing the sensor replacement procedure, power-up the gas detector and allow it
to stabilize for 20 minutes (some sensor gas types take up to 24 hours to stabilize). The LED
display, should show 0.0 ppm +/-0.1 ppm. If the display is off by more than 0.2 ppm, or the cell
failure/problem light is blinking, the sensor requires a full sensor calibration.
12. Refer to page 9 and follow the short gas leak test.
WARNING: Even the ability of the gas sensor to sense toxic gas or low oxygen
levels must be verified on a regular basis. It is recommended that the gas sensor
be tested by means of a certified gas standard at least every six months.
WARNING: All functions of this FX-1500 Gas Detector must be checked and
verified on a regular basis.
17
The Calibration Book
Gas Sensor Replacement
4-20mA loop connector with wire and
CN@ 40-200 mV connector with wire
Calibration Nose
and O-ring
Bulkhead
Nut
O-ring
Gas Sensor
Figure 11
Cap Seals
Collar with O-ring
(3) 2-56 SS Screws
Transmitter Board
Figure 12
18
Parts Listing
Electronics
Item Number
1
2
3
4
5
6
7
8
9
Description
Gas Sensor Only
Gas Sensor Transmittor Only
Gas Sensor with Transmittor
Cap Seals
Calibration Nose with O-rng
Bulkhead Nut
Collar with O-ring
O-ring
(3) 2-56 SS Screws
19
Part Number
See specific gas type
See specific gas type
See specific gas type
FX-B017CS (set of 2)
FX-B017
FX-B020 nut
FX-B020
FX-B018
FX-B25678
Monthly Sensor Test Log
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20
Initials
Weekly Electronic Test Log
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21
Initials
Gas Sensor Replacement
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22
Initials
Service
System Repair
Customer Service Department
If you need spare parts, assistance in troubleshooting, or repair service, please contact Foxcroft
Customer Service at:
Foxcroft Equipment and Service, Co. Inc.
2101 Creek Road, P.O. Box 39
Glenmoore, PA 19343
Tel: (800) 874-0590
(610) 942-2888
Fax:
(610) 942-2769
Email:service@foxcroft.com
www.foxcroft.com
Customer Repair / Returns Policy
All systems returned for repair or replacement must be freight prepaid and include the following
information:
1.
A clearly written description of the malfunction.
2.
Name of person to contact and the phone number where they can be reached.
3.
Proper return address for shipping system back. Include preferred shipping method.
4.
A purchase order if the system is out of warranty to cover costs of repair.
5.
A Return Material Authorization Number (RMA) is required before shipping any products for
service. Call telephone number above to receive a RMA number.
NOTE: Returns will only be held at Foxcroft for 90 days. If a decision is not made regarding the
repair, the product will be returned.
23
Product Warranty
Foxcroft Equipment & Service warrants all products obtained hereunder to
be free from defects in material and workmanship for a period of one year
from the date of shipment. In the event of a product failure or defect requiring
warranty repair, the customer must obtain an RMA number by calling 1-800874-0590, before returning the product, at the customer’s expense to Foxcroft
for repair. Warrantor (Foxcroft Equipment and Service) will repair the unit,
without charges for parts, labor and return freight.
Foxcroft Equipment & Service is not responsible for damage to its products
through improper installation, maintenance, act of God, use or attempts
to operate such products beyond their functional capacity, intentionally or
otherwise, or for any unauthorized repair.
Buyer agrees to hold Foxcroft Equipment & Service harmless from all claims
for damages arising out of injury or death to any person or damage to any
facility, or any other property, or loss of use of any such property, whether
such person or property is on or off the installation or activity site for which
the equipment or material furnished hereunder is destined and whether such
damage, loss destruction or loss of use, injury or death results directly or
indirectly from a nuclear incident or for any other cause.
Statements and instructions set forth herein are based upon the best
information and practices known to Foxcroft Equipment & Service but it should
be assumed that every acceptable safety procedure is contained herein. Of
necessity this company cannot guarantee that actions in accordance with
such statements and instructions will result in the complete elimination of
hazards and it assumes no liability for accidents that may occur.
Serial Number Label of Gas Detector:
Foxcroft Equipment and Service, Co. Inc.
2101 Creek Road, P.O. Box 39
Glenmoore, PA 19343
Tel: (800) 874-0590
(610) 942-2888
Fax:
(610) 942-2769
Email:service@foxcroft.com
www.foxcroft.com
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