The 873DPX Dual pH/ORP/ISE Analyzer is an addition to the 873 family of electrochemical analyzers that extends capabilities to ion-specific measurements as well as pH and ORP. The

873DPX analyzer interprets the pH/ORP or specific ion concentration of aqueous solutions and displays measurement values in pH, mV, or ppm of the selected ion. It also measures solution temperatures for both cells, which may be displayed on demand, for automatic temperature compensation of pH and ISE (ion selective electrode) measurements.

The 873DPX can make dual (similar or different) measurements in a single solution. It can also make dual (similar or different) measurements in different solutions if the difference in potential between solutions does not exceed 5 V dc or 3.5 V ac. This capability allows for:

♦ Dual pH measurement

♦

Dual ORP measurement

♦ Dual ISE measurement

♦ Simultaneous pH and ORP measurement

♦ Simultaneous pH and ISE measurement

♦

Simultaneous ORP and ISE measurement

♦ pH corrected ISE measurement

The analyzer can accept inputs from two independent process measurement sensors (pH, ORP, or ion-specific) plus RTD temperature detectors for both sensors. The unit can also output two isolated analog signals proportional to any of the following:

♦ Measured values of both sensors

♦

Solution temperatures for both sensors

♦ Average of measured values for both sensors

♦ Ratio of measured values (Cell 1/Cell 2)

♦ Difference between measured values of both sensors (Cell 1 − Cell 2)

MI 611-190 – January 2021 1. Introduction

Instrument Features

Some of the features of the 873DPX Analyzer are:

♦ Metal Field Enclosure

♦ Dual Alarms

♦ Dual Analog Outputs

♦ EEPROM Memory

♦ Instrument Security Code

♦ Hazardous Area Classification

♦ Front Panel Display

♦ Application Flexibility

♦ Storm Door Option

Enclosure

The metal enclosure is designed for field or control room locations and may be panel, pipe, or surface mounted. It is constructed of cast aluminum coated with a tough epoxy-based paint.

The enclosure is watertight, dusttight, and corrosion-resistant, meeting the enclosure rating of

NEMA 4X, CSA Enclosure 4X, and IEC Degree of Protection IP-66. The unit fits in a

92 x 92 mm (3.6 x 3.6 in) panel cutout (1/4 DIN size). The enclosure also provides inherent protection against radio frequency interference (RFI) and electro-magnetic interference

(EMI).

Dual Alarms

Dual, independent, Form C dry alarm contacts, rated 5 A noninductive, 125 V ac/ 30 V dc are provided. The alarm status is alternately displayed with the current measurement value on the LED (light-emitting diode) display.

CAUTION

When the contacts are used at signal levels of less than 20 W, contact function may become unreliable over time due to the formation of an oxide layer on the contacts.

See “Alarm Contact Maintenance” on page 87.

No Battery Backup Required

Non-volatile EEPROM memory is used to protect all operating parameters and calibration data in the event of a power interruption.

Instrument Security Code

A combination code lock method, user configurable, provides protection of operational parameters from accidental or unauthorized access.

1. Introduction MI 611-190 – January 2021

Hazardous Area Classification

The instrument is designed to meet Class I, Division 2, Groups A, B, C, and D hazardous locations.

Front Panel Display

The instrument display consists of a 4-digit bank of red LEDs, as shown on the next page.

The 14.2 mm (0.56 in) display height provides visibility at a distance up to 6 m (20 ft) through a red-tinted, nonreflective, protective window on the front panel.

The measurement value is the normally displayed data. If other data is displayed due to prior keypad operations, the display automatically defaults to the measurement value 10 seconds after the last key is pressed. This feature is called “timing out.” The “timeout” time may be adjusted to any time between 3 and 99 seconds. You can prevent the “timeout” from occurring by pressing and holding the SHIFT key.

If no fault or alarm conditions are detected in the instrument, the measurement value is displayed steadily. If, however, fault or alarm conditions do occur, the display alternately shows the measurement and a fault or alarm message on a 1-second cycle.

Front Panel Keypad

The front panel keypad consists of eight keys. Some keys handle specific fixed functions; others perform split functions. You can select the upper function (green legend) of a fixed function key by pressing and holding the shift key as you press the split function key.

Figure 1. Front Panel Keypad and Display

ANALYZER TYPE

ANALYZER MODEL

MEASUREMENT VALUE

DISPLAY (4-DIGITS PLUS

DECIMAL POINT)

DUAL FUNCTION KEY

(PRESS/HOLD SHIFT AND

KEY FOR TOP FUNCTION.

PRESS KEY ONLY FOR

LOWER FUNCTION)

873 Dual pH/ORP/ISE

Analyzer

8.8.8.8.

mV pH

Cal Hi Alt Cel mV Slope

Cel2 ppm

MEASUREMENT

LEGEND UNITS

DISPLAY

SINGLE FUNCTION KEY

(PRESS KEY ONLY)

Temp Alm 1

Cal Lo

Setup

Shift Alm 2 Lock Enter

MI 611-190 – January 2021 1. Introduction

Application Flexibility

The 873DPX Analyzer offers application flexibility through its standard software package.

The software, which runs on the internal microprocessor, allows you to define and set operating parameters specific to your application. Such parameters fall into four general categories:

1. Measurement Range

2. Alarm Configuration

3. Diagnostics

4. Output Characterization

These parameters are stored in EEPROM nonvolatile memory and are maintained in the event of a power interruption.

Storm Door Option

This door is attached to the top front surface of the enclosure. It is used to prevent accidental or inadvertent actuation of front panel controls, particularly in field mounted applications.

The transparent door, hinged for easy access to front panel controls, permits a clear view of the display when closed.

Analyzer Identification

A data label, fastened to the side of the enclosure, provides model number and other information pertinent to the specific instrument. An example is shown in the figure below.

Figure 2. Typical Data Label

1. Introduction

Model Code

Dual pH/ORP/ISE Electrochemical Analyzer

Supply Voltage and Frequency

120 V ac, 50/60 Hz

220 V ac, 50/60 Hz

240 V ac, 50/60 Hz

24 V ac, 50/60 Hz

100 V ac, 50/60 Hz

Measurement Output

0 to 20 mA dc, isolated

4 to 20 mA dc, isolated

0 to 10 V dc, isolated

Enclosure

Field, Metal, Panel Mounting

Field, Metal, Surface Mounting — Fixed

Field, Metal, Pipe Mounting

Field, Metal, Surface Mounting — Movable

Electrical Certification (see Product Safety Specifications Section)

CSA, Ordinary Locations (except 220 and 240 V ac options)

FM, Ordinary Locations

FM, Nonincendive, Division 2 Locations

CSA, Nonincendive, Division 2 Locations (except 220 and 240 V ac options) (a)

Optional Selections

Storm Door

Special per Engineering Order

( a) Not available at time of printing .

MI 611-190 – January 2021

873DPX

-A

-B

-C

-E

-J

CGZ

FGZ

FNZ

CNZ

-7

-0

MI 611-190 – January 2021 1. Introduction

Standard Specifications

Supply Voltages

Supply Frequency

Output Signals

Ambient Temperature Limits

Measurement Ranges

Temperature Measurement Range

Temperature Compensation Range

Relative Humidity Limits

Accuracy of Analyzer Display

Accuracy of Analyzer Outputs

Analyzer Identification

Dimensions

Enclosure Mounting Options

Approximate Mass

Instrument Response

Measurement Damping

Alarms

Alarm Contacts

Alarm Indication

-A 120 V ac

-B 220 V ac

-C 240 V ac

-E 24 V ac

-J 100 V ac

50 or 60 Hz, ±3 Hz

I: 4 to 20 mA isolated

T: 1 to 10 V dc isolated

E: 0 to 20 mA isolated

-25 to +55°C (-13 to +131°F) pH: -2 to +16 pH

ORP: -999 to +1400 mV

ISE: 300 mV span with range limits of -999 and +1000 mV (displayed as ppm)

-17 to +199 °C (0 to 390°F)

-5 to +105 °C (23 to 221°F)

5 to 95%, noncondensing

±0.1% of upper range limit

±0.25% of upper range limit

Refer to Figure 2.

96(H) x 96(W) x 259(L) mm

-W: Metal Field Mount/Panel Mount

-X: Metal Field Mount/Surface Mount

-Y: Metal Field Mount/Pipe Mount

-Z: Metal Field Mount/Movable Surface Mount

Metal Field Enclosure (with brackets)

Panel Mounting 1.28 kg (3.9 lb)

Pipe Mounting

Fixed Surface Mounting

2.54 kg (5.6 lb)

2. 46 kg (5.4 lb)

Movable Surface Mounting 3.38 kg (7.4 lb)

2 seconds maximum (when zero measurement damping is selected in

Configuration Code).

Temperature Response is 15 seconds maximum.

Choice of 0, 10, 20, or 40 second, configurable from keypad. Damping affects displayed parameters and analog outputs.

Two alarms configurable via keypad. Individual set points continuously adjustable 0 to full scale via keypad. Hysteresis selection for both alarms; 0 to 99% of full scale value, configurable via keypad. Dual timers for both alarms, adjustable 0 to 99 minutes, configurable via keypad.

Allows for on/off control with delay. Timers can be set to allow chemical feed, then delay for chemical concentration control.

Two independent, nonpowered Form C contacts. Rated 5 A noninductive, 125 V ac/30 V dc (minimum current 1 A). Inductive loads can be driven with external surge-absorbing devices installed across contact terminations.

CAUTION : When the contacts are used at signal levels of less than 20

W, contact function may become unreliable over time due to the

formation of an oxide layer on the contacts. See “Alarm Contact

Maintenance” on page 87.

Alarm status alternately displayed with measurement on LED display.

1. Introduction MI 611-190 – January 2021

RFI Susceptibility

Electromagnetic Compatibility (EMC)

10 V/m from 27 MHz to 1000 MHz, when all sensor and power cables are enclosed in a grounded conduit.

The Model 873DPX Electrochemical Analyzer, 220 V ac, or 240 V ac systems with Metal Enclosure, comply with the requirements of the

European EMC Directive 89/336/EEC when the sensor cable, power

cable, and I/O cables are enclosed in rigid metal conduit. See Table 1.

The plastic case units comply with the European EMC Directive

89/336/EEC when mounted in a solid metal enclosure and the I/O cables extending outside the enclosure are enclosed in solid metal

conduit. See Figure 1.

Electrical Safety Specifications

Testing Laboratory,

Types of Protection, and

Area Classification Application Conditions

FM for use in general purpose (ordinary) locations.

FM nonincendive for use in Class I, Division 2, Groups

A, B, C, and D; and suitable for Class II, Division 2,

Groups F and G, hazardous locations.

Temperature Class T6.

CSA (Canada): for use in general purpose (ordinary) locations.

CSA (Canada): Suitable for use in Class I, Division 2,

Groups A, B, C, and D.

24 V, 100 V, and 120 V ac (Supply option -A, -E, -J) only.

Electrical Safety

Design Code

FGZ

FNZ

CGZ

CNZ

NOTE

The analyzer has been designed to meet the electrical classifications listed in the table above. For detailed information on the status of agency approvals, contact Global

Customer Support.

CAUTION

1. When replacing covers on the 873DPX case, use Loctite (Part No. S0106ML) on the threads of screws for the front cover and Lubriplate (Part No. X0114AT) on the threads of screws for the rear cover. Do not mix.

2. Exposure to some chemicals may degrade the sealing properties of Polybutylene

Teraethalate and Epoxy Schneider Electric legacy relay 276XAXH-24 used in relays

K1 and K3. These materials are sensitive to acetone, MEK, and acids. Periodically inspect relays K1 and K3 for any degradation of properties and replace if degradation is found.

MI 611-190 – January 2021 1. Introduction

2. Installation

Mounting to a Panel (873DPX-xxWxxx)

The metal field-mounted enclosure can also be mounted to a panel. The procedure is as follows:

1. Refer to DP 611-162 for panel cutout data.

2. Make cutout in panel in accordance with DP 611-162.

3. Remove rear bezel and insert analyzer through panel cutout. Temporarily hold in place.

4. From rear of panel, slide plastic clamp onto enclosure until clamp latches (2) snap into

two opposing slots on longitudinal edges of enclosure. See Figure 3.

5. Tighten screws (CW) on clamp latches until enclosure is secured to panel.

6. Reassemble rear bezel to enclosure using the four captive screws.

Figure 3. Mounting to a Panel

CLAMP LATCH

PLASTIC CLAMP

REMOVABLE REAR BEZEL

PANEL THICKNESS NOT

TO EXCEED 20 mm (0.8 in)

PLASTIC CLAMP

SLOTS IN

LONGITUDINAL

EDGES OF

ENCLOSURE

CLAMP LATCH SCREW (2)

CLAMP LATCH (2)

MI 611-190 – January 2021 2. Installation

Mounting to a Pipe (873DPX-xxYxxx)

1. Locate horizontal or vertical DN 50 or 2-inch pipe.

2. Assemble universal mounting bracket as follows: a. Place hex bolts (5) through spacer (3) into support bracket (2).

b. Slide nylon washers (11) over bolts (5).

c. Slide bolts through pipe mounting bracket (1) and fasten assembly tightly with hardware designated 7, 6, and 13.

d. Attach pipe mounting bracket (1) to pipe with U-bolts (12) using hardware designated 6, 7, and 13.

3. Slide analyzer into support bracket and slide strap clamp (4) onto analyzer. Using two screws. nuts, and washers, attach strap clamp to support bracket and secure analyzer.

4. Lift entire assembly of Step 3 and, secure mounting bracket to pipe, using two Uclamps, nuts and washers.

2. Installation

MOUNTING

BRACKET

MI 611-190 – January 2021

Figure 4. Mounting to a Pipe (Horizontal or Vertical)

SUPPORT

BRACKET

STRAP

CLAMP

VERTICAL DN50 OR

2-INCH PIPE

MOUNTING

BRACKET

0.312-18 NUTS

(4 PLACES

)

0.190-32

SCREWS (2)

U-CLAMP (2

)

STRAP

CLAMP

NOMINAL DN50 OR

2-INCH PIPE. HORI-

ZONTAL PIPE SHOWN.

TWO U-CLAMPS ARE

USED TO SECURE

BRACKET TO PIPE.

PIVOT BOLT; MOUNTED ENCLOSURE

CAN BE ROTATED UP TO 60-DEGREES

IN VERTICAL PLANE

12 13

MI 611-190 – January 2021 2. Installation

Mounting to a Surface — Fixed Mount

(873DPX-xxXxxx)

1. Locate mounting surface for analyzer.

2. Referring to Figure 5, use mounting bracket as template for drilling four holes into

mounting surface. Notice that holes in the mounting bracket are 8.74 mm (0.344 in) in diameter. Do not attach mounting bracket to surface at this time.

3. Assemble universal mounting as follows: a. Place hex bolts (5) through spacer (3) into support bracket (2).

b. Slide nylon washers (11) over bolts (5).

c. Slide bolts through universal mounting bracket (1) and fasten assembly together with hardware designated 7, 6, and 12.

d. Attach universal mounting bracket (1) to wall.

4. Slide analyzer into support bracket and slide strap clamp (4) onto analyzer. Using two screws, nuts, and washers, attach strap clamp to support bracket and secure analyzer.

5. Lift entire assembly of Step 4, align mounting bracket holes with mounting surface holes and use four user-supplied bolts, nuts, and washers to attach mounting bracket to surface.

2. Installation MI 611-190 – January 2021

Figure 5. Mounting to a Surface, Fixed Mount

SURFACE (REFERENCE)

SPACER

STRAP

CLAMP

MOUNTING

BRACKET

0.190-32

SCREWS (2)

USER

SUPPLIED

STRAP

CLAMP

SUPPORT

BRACKET

PIVOT BOLT (MOUNTED

ENCLOSURE CAN BE

ROTATED UP TO 60-DEGREES

IN VERTICAL PLANE)

MI 611-190 – January 2021 2. Installation

Mounting to a Surface — Movable Mount

(873DPX-xxZxxx)

1. Locate surface on which to mount the analyzer. Also refer to PL 611-016.

2. Referring to Figure 6, use wall bracket (12) as a template for drilling four holes into

mounting surface. Note that the holes in the wall bracket are 9.53 mm (0.375 in) in diameter.

3. Attach wall bracket (12) to surface using four user-supplied bolts, washers, and nuts.

4. Assemble universal mounting as follows: a. Insert hex bolts (5) through spacer (3) into support bracket (2).

b. Slide nylon washers (11) over bolts (5).

c. Slide bolts through universal mounting bracket 91) and fasten assembly finger tight with hardware designated 9, 10, and 16.

5. Slide analyzer into support bracket and slide strap clamp (4) onto analyzer. Using two screws, nuts, and washers, attach strap clamp to support bracket and secure analyzer.

6. Lift entire assembly of Step 5, align mounting bracket and wall bracket pivot bolt holes, and then insert pivot bolt through wall and mounting bracket into nylon washer and locking nut.

7. Rotate bracket and analyzer assembly in horizontal plane to desired position. Lock in place using screw and washer.

2. Installation MI 611-190 – January 2021

WALL BRACKET

FOUR BOLTS

(USER-SUPPLIED)

SPACER

Figure 6. Mounting to a Surface — Movable Mount

PIVOT BOLT (0.250-20) FOR

HORIZONTAL PLANE ROTATION

SUPPORT

BRACKET

STRAP CLAMP

LOCK MOUNTING BRACKET

IN PLACE WITH 0.190-32

SCREW AND WASHER

PIVOT BOLT

SUPPORT BRACKET

STRAP CLAMP

PIVOT BOLT (0.312-18)

FOR VERTICAL PLANE

ROTATION

NYLON WASHER

AND NUT

MOUNTING

BRACKET

0.190-32 SCREWS (2)

MI 611-190 – January 2021 2. Installation

Wiring Connections

Wiring installation must comply with any existing local regulations.

NOTE

To maintain a rating (NEMA 4X, CSA Enclosure 4X, or IEC Degree of Protection

IP-66), conduits with the proper fitting must be used (see Table 1 on page 32). Alarm

wires should run through the same conduit as the power wires. Sensor wires should run through the same conduit as analog output wires.

The 873DPX Analyzer is equipped with a rear cover terminal board to facilitate sensor wiring.

The rear cover terminal strips are connected by a ribbon cable to the terminal blocks inside the analyzer. Wiring can be installed by removing the rear cover for the 873 and making sensor connections outside of the analyzer housing.

NOTE

The rear cover terminal strip may only be used with preamplified (or low impedance) sensors such as the 871PH or the 871A-2. The 871A-1, the 222F, or any sensors of other companies without a preamplifier (high impedance) may NOT be connected to this terminal board unless a remote preamplifier is used (Part No.PS290AA or

PS290AB). Otherwise, non-preamplified sensors must be wired directly to the terminal strips inside the analyzer. It is recommended that the remote terminal board be removed from the rear cover if it is not in use. First, disconnect the ribbon cable from the terminal blocks and then unscrew terminal board on rear cover and remove.

CAUTION

When the contacts are used at signal levels of less than 20 W, contact function may become unreliable over time due to the formation of an oxide layer on the contacts.

See “Alarm Contact Maintenance” on page 87.

2. Installation MI 611-190 – January 2021

Foxboro Sensors with Integral Preamplifiers

(871PH, 871A-2)

Use the following procedure to connect Foxboro sensors with preamplifiers to terminal blocks on

the Rear Cover Terminal Board and the Instrument Terminal Board (see Figure 7):

1. Remove back cover to provide access to rear cover terminal board.

2. Route sensor wires through conduit openings at bottom of case.

3. On the Instrument Terminal Board, connect Alarm 1 and Alarm 2 wires to TB3, as shown in the diagram. Failsafe operation requires that connections be made between contacts NC and C, and that the alarms be configured active.

4. On the Instrument Terminal Board, connect wires for analog outputs to TB4 as shown in the diagram.

5. On the Rear Cover Terminal Board, connect signal wires from Sensor 1 to the terminal block marked Cell 1 as shown in the diagram.

6. On the Rear Cover Terminal Board, connect signal wires from Sensor 2 to the terminal block marked Cell 2 as shown in the diagram.

7. On the Instrument Terminal Board, connect power wires to terminal block TB1, as shown in the diagram. The earth (ground) connection from the power cord should be connected to the ground stud located on the bottom of the enclosure.

NOTE

To obtain pH correction when measuring pH and ion-selective activity simultaneously, the pH sensor MUST be connected to Cell 1.

MI 611-190 – January 2021 2. Installation

SENSOR 2

Figure 7. Wiring Diagram for Foxboro Sensors with Preamplifiers

871PH

OR 871A-2

REAR COVER

TERMINAL BOARD

871PH

OR 871A-2

1 BK

BK 1

1 2 3

CELL 2

3A 4 5 6 7

2 WH

RTD

WH 2

3 RD

RD 3

1 2 3

CELL 1

3A 4 5 6 7

4 GRN (SOL. GND) SENSOR 1

(SOL. GND) CLR 4 5 ORANGE

CLR 5

POWER TO PREAMP

+BRN 6

(-)BLU 7

GROUND LUG

6 BRN +

7 BLU (-)

POWER TO

PREAMP

NOTE: 3-A TERMINALS NOT USED.

PRIOR TO JUNE 2016

RIBBON CABLE-TO-TERMINAL

BOARD WIRE CONNECTION

Terminal

No.

TB5:

TB2:

Cable

Color gray violet blue green yellow orange red brown blue/white green/white yellow/white orange/white red/white brown/white black white

INSTRUMENT

TERMINAL

BOARD

TB2

1 2 3 3A 4 5 6 7

L2 L1

TB1 TB3

2- 2+ 1- 1+

TB5

RIBBON CABLE

TO INSTRUMENT

TERMINAL BOARD

OUTPUT 2

OUTPUT 1

NC C NONCC NO

LO HI

TB4

AFTER JUNE 2016

RIBBON CABLE-TO-TERMINAL

BOARD WIRE CONNECTION

(a)

Terminal

No.

TB2/Cell 1:

TB5/Cell 2:

Cable

Color gray violet blue green yellow orange red brown gray violet blue green yellow orange red brown

(a)

Two cable labels, TB2/Cell 1 and

TB5/Cell 2 , are now installed on the ribbon cable.

POWER EARTH

TO GROUND LUG

ON CASE

ALARM 2 ALARM 1

2. Installation MI 611-190 – January 2021

Foxboro Sensors without Preamplifiers (871A-1 or

222F)

Use the following procedure to connect Foxboro sensors without preamplifiers to terminal blocks

on the Instrument Terminal Board (see Figure 8):

1. Remove back cover to provide access to rear cover terminal board.

( Do not connect anything to the Rear Cover Terminal Board.

)

2. Remove all ribbon cable connections from the Instrument Terminal Board terminal blocks. It is recommended that the rear cover terminal board be unscrewed and removed from the rear cover.

3. Route sensor wires through conduit opening at bottom of case.

4. On the Instrument Terminal Board, connect Alarm 1 and Alarm 2 wires to TB3, as shown in the diagram. Failsafe operation requires that connections be made between contacts NC and C, and that the alarms be configured active.

5. On the Instrument Terminal Board, connect wires for analog outputs to TB4 as

shown in Figure 8.

6. On the Instrument Terminal Board, connect signal wires from Sensor 1 to terminal

block TB2 as shown in Figure 8.

7. On the Instrument Terminal Board, connect signal wires from Sensor 2 to terminal

block TB5 as shown in Figure 8.

8. On the Instrument Terminal Board, connect power wires to terminal block TB1, as

shown in Figure 8. The earth (ground) connection from the power cord should be

connected to the ground stud located on the bottom of the enclosure.

MI 611-190 – January 2021 2. Installation

Figure 8. Rear Panel (Instrument) Wiring for Foxboro Sensors without Preamplifiers

WH(COAX)SHIELD

SENSOR 1

SENSOR 2

(SAME WIRING

AS SENSOR 1)

TB2

1 2 3 3A 4 5 6 7 2- 2+ 1- 1+

TB5

1 2 3 3A 4 5 6 7

TB4

L2 L1

TB1 TB3

NC C NONCC NO

LO HI

POWER

EARTH

TO GROUND LUG

ON CASE

ALARM 2 ALARM 1

871A-1

SENSOR 1

TB2

1 2 3 3A 4 5 6 7 2- 2+ 1- 1+

TB4

222F

2. Installation MI 611-190 – January 2021

Sensors of Other Companies

Use the following procedure to connect sensors of other companies without preamplifiers to terminal blocks on the Instrument Terminal Board:

1. Remove back cover to provide access to rear cover terminal board.

( Do not connect anything to the Rear Cover Terminal Board.

)

2. Remove all ribbon cable connections from the Instrument Terminal Board terminal blocks. It is recommended that the rear cover terminal board be unscrewed and removed from the rear cover.

3. Route sensor wires through conduit opening at bottom of case.

4. On the Instrument Terminal Board, connect Alarm 1 and Alarm 2 wires to TB3, as

shown in Figure 9. Failsafe operation requires that connections be made between

contacts NC and C, and that the alarms be configured active.

5. On the Instrument Terminal Board, connect wires for analog outputs to TB4 as

shown in Figure 9.

6. On the Instrument Terminal Board, connect signal wires from Sensor 1 and its RTD

to the terminal block TB2 as shown in Figure 9.

7. On the Instrument Terminal Board, connect signal wires from Sensor 2 and its RTD

to the terminal block TB5 as shown in Figure 9.

8. On the Instrument Terminal Board, connect power wires to terminal block TB1, as

shown in Figure 9. The earth (ground) connection from the power cord should be

connected to the ground stud located on the bottom of the enclosure.

MI 611-190 – January 2021 2. Installation

Figure 9. Rear Panel (Instrument) Wiring for Sensors of Other Companies (without Preamplifiers)

SENSOR 1

SENSOR 2

(SAME WIRING

AS SENSOR 1)

TB2

1 2 3

L2 L1

3A 4 5 6

TB5

TB1 TB3

2- 2+ 1- 1+

TB4

NOTES

1.TO PREVENT SIGNAL DEGRADATION,

CABLE LENGTH MUST BE CONSIDERED.

2.SOLUTION GROUND MUST BE WIRED TO A

METALLIC MATERIAL IN CONTACT WITH THE

PROCESS SOLUTION.

3.USER-SUPPLIED 100-OHM PLATINUM RTD

(DIN 43760).

NC C NONCC NO

LO HI

POWER

EARTH

TO GROUND LUG

ON CASE

ALARM 2 ALARM 1

Rigid Metal

Semi-Rigid Plastic

Semi-Rigid Plastic Metal Core

Flexible Plastic

Table 1. Recommended Conduit and Fitting

(Due to Internal Size Constraints)

Conduit

1/2-inch Electrical Trade Size

T&B* LTC 050

Anaconda Type HC,

1/2-inch

T&B #EFC 050

Fitting

T&B* #370

T&B #LT 50P or

T&B #5362

T&B #LT 50P or

T&B #5362

T&B #LT 50P or

T&B #5362

*Thomas & Betts Corp., 1001 Frontier Road, Bridgewater, NJ 08807-0993

3. Operation

Overview

The 873DPX functions in either of two modes, OPERATE or CONFIGURE (Setup). In the

OPERATE mode, the instrument automatically displays a measurement (or temperature) value and outputs two analog signals proportional to two user-selected measurement or temperature values. In the OPERATE mode, you can display the solution temperature or any parameter setting. In the CONFIGURE mode, you can enter and/or modify any previously entered parameter. All 873 analyzers are shipped configured with either factory default settings or userdefined parameters, as specified by the sales order. To use either mode, you must understand the functions of the keypad and the display.

Display

The instrument display, as shown in Figure 10, consists of two parts: (1) a

measurement/parameter settings display, and (2) a backlit display of measurement units. The measurement value may be displayed as any one of following:

♦ pH — expressed in pH units

♦ ORP — expressed in mV

♦

ISE — expressed in ppm

♦ Temperature — expressed in ºC or ºF

♦

Average of Sensors 1 and 2 — expressed in pH, mV or ppm

♦ Difference of Sensors 1 and 2 — expressed in pH, mV or ppm

♦ Ratio of Sensors 1 and 2 — expressed as a %

If you want to change from one display to another or to display anything other than the selections listed above, you must use various keypad functions, as described in the next section. You may also configure the display to toggle between Sensor 1 and Sensor 2 measurement value.

Keypad

The keypad, shown in , consists of eight keys, six of which are dual function. The white lettered keys represent normal functions and the green lettered keys represent alternate functions To operate a white lettered function key, just press the key. To operate a green lettered function key, press/hold the SHIFT key and then press the function key. The notation used to describe this

operation is SHIFT + (key). All key functions are described in Table 2 on page 34.

MI 611-190 – January 2021

Key

3. Operation

Figure 10. Model 873DPX Keypad and Display

873 Dual pH/ORP/ISE

Analyzer

8.8.8.8.

Cal Hi Alt Cel mV mV pH

Slope

Cel2 ppm

Temp Alm 1

Cal Lo

Setup

Shift Alm 2 Lock Enter

Table 2. Keypad Functions

Function

Press and hold this key to actuate the green dual-function keys. Holding the SHIFT key after pressing any function key delays the 10-second timeout, allowing you to view the display as long as you hold the key.

Shift

Press this key to display a value or code for a setup entry. You can also use this key to execute an action or selection or to store a value into memory.

Enter

Alt Cel

Temp

ALT CEL: Press/hold SHIFT and press this key to display the measurement value of the alternate cell.

TEMP: Press this key to display current solution temperature in C or F. If a dot is displayed following the C or F, the value displayed is a manual entry of temperature that overrides the actual measured value for temperature compensation.

Cal Hi

CAL HI: Press/hold SHIFT and press this key to access the upper calibration function of the analyzer.

ALM 1: Press this key to display and/or change the set point of Alarm 1.

Alm 1

3. Operation

Key

Cal Lo

MI 611-190 – January 2021

Table 2. Keypad Functions (Continued)

Function

CAL LO: Press/hold SHIFT and press this key to access the lower calibration function of the analyzer.

ALM 2: Press this key to display and/or change the set point of Alarm 2.

Alm 2 mV

Next mV: Press/hold SHIFT and press this key to display the measurement value in absolute millivolts.

NEXT: Press this key to select a digit or setup entry.

Setup

SETUP: Press/hold SHIFT and press this key to access the configuration entry function.

LOCK: Press this key to display and/or change the security lock state of the instrument.

Lock

Slope

SLOPE: Press/hold SHIFT and press this key to display the calibration slope value in millivolts/pH or millivolts/ppm decade.

INCREMENT: Press this key to increase the display count by one. Press and hold to increase count at a rate of approximately one per second.

NOTE

Pressing NEXT and INCREMENT simultaneously allows you to step backward through the Setup program or digit place movement. Note, however, that you cannot reverse number count by this procedure. Pressing and holding SHIFT and ENTER simultaneously overrides the 10-second wait between Setup entries.

Mode

When you turn power on, the 873DPX analyzer runs in the OPERATE mode. The instrument first conducts a self-diagnostic test and then automatically displays the selected display value (see

CELL code description, Chapter 4).

While in the Operate Mode, you may display the measurement, the solution temperature, and all parameter settings as configured in the Configuration Setup Entries and Basic Setup Entries

described in Chapter 4

MI 611-190 – January 2021 3. Operation

Temp Key

To view the process temperature, push TEMP. The display then changes from the current display to the solution temperature (or manually entered override value) for the primary sensor.

The display consists of a rounded whole number plus the temperature units (ºC or ºF). The units display alternately switches between ºC (or ºF) and the tenths of degrees measurement value.

Once the TEMP key has been pressed, the INCREMENT ( Δ ) key toggles the temperature between ºC and ºF, and also allows you to activate manual temperature compensation. Pushing Δ while in the TEMP mode causes the display to sequence from the current value through a series of displays similar to that shown in the following example:

(1)

77.F

77.0

(2)

77.F.

77.0

(3)

25.C

25.0

(4)

25.C.

25.0

When a decimal point after the C or F is present, this indicates that the process temperature is compensated manually at the temperature displayed, thus overriding the automatic temperature compensation function (i.e., manual temperature compensation is active). If you want to use another manual compensation temperature value, press NEXT + Δ repeatedly to change the display to the desired temperature and then press ENTER. The process will then be compensated for the new displayed temperature value. To return to automatic compensation, sequence the display (using the Δ button) to remove the decimal point after C or F. Note, however, that you cannot adjust automatic temperature compensation by this procedure. To adjust temperature in

the automatic mode, refer to Chapter 5

When dual sensors are used, you can display the process temperature (or manually adjusted temperature) of the alternate sensor by pressing and holding NEXT before pressing the TEMP key. The Cel2 legend is then illuminated and the process temperature (or manually adjusted temperature) for the alternate sensor appears on the display. Note that you cannot adjust the temperature of the alternate sensor via this procedure.

View Setup Entries

You may display Setup Entries at any time. To view any of the Setup Entries, follow the

procedures given in “Configuration Setup Entries” on page 38 or “Basic Setup Entries” on page 53, but do not UNLOCK the instrument.

When viewing Setup Entries, you may page through the parameters as rapidly as you wish by pressing SHIFT + SETUP and then pressing NEXT one or more times. However, once you have pressed ENTER to read a parameter value (value is displayed for 10 seconds), you must wait 10 seconds for the parameter symbol to reappear. The parameter symbols appear for 10 seconds also.

If you do not press another key within 10 seconds, the display defaults to the measurement. This feature is called timing out . To avoid timing ou t on any display, push and hold SHIFT. The time out time may be adjusted to any value between 3 and 99 seconds by using the tOut parameter. To

make changes to any Configuration Setup Parameter, see the section on “Configuration” on page 37.

4. Configuration

Overview

This instrument is shipped with either factory settings (default values) or user-defined settings, as

specified in the sales order. Table 3, “Configuration Setup Entries,” on page 39 lists all the

parameters that are frequently changed. Table 4, “Basic Setup Entries,” on page 53 lists

parameters that are calibration oriented. Both tables list the parameter identifier symbol, the name of the parameter, and a space for you to write your own values.

The configuration process consists of entering and/or modifying parameters to make the Analyzer function to your particular needs. This chapter explains how to enter and change specific items via the keypad. Because reconfiguration may also involve wiring or jumper changes, you must be sure that you check all such items before placing the Analyzer into service either on startup or following a parameter change of any kind.

You enter all parameters as 4-digit numerical codes, selecting the code from tables specific to each parameter. For parameters that are entered as direct 4-digit values, however, no table is supplied.

The configuration process consists of four simple steps:

1. Write down all your parameter settings in the spaces provided in the configuration tables.

2. Unlock the instrument.

3. Select the parameter entry identifier on the display and enter the 4-digit codes.

4. Lock the instrument.

Configure Mode

The Configure Mode is protected through two levels of security, one for Configuration Setup

Entries and another for Basic Setup Entries . Note that every configuration change starts with unlocking the instrument, which is accomplished by entering a security code at the keypad.

MI 611-190 – January 2021 4. Configuration

Security Code

The Analyzer uses two levels of security. The first level protects against unauthorized change of the parameters Temp, Alm 1, Alm 2, Cal Lo, Cal Hi , and all the Configuration Setup Entries . The second level protects against the remaining setup entries, called Basic Setup Entries . There are 32 such parameters.

Note that any of the parameters discussed above can be viewed (but not changed) when the

Analyzer is in the locked state. When displaying a parameter in the locked state, the digits do not flicker. Any attempt to change the parameter while in this mode causes the message Loc to appear on the display.

You use the same security code to unlock the unit in both levels of security. When the unit is unlocked at the first level (see Unlocking Analyzer Using Security Code ), the unit remains unlocked until you take a positive action to lock the unit again (see Locking Analyzer Using Security Code ).

However, when the unit is unlocked using the bL entry at the second level of security (see Basic

Setup Lock Control ), it remains unlocked only as long as you access any one of the Basic Setup

Entries. As soon as the Analyzer defaults to the current measurement value (i.e., “times out”), the second level of security automatically locks again. You must execute an unlock procedure, therefore, to reaccess Basic Setup Entries .

Unlocking Analyzer Using Security Code

The procedure for unlocking the Analyzer is:

1. Press LOCK. Display will read Loc.

2. Press NEXT and then press NEXT + INCREMENT ( Δ ) repeatedly until the security code is displayed (factory set at 0800).

3. Press ENTER. Analyzer will then read uLoc , indicating that it is now in the unlocked state.

Locking Analyzer Using Security Code

The procedure for locking the Analyzer is:

1. Press LOCK. Display will read uLoc .

2. Press NEXT and then press the NEXT + INCREMENT ( Δ ) keys repeatedly until the security code is displayed (set at 0800 by factory).

3. Press ENTER. Analyzer will then read Loc , indicating that it is now in the locked state.

Configuration Setup Entries

Configuration setup entries consist of 21 parameters. Because these parameters are process

oriented, access to them is passcode protected. Table 3 lists each parameter (entry identifier) in

the same sequence as seen on the display, the name of the parameter, and a space for recording your particular setting. A detailed description of each parameter is given in the explanatory text following the table.

4. Configuration

Table 3. Configuration Setup Entries

Att2**

AFt2

AdL2

AOUt

H0 1

***

L0 1

***

H0 2

***

L0 2

UL 1

LL 1

UL 2

LL 2

Ut L

Lt L

Parameter

Identifier

CELL

Hold

AC 1

Att1

AFt1

AdL1

AC 2

Parameter/Value Accessed

Configuration of Display and Damping

Hold and sets the Analog value in Hold

Alarm 1 Configuration

Measurement Alarm Assignment

Low/High/Instrument plus passive/active state

Hysteresis

Alarm 1 Trigger Time

Alarm 1 Feed Time

Alarm 1 Delay Time

Alarm 2 Configuration

Measurement Selection

Low/High/Instrument plus passive/active state

Hysteresis

Alarm 2 Trigger Time

Alarm 2 Feed Time

Alarm 2 Delay Time

Assignment of Analog Outputs

100% Analog Output - Output 1

0% Analog Output - Output 1

100% Analog Output - Output 2

0% Analog Output - Output 2

User-Defined Upper Measurement Error - Cell 1

User-Defined Lower Measurement Error - Cell 1

User-Defined Upper Measurement Error - Cell 2

User-Defined Lower Measurement Error - Cell 2

User-Defined Upper Measurement Error - Both Cells

User-Defined Lower Temperature Error -Both Cells

* Not displayed if disabled via AC1 parameter.

** Not displayed if disabled via AC2 parameter.

*** Not displayed if disabled via AOUt parameter.

MI 611-190 – January 2021

1000

0000

1403

Factory

Default

Values

User

Settings

00.00

1203

14.00

00.00

14.00

00.00

100.0

000.0

00.00

12.00

14.00

00.00

14.00

00.00

MI 611-190 – January 2021 4. Configuration

Changing Setup Parameters

To change any of the Configuration Setup parameters listed in the table above, use the following procedure:

1. Unlock Analyzer.

2. Press SHIFT + SETUP. Release both keys.

3. Press NEXT one or more times until the parameter you want to change is displayed.

4. Press ENTER. The 4-digit code for that parameter then appears.

5. Press/hold NEXT to select the digit you wish to change and press INCREMENT ( Δ ) to change the digit. Repeat until the desired code or value is displayed.

6. Press ENTER.

7. Lock Analyzer.

NOTE

You should set the configuration setup parameters whenever you make any changes to

FSC.

Configuration of Display and Damping (CELL)

The CELL parameter determines the type of measurement to be displayed on the Analyzer front panel and the amount of damping applied to the measurement.

The Display Assignment Digit (Digit 1) selects the measurement (or calculated ratio, difference, or average) value to be displayed. In addition, if Digit 1 is set to 0, the display alternates between measurement values of Sensors 1 and 2.

The Dual Cell Configuration Digit (Digit 2) should be set to 0 if operating in dual sensor mode and to 1 in single sensor mode. “0” means normal dual cell operation. “1” means that if a cell is not configured on both alarms, the output and display modes of that cell are ignored. If both cells are configured (ratio is displayed), neither cell is ignored, regardless of the setting of Digit 2.

The Damping Selection Digits (Digits 3 and 4) select the amount of damping applied to each sensor (Digit 3 for Sensor 1 and Digit 4 for Sensor 2). Damping time refers to an interval over which all measurement values are averaged. Damping also affects temperature displays and analog outputs.

4. Configuration MI 611-190 – January 2021

Digit 1

Display Assignment

Toggle Cell 1 and 2

Measurement

Cell 1 Measurement

Cell 2 Measurement

Temperature Cell 1

Temperature Cell 2

Digit Not Used

Average Cell 1 and Cell 2

Measurement

Ratio

(Cell 1/Cell 2) x 100

Digit Not Used

Difference (Cell 1 - Cell 2)

CELL Configuration Codes

Digit 2

Dual Cell Configuration

Dual Cell

Operation

Single Cell

Operation

Digit

Not

Used

Digit 3

Damping Cell 1

No Damping

10 Seconds

20 Seconds

40 Seconds

Digit

Not

Used

Digit 4

Damping Cell 2

No Damping

10 Seconds

20 Seconds

40 Seconds

Digit

Not

Used

Holding the Analog Outputs and Alarms (Hold)

This parameter sets the HOLD characteristics for both analog outputs.

When HOLD is activated, the analog outputs freeze at particular values determined by the setting of this parameter. The various codes are shown in the table below.

To use this feature, unlock the Analyzer, press SETUP, and then press NEXT repeatedly until the identifier HOLD is displayed. Set Digit 1 to the value that holds alarms to the value you want, and then set Digits 2, 3, and 4 to the percentage of full scale at which you want the analog output to freeze. Then press ENTER to execute your selection.

When HOLD is activated and the first digit of this code is 1, 2, or 3, the display alternately flashes between the word HOLD and the VALUE measured by the currently selected sensor. The output is frozen at a value corresponding to a percentage of full scale of the analog output. This percentage is determined by the last three digits of the HOLD code. While in any of the HOLD modes, the Analyzer continues to monitor and display the measurement value. Note that while in this mode, you may clean or replace the sensor and recalibrate the system. As shown in the table below, alarms are held in a fixed state (current, ON, or OFF) whenever Hold is activated. The specific state is determined by the setup code you enter.

MI 611-190 – January 2021 4. Configuration

Digit 1

Output Hold

No Hold

Hold — Alarms Held in

Current State

Hold — Alarms Held in OFF

State

Hold — Alarms Held in ON

State

Digit

Not

Used

HOLD Configuration Codes

Digit 2 Digit 3

Percentage of Analog Output Range

0 to 100%

NOTE

Trying to enter a digit with no assigned function will result in the code Err.

Digit 4

Alarm Configuration (AC1 and AC2)

Two independent, Form C dry alarm contacts, rated at 3A noninductive, 125 V ac/30 V dc are provided with the Analyzer. They are designated as Alarm 1 and Alarm 2.

CAUTION

When the contacts are used at signal levels of less than 20 W, contact function may become unreliable over time due to the formation of an oxide layer on the contacts.

See “Alarm Contact Maintenance” on page 87.

Setting the parameter, AC1, configures Alarm 1 — assigning it to monitor the measurement output of Cell 1 or Cell 2, the average of both cell measurements, the ratio of Cell 1 to Cell 2 measurements, or the difference between the two measurements. The second digit of the code determines whether the alarm output is high or low, active or passive, instrument active or passive, and hold active or passive. The third and fourth digits of the code set the hysteresis of the alarm output, the deadband between set and reset values of alarm activation.

When an alarm condition exists, the display alternately shows alarm status and measurement value, alternating on a 1-second cycle. Wiring information for the alarms may be found in

Chapter 2 of this manual.

NOTE

1. You must reset alarms following any change to FSC because the alarms are set as a percentage of FSC.

2. When power is applied to the instrument, alarm operation is delayed for a time period proportional to the damping time set in CELL1 (Digit 3) or CELL2

(Digit 4). Alarms will remain OFF until the measurement has stabilized.

4. Configuration MI 611-190 – January 2021

When used as a measurement alarm, four configurations are possible:

1. Low passive

2. Low active

3. High passive

4. High active

A low alarm trips on decreasing measurement. A high alarm trips on increasing measurement.

Passive or active (failsafe) configurations are selected by setting Digit 2. When configured as a passive alarm, power is not applied to the relay coil when the alarm is OFF. With an active alarm, however, power is applied to the relay coil when the alarm is OFF, thus providing failsafe operation. In the active (failsafe) configuration, loss of power to the Analyzer causes a change from active to passive relay state, providing contact closure and an indication of a power problem.

Correct wiring of the contacts is necessary for true failsafe operation. (Refer to Chapter 2)

As an alternative to a measurement alarm, one or both alarms may be set up as instrument alarms .

In this “watchdog” state, the alarm can communicate the existence of any diagnostic error in the system. When used as a diagnostic alarm, however, the alarm cannot also be used as a conventional measurement alarm.

When an alarm is configured as a diagnostic error communicator, it will report any system problem. It cannot, however, selectively report a specific type of problem. The hardware/software conditions that can cause a diagnostic (instrument) alarm are:

1. A/D converter error

2. EEPROM checksum error

3. RAM error

4. ROM error

5. Processor task time error (watchdog timer)

In addition to these diagnostics, you may program several temperature and measurement error

limits that, if exceeded, will cause an alarm condition. Refer to Table 7, “Error/Alarm Messages,” on page 85 for a list of error messages and their meanings.

The alarm may also be configured and used as a HOLD alarm. When used as a HOLD alarm, the alarm cannot be used as a conventional measurement alarm. When so configured, the alarm will trigger whenever HOLD is activated. By using this feature, you can notify a control room or alarm device (light, bell, etc.) that the Analyzer is in a HOLD mode instead of a RUN mode. The

ALARM is activated when HOLD is implemented if the first digit in the HOLD code is 1, 2, or

3. A “HOLD” alarm overrides the HOLD state (on, off, current) normally enacted when the unit is placed in HOLD.

MI 611-190 – January 2021 4. Configuration

Setting Alarm Level(s)

NOTE

This procedure is relevant only when the alarms have been configured as measurement high or measurement low alarms. When the alarms are configured as Instrument

(Watchdog) or Hold alarms, alarm level settings have no relevance.

1. Unlock Analyzer (see “Unlocking Analyzer Using Security Code” on page 38).

2. To set Alarm 1, press Alm 1. Then use NEXT to select the digit and Δ to set the desired value for the digit.

3. When you have set all digits, press ENTER.

4. To set Alarm 2, press Alm 2. Then use NEXT to select the digit and Δ to set the desired value for the digit.

5. When you have set all digits, press ENTER.

6. Lock Analyzer (see “Locking Analyzer Using Security Code” on page 38).

NOTE

If use of the alarms is not desired, set Digit 1 of AC1 or AC2 to 0.

Alarm 1 Configuration

Digit 1

Alarm Selection

0 Alarm Not Used (Disables Errors and Parameters, Relay Held

OFF/Passive)

1 Measurement Cell 1

2 Measurement Cell 2

3 Temperature Cell 1

4 Temperature Cell 2

5 Digit Not Used

6 Average Cell 1 and Cell 2

Measurement

7 Ratio (Cell 1/Cell 2) x 100

8 Digit Not Used

9 Difference (Cell 1 - Cell 2)

AC1 Configuration Codes

Digit 2

Configuration

0 Digit Not Used

1 Low/Passive

2 Low/Active

3 High/Passive

4 High/Active

5 Instrument/Passive

6 Instrument/Active

7 Hold/Passive

8 Hold/Active

9 Digit Not Used

Digit 3

Hysteresis

Digit 4

0 to 99% of full scale

NOTE

When Digit 1 of AC1 is set to 0 (i.e., alarm not used), all error messages associated with the alarm are disabled and timer configuration codes (Att1, AFt1, and Adl1) do not appear when stepping through the setup entries.

4. Configuration MI 611-190 – January 2021

Alarm 1 Timers (Att1, AFt1, AdL1)

Three timers are associated with Alarm 1:

♦ Att1 — Alarm 1 Trigger Time

A programmable timer that prevents the alarm from triggering for a user-defined time.

♦ AFt1 — Alarm 1 Feed Time

A programmable timer that holds the alarm ON for a user-defined time once the alarm has been activated — to allow time for chemical/reagent feed.

♦ AdL1 — Alarm 1 Delay Time

A programmable timer that holds the alarm OFF for a user-defined time after the alarm has been held ON by parameter AFt to allow time for mixing or reaction.

Each of these timers is explained in detail in this section. Note, however, that whenever you use any of these timers, the hysteresis function set in parameter AC1 is ignored.

Alarm 1 Trigger Time (Att1) may be used with or without the other alarm timers. Att1 is used only when Alarm 1 is configured as a measurement alarm (high/low) or temperature (high/low). Its purpose is to prevent the alarm from triggering on momentary, non-sustained off-normal conditions. After the timer has timed out, the alarm will activate if the measurement has sustained an off-normal state for the entire trigger time. If the measurement returns to normal at any time,

Att1 resets automatically. The table below defines the configuration codes for Att1.

Att1, AFt1, and AdL1 Configuration Codes

Digits 1 and 3

00 to 99 minutes

Digit 3

0 to 9 tenths of minutes

Digit 4

0 to 9 hundredths of minutes

EXAMPLES:

05.15 means 5 minutes, 9 seconds — 5 minutes + 1 /10 of a minute

(6 seconds) + 5/100ths of a minute (3 seconds)

20.50 means 20 minutes, 30 seconds — 20 minutes +5/10 of a minute

(30 seconds)

Alarm 1 Feed Time (AFt1) and Alarm 1 Delay Time (AdL1) may be used whenever Alarm 1 is configured as a measurement or temperature alarm. Alarm Feed Time (AFt1) works in conjunction with Alarm Delay Time (AdL1) to provide one cycle of pulse-duration on/off control of the Alarm 1 relay (although AFt1 may be used without AdL1). Therefore, these parameters should be set and used together. Note that both take precedence over the hysteresis deadband set in parameter AC1.

When Alarm 1 Feed Time is activated, Alarm 1 remains ON for the length of time set in AFt1 regardless of what the measurement value is — inside or outside of normal range.

MI 611-190 – January 2021 4. Configuration

Alarm 1 Delay Time (AdL1) is activated by entering a value in parameter AdL1. Upon timeout of

AFt1, the alarm is held OFF for this time period. The alarm will not reactivate for the time period set in AdL1 regardless of what the measurement value is. After timeout of AdL1, the 873 reverts to normal run mode. If the instrument has remained in an alarm state for the entire time period

(AFt1 + AdL1), the sequence of AFt1 followed by AdL1 repeats for another cycle without having

to wait another Att1 period (see Figure 12), and so on, until the measurement returns to normal

range and reset the alarm.

The relationships between Att1, AFt1, and AdL1 are illustrated in the following diagram, where

Alarm 1 is configured as a high alarm.

Figure 11. Relationships Between Alarm Timers h i b

SetPoint

Measurement

Alarm Relay

Att1 (5 min.)

AFt1 (15 min) a a b c d f e e h i

OFF

AdL1 (15 min)

0 10 20 30 40

MINUTES

50 60 70

4. Configuration MI 611-190 – January 2021

NOTES: a. Measurement did not remain above set point for timer period set in Att1. Alarm relay remains inactive. Att1 reset when measurement fell below alarm set point.

b. Measurement stays above alarm setpoint continuously for time set by Att1(5 min). After time set in Att1, alarm relay becomes activated (c) for time period (15 min) set by parameter AFt1.

c. Timer Att1 reset when measurement fell below set point (d).

d. Upon timeout of AFt1, timer AdL1 deactivates Alarm 1 relay (f ) for the time period set by this parameter. The alarm remains deactivated even if measurement

(g) exceeds the alarm set point during this period of time.

e. Since the measurement exceeds the set point at the end of AdL1, the timer Att1 resets and the alarm relay remains OFF. If the measurement does not exceed the alarm set point for the entire period Att1 (i), the alarm relay does not activate. If the measurement had exceeded the set point for the entire sum of times (AFt1 +

AdL1), the feed timer (AFt1) would have been reactivated.

A flow diagram for alarm timer logic follows. Note that the flow diagram and the timing diagram apply to both alarms (AC1 and AC2).

MI 611-190 – January 2021

Figure 12. Flow Diagram for Alarm Timer Logic

Start

Measurement

Measurement exceed alarm set point?

Att1

Meas.

above set point continuously for time Att1?

AFt1

AdL1

Did meas.

exceed set point continuously for time

AFt1 + AdL1?

4. Configuration

4. Configuration MI 611-190 – January 2021

Alarm 2 Configuration

Alarm 2 is configured in exactly the same manner as Alarm 1. Refer to AC1 setup instructions.

AC2 Configuration Codes

Digit 3 Digit 4 Digit 1

Alarm Selection

0 Alarm Not Used

(Disables Errors and

Parameters, Relay Held

OFF/Passive)

1 Measurement Cell 1

2 Measurement Cell 2

3 Temperature Cell 1

4 Temperature Cell

5 Digit not Used

6 Average Cell 1 and Cell 2

Measurement

7 Ratio

(Cell 1/Cell 2) x 100

8 Digit not used

9 Difference

(Cell 1 - Cell 2)

Digit 2

Configuration

0 Digit Not Used

1 Low/Passive

2 Low/Active

3 High/Passive

4 High/Active

5 Instrument/Passive

6 Instrument/Active

7 Hold/Passive

8 Hold/Active

9 Digit Not Used

Hysteresis

0 to 99% of full scale

NOTE

When Digit 1 of AC2 is set to 0 (i.e., alarm not used), all error messages associated with the alarm are disabled and timer configuration codes Att2, AFt2, and AdL2 do not appear when stepping through the setup entries.

Alarm 2 Timers (Att2, AFt2, AdL2)

Alarm 2 timers operate in the same manner as Alarm 1 timers. Refer to Alarm 1 timers setup instructions.

Assignment of Analog Outputs (AOUt)

The AOUt parameter defines analog output assignments. Each output signal is linearly proportional to the assigned measurement value (or calculated value such as ratio, average, or difference). Either output may be disabled by setting the appropriate digit to 0. If set to 0, the output is held at 4 mA (or 0 V), all error messages associated with that output are disabled, and the 0% (L01 or L02) and 100% (H01 or H02) configuration codes do not appear in the setup menu. Digit 4 enables or disables local display of an analog error code.

MI 611-190 – January 2021 4. Configuration

AOUt Configuration Codes

Digit 1

Output 1 Assignment

Digit 2

Output 2 Assignment

0 Output Disabled, output held at 4 mA or 0 V, no error message.

1 Measurement Cell 1

2 Measurement Cell 2

Measurement Cell 1

Measurement Cell 2

3 Temperature Cell 1

4 Temperature Cell 2

5 Digit Not Used

6 Average of Cell 1 and Cell 2

Measurements

7 Ratio

(Cell 1/Cell 2) x 100

8 Digit Not Used

9 Difference

(Cell 1 - Cell 2)

Temperature Cell 1

Temperature Cell 2

Digit Not Used

6 Average of Cell 1 and Cell 2

Measurements

7 Ratio

(Cell 1/Cell 2) x 100

Digit Not Used

9 Difference

(Cell 1 - Cell 2)

Digit 3

Digit Not Used

Digit 4

Analog Error Enable

Enabled

1 Disabled

Not Used

NOTE

The analog outputs may swing between the minimum and maximum values immediately after power up, a power interruption, or a reset of the microprocessor.

Scaling of Analog Outputs (H01, L01, H02, L02)

These parameters are used in conjunction with the AOUt code and will not appear in the setup menu when the output assignment is zero.

Both analog outputs may be scaled so as to improve the sensitivity of the analog output in the range of interest. The maximum output span that should be set on the Analyzer is the FSC value.

The minimum span allowed is 10% of the FSC value. Although it is possible to set the Analyzer for a smaller span, a loss of accuracy will result.

You may also wish to reverse the analog signal in some situations. The outputs may be scaled so that the value in L01 (or L02) is higher than the value in H01 (or H02), if desired. No special procedures are required to achieve a reverse acting output.

Analog Output 1 — 100% Value (H01)

This parameter sets the full scale value of Analog Output 1. The value set by this parameter corresponds to 100% of the analog output (20 mA or 10 V).

Analog Output 1 — 0% Value (L01)

This parameter sets the zero scale value of Analog Output 1. The value set by this parameter corresponds to 0% of the analog output (0 mA, 4 mA, or 0 V).

4. Configuration MI 611-190 – January 2021

Analog Output 2 — 100% Value (H02)

This parameter sets the full scale value of Analog Output 2. The value set by this parameter corresponds to 100% of the analog output (20 mA or 10 V).

Analog Output 2 — 0% Value (L02)

This parameter sets the zero scale value of Analog Output 2. The value set by this parameter corresponds to 0% of the analog output (0 mA, 4 mA, or 0 V).

User-Defined Measurement Error Upper Limit Value,

CELL 1 or CELL 2 (UL1, UL2)

These parameters enable you to define an upper measurement limit that, if exceeded, will give an

error message on the display (see “Table 7 on page 85). When used in conjunction with the

configurable alarms, it provides a relay contact output.

The primary use of UL1 or UL2 is as a sensor diagnostic tool. If a problem develops with a sensor that causes the measurement signal to be ridiculously low or high for the process being monitored

(such as a shorted or intermittent connection), an alarm can be triggered. By setting UL1 or UL2 at a value that could never be achieved in a normal process situation, activation of a UL1 or UL2 alarm indicates a severe sensor failure, miscalibration, or a process out-of-control. The upper limit on UL1 or UL2 is 99.99 pH or 9999 mV.

NOTE

UL1 and UL2 values equal to the specified full scale measurement per Sales Order are preconfigured.

Digit 1

Sign

0 to 9

Positive Value

–

Negative Value

UL1 and UL2 Configuration Codes

Digit 2 Digit 3

Upper Limit Value

-0.99 to 99.99 for pH

-999 to 9999 for ORP and ISE

Digit 4

NOTE

To make a minus sign appear on the display for either upper limit value or lower limit value, you must enter a digit other than zero.

MI 611-190 – January 2021 4. Configuration

User-Defined Measurement Error Lower Limit Value,

CELL 1 or CELL 2 (LL1, LL2)

These parameters are similar to the previously described UL parameters, except they allow programming of a lower measurement limit. The lower limit on LL1 or LL2 is -0.99 pH or

-999 mV.

LL1 or LL2 Configuration Codes

Digit 1

Sign

0 to 9

Positive Value

–

Negative Value

Digit 2

Lower Limit Value

Digit 3

-0.99 to 99.99 for pH

-999 to 9999 for ORP and ISE

Digit 4

User-Defined Temperature Error Upper Limit Value,

Both Cells (UtL)

This parameter enables the user to define an upper temperature measurement value that, if

exceeded, will give an error message on the display (Table 7 on page 85). When used in

conjunction with the configurable high or low alarms, this parameter provides a relay contact output.

The UtL function may be used in several ways. First, you may wish to alarm on high process temperature. For example, in a pH measurement that is normally between 80 and 100 ºF, you may wish to set UtL to 120 ºF to indicate a problem with the process temperature. Another use of

UtL is as a sensor diagnostic tool. If the RTD in the pH sensor develops a fault, it may produce erroneous temperature readings at either extreme of the temperature scale.

By setting UtL at a temperature outside of any conceivable process temperature, an alarm will indicate a problem with the pH sensor temperature transducer. The upper limit on UtL is 200ºC or 392ºF.

UtL Configuration Codes

Digit 3 Digit 4 Digit 1 Digit 2

Upper Limit Value

<200ºC or 392ºF Upper Temperature Limit

4. Configuration MI 611-190 – January 2021

User-Defined Temperature Error Lower Limit Value, Both

Cells (LtL)

This parameter is similar to the previously described UtL parameter, except that it allows programming of a lower temperature measurement limit. The lower limit on LtL is –20ºC or -5ºF.

LtL value is preconfigured to 0ºC.

NOTE

To make a minus sign appear on the display, you must enter a digit other than zero.

LtL Configuration Codes

Digit 1

Upper Limit Value

<0 ºC or -5 ºF Lower Temperature Limit

Digit 2 Digit 3 Digit 4

Basic Setup Entries

Basic Setup entries consist of 32 parameters. Because these parameters are calibration oriented, access has two levels of passcode protection. Changes to many of these parameters require that you recalibrate the Analyzer. Do not make any changes unless you have read the explanatory text for each parameter.

The table below lists the basic setup parameter identifiers (in the order in which they appear on the display) and the name of the parameter or value accessed by the identifier. Descriptions of how to set each digit of the display for every parameter are presented in the explanatory text following the table.

Table 4. Basic Setup Entries

Factory Default

Value User Value

Parameter

Identifier

UPH tCF1 tCF2 tCt

PCt tCL1 tCC1 tCH1 bL

FSC1

FSC2

C0 1

C0 2

ISO1

ISO2

Parameters and Value Accessed

Basic Setup Lock Control

Full Scale Value Cell 1

Full Scale Value Cell 2

Compensation Cell 1

Compensation Cell 2

Isopotential Cell 1

Isopotential Cell 2

Offset Voltage

Log of Function

User-entered pH

Temperature Cell Factor - Cell 1

Temperature Cell Factor - Cell 2

Custom Curve Temperature

Custom Curve pH

RTD Low Temp. Electronics Calibration Cell 1

RTD Mid Temp. Electronics Calibration Cell 1

RTD High Temp. Electronics Calibration Cell 1

-0.01

25.00

0000

100.0

150.0

200.0

16.00 pH

20.00 ppm

0000

2010

-0.01

0000

00.00

MI 611-190 – January 2021 4. Configuration

Table 4. Basic Setup Entries (Continued)

Parameter

Identifier dCL* dCH* tout

LCC

SFt**

SOH**

SOL** tCL2 tCC2 tCH2

LCO1

HCO1

LCO2

HCO2

PC*

Parameters and Value Accessed

RTD Low Temp. Electronics Calibration Cell 2

RTD Mid Temp. Electronics Calibration Cell 2

RTD High Temp. Electronics Calibration Cell 2

Analog Out 1 Calibration Low

Analog Out 1 Calibration High

Analog Out 2 Calibration Low

Analog Out 2 Calibration High

Probe Calibration

Drive Calibration Low

Drive Calibration High

Timeout Time

Lock Code Change

Software Version Number

Sales Order High

Sales Order Low

Factory Default

Value

100.0

150.0

200.0

00.00

100.0

00.00

100.0

0000

N/A

0010

0800

* These parameters are factory calibrated to appropriate values. Do not

alter these parameters in the field.

** These parameters are factory preset for informational purposes only. They cannot be changed in the field.

User Value

Unlocking Basic Setup Entries (bL)

To change any of the Basic Setup Entries, use the following procedure.

1. Unlock Analyzer at the first security level (see “Unlocking Analyzer Using Security

Code” on page 38).

2. Press SHIFT + SETUP. Release both keys.

3. Press NEXT repeatedly until bL is displayed.

4. Press ENTER. LOC appears on the display.

5. Press NEXT.

6. Use NEXT and Δ until security code is displayed (0800 from factory).

7. Press ENTER. ULOC appears on the display.

8. When display returns to bL, press NEXT one or more times until parameter to be changed appears on the display.

9. Press ENTER.

10. Use NEXT and Δ until the desired value is displayed.

11. Press ENTER.

12. When the display defaults (times out) to the current measurement value, the Analyzer is automatically locked at the second level (bL) of security.

13. Lock Analyzer (see “Locking Analyzer Using Security Code” on page 38).

4. Configuration MI 611-190 – January 2021 bL Configuration Codes

Digit 1

Basic Setup Enable

Digit 2 Digit 3

4-digit LOCK # (enables changing of setup values for entries following a bL entry.

Basic Lock is reactivated automatically when SETUP is exited via a default timeout.)

Digit 4

Selecting and Changing the Full Scale Range (FSC1 and FSC2)

The FSC1 and FSC2 parameters permit you to select the mode of operation for each channel of the 873DPX — pH, ORP, or one of several ISE ranges. The FSC range choices are listed in the following table.

FSC1 and FSC2Configuration Codes

Digit 2 Digit 3 Digit 4 Digit 1

Units of Measurement

16.00 — pH

1400 — mV

2.000 — ppm

20.00 — ppm

200.0 — ppm

2000 — ppm

FSC1 is the full scale range for Sensor 1 and FSC2 is the full scale range for Sensor 2. You can use any combination of FSC1 and FSC2 codes. Note, however, that pH-corrected ISE measurements require that Sensor 1 be a pH sensor (i.e., FSC1 = 16.00 pH) and Sensor 2 be the appropriate ISE

(i.e., FSC2 = 2, 20, 200, or 2000 ppm).

NOTE

1. Altering the FSC range via the Keypad will require that you bench calibrate the unit before use.

2. Pressing ENTER in FSC mode (even if range was not changed) will require the unit to be bench calibrated before use. If the range is set at the FSC you require, allow unit to time out. Do not press ENTER.

After changing FSC, Configuration Setup Entries should be checked and altered if necessary. The the FSC value per Sales Order is preconfigured.

The procedure to change FSC is as follows:

1. Unlock Analyzer (see Unlocking Analyzer Using Security Code ).

2. Press SHIFT + SETUP. Release both keys.

3. Press NEXT several times until the code bL (Basic Setup Lock) is displayed.

4. Press ENTER, then use NEXT and Δ until the personal security code is displayed

(0800 from factory).

5. Press ENTER.

6. When the display returns to bL, press NEXT. The code FSC1 (Full Scale Range

Change) will be displayed. If FSC2 is desired, press NEXT again.

MI 611-190 – January 2021 4. Configuration

7. Press ENTER. The present full scale range will be displayed. If this is your desired

FSC, allow unit to time out. DO NOT PRESS ENTER. Entering any FSC at this point will cause Er4 to flash on the display. A bench calibration then must be performed.

8. Press Δ until the desired range is displayed.

9. Press ENTER.

10. Lock Analyzer (see Locking Analyzer Using Security Code ).

NOTE

Calibration is required after full scale range is changed. Error code Er4 will flash until

calibration is accomplished. Refer to the Calibration section in Chapter 5

Temperature Compensation (CO1 and CO2)

CO1 and CO2 are used to select the type of temperature compensation to be applied to the measurement. Temperature compensation is applied to pH and ISE measurements only and is not available for ORP measurements. If FSC1 (or FSC2) is configured for ORP measurement, the entries in C01 (or C02) are ignored. CO1 sets the compensation for Sensor 1 and CO2 set the compensation for Sensor 2.

pH Compensation Selection (Digits 1 and 2)

Digit 1 is used for choosing the type of electrode — glass, antimony, or variable isopotential. If glass or antimony is chosen (0 or 1), the isopotential point of the electrode is fixed at 7 pH for glass and at 1 pH for antimony. You may vary the isopotential point by selecting 2 for this digit and setting the ISO1 (or ISO2) configuration code to the desired isopotential. See the section

on“Isopotential Points (ISO1 and ISO2)” on page 58 for a more detailed discussion.

Digit 2 is used for choosing the type of temperature compensation applied to the measurement.

Choosing 0 applies the standard Nernstian compensation, which is appropriate for most pH applications. With this type of compensation, the Analyzer uses the temperature reading from the process (or a manually entered temperature) to adjust the Nernst slope factor and, hence, the pH value. The pH displayed is the actual pH of the process at the temperature of measurement . This type of temperature compensation adjusts for temperature effects on the electrodes, but does not correct for the fact that the actual solution pH may vary with temperature. Choosing 1 not only applies the standard Nernstian compensation, but also applies an additional correction for water samples with 1 ppm ammonia. This correction provides a pH value referenced to 25ºC to compensate for the variations of solution pH due to the presence of ammonia. Choosing 9 applies a custom temperature compensation curve that corrects for temperature-related variations in solution pH. Custom curves, which are application dependent, require you to determine and enter process-specific pH versus temperature data. See Custom Temperature Compensation (tCt) for details.

Digits 1 and 2 are ignored if the corresponding FSC is set to ORP or ISE.

4. Configuration MI 611-190 – January 2021

Digit 1 Digit 2

Electrode Type pH Compensation

0 Glass (fixed isopotential = pH 7)

2 ISE, variable potential selected by ISO1

0 Standard Nernstian

Compensation

1 Antimony (fixed isopotential

= pH 1)

1 Ammonia

Digits 2 - 8

Not Used

ISE Compensation Selection (Digits 3 and 4)

Digit 3 sets the ion polarity. If the ion to be measured is a positive ion (such as sodium, potassium, calcium, or silver), Digit 3 should be set to zero. If it is a negative ion (such as fluoride, chloride, cyanide, or bromide), Digit 3 should be set to 1.

Digit 4 is used to set the type of compensation applied to the measurement. As with pH, setting the digit to 0 provides the standard Nernstian temperature compensation. Choosing 1, 2, or 3 in

CO2 only, allows you to correct the ISE measurement for acid, base, or selectivity coefficient errors. For this type of correction, a pH sensor must be used as Sensor 1 and an ISE used for

Sensor 2. The 873DPX will use the pH reading from Sensor 1 to make the appropriate correction on a ISE reading from Sensor 2. You must also enter the appropriate constant in the PF

configuration code (see “Log of Function (PF)” on page 59

for details.). If a pH sensor is not used with the 873DPX, this type of correction can still be performed by using a manually entered constant pH value in the UPH configuration code and selecting either a 4, 5, or 6 (for Manual

Acid, Base, or Selectivity Coefficient). The 873DPX performs these corrections using the UPH

value as the pH of the process. (Refer to “User Entered pH (UPH)” on page 60 for details.)

Finally, custom temperature and ppm curves may be used to compensate the ISE measurement by selecting 7 (custom temperature and ppm curves), 8 (custom ppm only), or 9 (custom

temperature only). Refer to “Generating and Entering Custom Curves in the 873DPX” on page 64 for details.

Digits 3 and 4 are ignored if the corresponding FSC is set to ORP or pH.

CO1 Configuration Codes

Digits 3-9

Not Used

9 Custom Temperature

Compensation

Digit 3

Ion Polarity

0 Positive Ion

1 Negative Ion

Digits 2-9

Not Used

Digit 4

ISE Compensation

0 Standard Nernstian

Compensation

1 Not Used

4 Manual Acid

5 Manual Base

6 Manual Selectivity

Coefficient

7 Custom Temperature and ppm Compensation

8 Custom ppm

Compensation Only

9 Custom Temperature

Compensation Only

MI 611-190 – January 2021 4. Configuration

CO2 Configuration Codes

Digit 1 Digit 2

Electrode Type pH Compensation

0 Glass (fixed isopotential = pH 7)

1 Antimony (fixed isopotential = pH 1)

2 ISE, variable potential selected by ISO2

3 Digits 3-9

Not Used

0 Standard Nernstian

Compensation

1 Ammonia

2 Digits 2-8

Not Used

Digit 3

Ion Polarity

0 Positive Ion

1 Negative Ion

2 Digits 2-9

Not Used

9 Custom Temperature

Compensation

Digit 4

ISE Compensation

0 Standard Nernstian

Compensation

1 Acid

2 Base

3 Selectivity Coefficient

4 Manual Acid

5 Manual Base

6 Manual Selectivity

Coefficient

7 Custom Temperature and ppm Compensation

8 Custom ppm

Compensation Only

9 Custom Temperature

Compensation Only

Isopotential Points (ISO1 and ISO2)

These parameters set the isopotential point for Sensor 1 (ISO1) and Sensor 2 (ISO2). When the corresponding FSC is configured for ISE measurement and CO1 and CO2 have been set to variable isopotential, this code allows you to enter an isopotential point (a millivolt value that reads the same at every temperature) of an ISE. This value is also called the isothermal point. The code can be set anywhere between -999 and +1000 mV. Unless the isopotential point of an ISE is known or has been experimentally determined, this value should be left at 0 mV. When the FSC is configured for pH measurement, this code allows you to adjust the isopotential pH of the sensor if CO1 (or CO2) is configured for a pH electrode with an adjustable isopotential.

ISO1 and ISO2 Configuration Codes

Digit 3 Digit 4 Digit 1

Isopotential Temperature Compensation

-999 to +1000 mV

-9.99 to 99.99 pH

Digit 2

4. Configuration MI 611-190 – January 2021

Offset Voltage (OF)

The 873DPX configured for ISE measurement has a 300 mV span with range limits of -999 to

+1000 mV. This 300 mV span can be shifted anywhere the range. The offset voltage, set by the

OF parameter, determines where that span is to be centered. If, for example, you selected an OF of 700, the 300 mV span of the instrument would be 550 to 850 mV. The default value of OF is

0 mV, providing a range of -150 mV to +150 mV.

OF Configuration Codes

Digit 1 Digit 2 Digit 3

Offset voltage to center 300 mV ISE range

Digit 4

-850 to +850 mV

Log of Function (PF)

This parameter is used for entering the constant needed for calculation of acid, base, and selectivity coefficient compensation of ISE measurements.

Acid Compensation

Acid compensation is used when the ion to be measured can complex with hydrogen ions. For example, fluoride ions in acidic solutions can complex with hydrogen ions to form HF or HF

These complexes will not be detected by the fluoride electrode. By measuring the pH of the solution or by using a manually entered pH value in the UPH parameter, however, the 873DPX can calculate the proportion of fluoride ions that are complexed with hydrogen, thus providing a means for correcting this error. This calculation requires a constant (pKa) to be entered in the PF parameter. You can obtain the pKa from standard literature or determine it experimentally

[pKa = -log(Ka)].

Base Compensation

Base compensation is used when the ion to be measured can complex with hydroxide ions and not be detected by the ISE. As with acid correction, the 873DPX can compensate for this effect by measuring solution pH or by using a manually entered pH value from the UPH parameter, and then calculating the proportion of ions complexed with hydroxide. This calculation requires a constant (pKb) to be entered in the PF parameter. You can obtain the pKb from standard literature or determine it experimentally [pKb = -log(Kb) = -log(14 - Ka)].

Selectivity Coefficient Compensation

Selectivity coefficient compensation is used when an interfering ion can cause errors in an ISE measurement. For example, a fluoride electrode is also sensitive to the presence of hydroxide ions.

In basic solutions, a fluoride sensor will react to hydroxide ions as well as fluoride ions, giving an abnormally high reading. By measuring the pH of the solution or by using a manually entered pH value from the UPH parameter, the 873DPX can compensate for the interfering effect of hydroxide ions. This calculation requires a constant to be entered in the PF parameter. The PF constant is determined experimentally.

MI 611-190 – January 2021 4. Configuration

Digit 1

PF Configuration Codes

Digit 2 Digit 3

Constant for Compensation of ISE

Digit 4

00.00 to 99.99

User Entered pH (UPH)

This parameter is used with manual acid, base, or selectivity coefficient compensation of an ISE measurement. Instead of correcting an ISE measurement for a pH value obtained from a pH sensor, the 873DPX can use a manually entered pH value from this parameter. If you want to use acid, base, or selectivity coefficient correction of an ISE measurement and you know the pH of your process, you may enter it in this parameter and then select manual acid, manual base, or

manual selectivity coefficient compensation using CO1 or CO2. (See “Temperature

Compensation (CO1 and CO2)” on page 56

for details.) The 873DPX will perform the appropriate correction using the UPH value instead of an actual pH measurement value.

NOTE

To use this parameter, the pH of the process must be known and must also remain stable.

Digit 1

UPH Configuration Codes

Digit 2 Digit 3

User-entered pH

Digit 4

0000 to 16.00

Temperature Cell Factors (tCF1, tCF2)

These parameters set the temperature correction factors for Sensors 1 and 2. These factors are

used to compensate for extended cable length. Refer to “Temperature Cell Factor” on page 78 for

more detail.

RTD Temperature Calibration (tCL1, tCC1, tCH1, tCL2, tCC2, tCH2)

RTD temperature electronics are factory calibrated to compensate for calibration errors caused by thermal effects in the electronic equipment. This calibration aligns the electronics to the theoretical temperature transducer values at 25ºC. It should not be necessary to perform these procedures in the field unless:

1. You suspect a problem with the temperature calibration.

2. You wish to verify temperature electronics calibration.

4. Configuration MI 611-190 – January 2021

For Sensor 1, use tCL1, tCC1, and tCH1. For Sensor 2, use tCL2, tCC2, and tCH2.

To perform this calibration, execute the following procedure:

1. Connect a 100-ohm precision resistor between sensor input terminals 1 and 2.

2. Unlock Analyzer using security code.

3. Press SHIFT + SETUP. Release both keys.

4. Press NEXT several times until the code bL (Basic Lock Setup) is displayed.

5. Press ENTER, and then use NEXT and Δ until the personal security code is displayed (0800 from factory).

6. Press ENTER.

7. When display returns to bL , press NEXT until tCL1 (or tCL2) is displayed. Press

ENTER.

NOTE

Holding the SHIFT key will keep the display from timing out.

8. Display will show 100.0 ohms. Press SHIFT and hold for 20 seconds, then press

ENTER.

9. Repeat Steps 1 - 8 using tCC1 (or tCC2) and a 150-ohm precision resistor.

10. Repeat Steps 1 - 8 using tCH1 (or tCH2) and a 200-ohm precision resistor.

Changing the Analog Output

To change one or both of the analog outputs from those ordered with the Analyzer, you must reposition jumpers and recalibrate the instrument.

To Reposition Jumpers

1. Remove power from the instrument.

2. Remove four front panel screws holding the display panel in place. Remove rear cover.

Disconnect the green earth (ground) cable and feed wire from the sensors and power connection through seals to allow free movement of the circuit boards.

CAUTION

Since the four screws are self-tapping, they have a limited number of taps. Do not remove and tighten these screws repeatedly.

3. To access the upper circuit board designated AS700DZ-02, slide the circuit assembly out the front of the housing.

4. Refer to Figure 13 on page 62 to identify jumper locations.

5. Use the following table to determine appropriate jumper positions.

Output

4 - 20 mA

0 - 20 mA

0 - 10 V dc

2 - 3

1 - 2

2 - 3

1 - 2

2 - 3

1 - 2

J10

2 - 3

1 - 2

MI 611-190 – January 2021 4. Configuration

6. Move each jumper to the appropriate position.

7. Replace board assembly inside unit.

8. Replace cover. Use Loctite (Part No. S0106ML) and Lubriplate (Part No. X0114AT) on threads of screws of all metal enclosures.

9. Perform an analog output calibration, using procedures described in the next section.

10. Make appropriate changes to the Analyzer identification label.

Figure 13. Jumpers for Changing Analog Outputs

J10

Output

4 -20 mA

0 - 20 mA

0 -10 Vdc

2 - 3

1 - 2

2 - 3

1 - 2

2 - 3

1 - 2

J10

2 - 3

1 - 2

NOTE: JUMPERS J6 AND J10

CORRESPOND TO ANALOG

OUTPUT #1. JUMPERS J5 AND

J7 CORRESPOND TO ANALOG

OUTPUT #2.

4. Configuration MI 611-190 – January 2021

Analog Output Calibration (LCO1, HCO1, LCO2, HCO2)

These parameters set the minimum or maximum values of the analog outputs as a percentage of full scale value (10.0 V or 20.0mA).

Since the instrument was calibrated at the factory, it should not require recalibration unless the type of output has been changed. To calibrate Analog Output 1, execute the following procedure:

1. Connect an ammeter/voltmeter to the analog output terminals.

2. Unlock the Analyzer using the security code.

3. Press SHIFT + SETUP. Release both keys.

4. Press NEXT several times until the code bL is displayed. Press ENTER.

5. Use NEXT and Δ until the personal security code is displayed (0800 from the factory). Press ENTER.

6. When display returns to bL, press NEXT until LC01 is displayed. Press ENTER.

7. Calculate the low % input required by using the following formula:

% = (Observed Reading - Desired Reading)/ (Analog High) x 100

8. Use NEXT and Δ until the calculated value from Step 7 is displayed. When finished, press ENTER.

NOTE

Iteration of the above procedure may be required. Repeat Steps 7 and 8 until

Observed Value is equal to the Desired Value.

9. When the display returns to LCO1, press NEXT once to display HCO1. Press

ENTER.

10. Calculate the high % input required, using the following formula:

% = [(Observed Reading/Desired Reading) ] x 100

11. Use NEXT and Δ until the calculated value from Step 10 is displayed. When finished, press ENTER.

NOTE

Iteration of the above procedure may be required. Repeat Steps 10 and 11 until

Observed Value equals Desired Value.

12. To calibrate Analog Output 2, repeat the above procedure substituting LCO2 and

HCO2 for LCO1 and HCO1.

MI 611-190 – January 2021 4. Configuration

Generating and Entering Custom Curves in the 873DPX

Custom temperature compensation and process-specific concentration data may be entered into

873DPX Analyzers via the Curve Generation Program . This section explains how to generate and enter custom curve data into your 873DPX Analyzer. To use the data after entering it, you must set up parameters CO1 and CO2.

Custom Temperature Compensation Curve (tCt)

Figure 14. Flow Chart for Custom Temperature Compensation Curve

Determine custom temperature vs. pH (or ppm) data unlock Cell 1

or 2

Temp

°C or °F

FSC

(units) tCt

1. User-supplied process-specific compensation data must be generated or extracted from literature in advance of entering it into the 873DPX. This data must consist of temperature (ºF or ºC) vs. pH (or ppm) data for a particular concentration of the process (control point suggested). The temperatures should include all temperatures in the target process temperature range and be entered in ascending order. It is suggested that you plot the data graphically in preparing it for entry into the

873DPX.

EXAMPLE:

The control point of a process is 10.0 pH. The process typically runs at ambient temperatures that fall in the range of 0 to 50ºC. A sufficient grab sample of the process is taken and protected from atmosphere. Using a pH (or ISE) sensor and the 873DPX Analyzer set for standard Nernstian temperature compensation (CO1 or CO2 = 0000), pH vs. temperature

data is generated. The data results are shown in Figure 15.

2. The user-supplied, process-specific compensation data must be reduced to fewer than

25 pairs, using the following general guidelines: a. Enter the data into the Analyzer with increasing values of temperature, using the current temperature scale of the unit. b. A maximum or minimum temperature difference between successive temperature points is not required and the intervals do not have to be equally spaced.

It is suggested that in a linear region you choose two or three points and that in a region where an exponential (curved) relationship exists, you use more data points.

c. The maximum number of data pairs you may enter is 25.

3. The process-specific reference temperature must be determined.This is the optimum temperature at which your process runs and is the temperature to which you wish all values corrected. In the example, the reference temperature is 25ºC.

4. Configuration MI 611-190 – January 2021

Item

Number of pairs

Reference Temperature

First Temperature

First pH (or ppm) value

Second temperature

Second pH (or ppm) value

Third temperature

Third pH (or ppm) value

Fourth temperature

Fourth pH (or ppm) value

Fifth temperature

Fifth pH (or ppm) value

Sixth temperature

Sixth pH (or ppm) value

Seventh temperature

Seventh pH (or ppm) value

Eighth temperature

Eighth pH (or ppm) value

Ninth temperature

Ninth pH (or ppm) value

Tenth temperature

4. Access Setup Code tCt.

a. The first number to enter is the number of pairs of temperature/pH (or ppm) data you wish to enter. Press ENTER.

b. The second number to enter is the reference temperature, using the temperature units convention set in Step 2. No temperature units will be displayed. Press

ENTER.

c. The third number to enter is the first temperature value.

d. Use NEXT and Δ to display the corresponding pH (or ppm) value from your table. The legend should display the correct units of measurement. (The legend and decimal point display will show the units of the currently active probe

“FSC.”) Press ENTER.

e. Repeat Steps 4c and 4d in sequence. To avoid a timeout while you make the entries, press and hold SHIFT. If a timeout does occur, however, you must restart from Step 4a. However, as all data entered up to the timeout will remain, simply step through the data points via ENTER until you reach the timeout point. The continued example below illustrates the procedure.

EXAMPLE (continued from previous page):

Enter the following numbers into the tCt parameter in the sequence shown.

Value Entered

25.0

0.0

10.32 pH

5.0

10.25 pH

10.0

10.18 pH

15.0

10.12 pH

20.0

10.06 pH

25.0

10.01 pH

30.0

9.97 pH

35.0

9.93 pH

40.0

9.89 pH

45.0

Action

Press ENTER.

MI 611-190 – January 2021 4. Configuration

Tenth pH (or ppm) value

Item

Eleventh temperature

Eleventh pH (or ppm) value

Value Entered

9.86 pH

50.0

9.83 pH

Action

Press ENTER.

5. This completes entry of custom temperature data. To use the information for temperature correction of pH or ppm data, set up CO1 or CO2 to use custom temperature compensation data.

10.4

10.3

10.2

10.1

Figure 15. Example of pH vs. Temperature Custom Curve

DATA DERIVED EXPERIMENTALLY

OR FROM LITERATURE

TEMP

(

°C) pH

10.32

10.25

10.18

10.12

10.06

10.01

9.97

9.93

9.89

9.86

9.83

9.9

9.8

0 pH READING AFTER TCT COMPENSATION

IS APPLIED

5 10 15 20 25 30 35

TEMPERATURE °C

40 45 55 60

Custom PPM Curve (PCt)

Determine custom ppm data

(Actual vs observed)

Figure 16. Flow Chart for Custom Percent Concentration unlock

Cell 1 or 2

FSC

(ppm)

CO1

CO2

PCt

4. Configuration MI 611-190 – January 2021

1. User-supplied process ppm data must be generated before you enter it into the

873DPX Analyzer. The data must consist of actual ppm values versus observed ppm values. The concentrations should include the entire range that the process may experience. You must enter the actual ppm values in ascending order and not change the direction of slope of the data. In preparing the data, it is helpful to plot the data as a graph as well as a table.

EXAMPLE:

A series of solutions with known fluoride concentrations ranging from 0.3 ppm to 10 ppm are prepared. Using a fluoride sensor and the 873DPX with standard Nernstian compensation

(CO1 or CO2 set to xx10), a set of observed ppm readings versus actual ppm concentrations

is collected. Results are shown in Figure 17, with ppm concentrations plotted against

millivolts. The graph is plotted on a semilogarithmic scale to illustrate the linear relationship between mV and ppm decades. Note that in the range below 1 ppm actual ppm readings deviate from an ideal linear response. Entering the observed ppm vs. actual ppm data into tCt

allows the 873DPX to correct this nonlinearity. The data results are shown in Figure 17.

2. The user-supplied ppm data must be reduced to 25 or fewer pairs, using the following guidelines: a. The data should be presented and entered into the Analyzer with increasing ppm values.

b. The slope of the data must not change sign.

c. A maximum or minimum ppm difference between data points is not required and the intervals between points do not have to be evenly spaced. In a linear region, two or three points is sufficient. In a region where an exponential or curved relationship exists, more data points should be entered.

d. The maximum number of data pairs is 25.

3. Custom temperature compensation tCt should be entered first. Refer to the preceding section for details. Unlock bL. Press NEXT repeatedly until PCt appears on the display. Then press ENTER.

a. First, enter the number of data pairs you plan to enter. Press ENTER.

b. Next, enter the first observed ppm value. Use NEXT and Δ to display the first observed ppm value in your table. The display should show the ppm units legend.

Press ENTER.

c. Use NEXT and Δ to display the corresponding actual ppm value from your table.

Press ENTER. The Cel2 legend should be displayed.

d. Repeat Steps 3b and 3c in sequence. To avoid a timeout while entering data, press and hold SHIFT. If a timeout does occur, however, restart the procedure from

Step 3a.

MI 611-190 – January 2021 4. Configuration

Figure 17. Custom ppm Data

-30

-20

-10 mV

0.1

ACTUAL PPM

OBSERVED PPM

1.0

ppm

10.0

EXAMPLE:

Enter data into the PCt parameter in the following sequence:

Item

Number of pairs

Fist observed ppm reading

First actual ppm value

Second observed ppm reading

Second actual ppm value

Next observed ppm reading

Next actual ppm value

Next observed ppm reading

Next actual ppm value

Next observed ppm reading

Next actual ppm value

Next observed ppm reading

Next actual ppm value

Next observed ppm reading

Next actual ppm value

Final observed ppm reading

Final actual ppm value

Value Entered (legend)

0.1 (ppm)

0.03 (Cel2)

0.13(ppm)

0.05 (Cel2)

0.18 (ppm)

0.1 (Cel2)

0.29 (ppm)

0.2 (Cel2)

0.37 (ppm)

0.3 (Cel2)

0.77 (ppm)

0.7 (Cel2)

1 (ppm)

1 (Cel2)

10 (ppm)

10 (Cel2)

Action

Press ENTER.

4. Configuration MI 611-190 – January 2021

4. This completes the custom ppm curve entry. To use this information for correcting ppm concentration data, set up CO1 (or CO2) to correspond to xxx7 or xxx8. Refer

to “Temperature Compensation (CO1 and CO2)” on page 56 in this chapter.

Timeout Time Adjustment

When the 873DPX is in the SETUP mode and no key is pressed within a 10-second period, the

Analyzer automatically exits from SETUP and defaults to OPERATE mode. This feature is called timing out . The timeout time is factory-set at 10 seconds. You may, however, change the time to any value between 3 and 99 seconds by setting the tOut parameter.

tOut Configuration Code

Digit 1 Digit 2 Digit 3

Adjustable Timeout Time

Digit 4

3 to 99 seconds

Instrument Lock Code Change Control (LCC)

This parameter permits you to change the security code to another 4-digit code.

To enter a new code, execute the following procedure:

NOTE

If you have forgotten the existing security code, you must contact Global Customer

Support for instructions on how to enter a new one.

1. Leave power on.

2. Press LOCK. Display will show either Loc or uLoc.

3. If uLoc is displayed, proceed to Step 4.

4. If Loc is displayed, unlock the Analyzer. Display will read uLoc.

5. Press SHIFT + SETUP. Release both keys.

6. Press NEXT several times until the code bL (Basic Setup Lock) is displayed. Press

ENTER.

7. Then use NEXT and Δ until existing security code is displayed (0800 from factory).

8. Press ENTER.

9. When display returns to bL, press NEXT several times until the code LCC (Lock

Code Change) is displayed.

10. Press ENTER, then use the NEXT and increment ( Δ ) keys until the desired new security code is displayed.

11. Press ENTER. The new code will now be required for all future entries.

12. Lock the Analyzer using the standard procedure.

MI 611-190 – January 2021

Digit 1

0000 to 9999

LCC Configuration Codes

Digit 2 Digit 3

4-digit Lock Code

4. Configuration

Digit 4

5. Calibration

The Calibration section is divided into two main parts:

1. Electronic Bench Calibration

2. Calibration of a Sensor

The description of Electronic Bench Calibration contains the procedures for calibrating the

873DPX Analyzer with theoretical mV inputs.

The description of Calibration of a Sensor provides calibration procedures and standardization techniques for individual sensors and solutions. These additional procedures are recommended for verifying individual electrode functions and for achieving best system accuracy.

The section titled Temperature Cell Factor fine tunes the RTD temperature signal to agree with actual temperature. This procedure must be followed if you use long cable lengths.

CAUTION

Do not remove the four front panel screws and the electronics package for calibration.

The self-tapping screws have a limited number of taps and will not function properly with repeated use.

Electronic Bench Calibration

The procedure for calibrating 873 analyzers with theoretical mV inputs is as follows.

Figure 18. Flow Chart for Electronic Bench Calibration

Temp FSC CO1 CAL LO CAL HI

NOTE

All 873 analyzers are calibrated and configured before shipment. You may verify calibration by feeding mV values into the unit. Verification of proper operation of the

873 electronics can be an aid in troubleshooting a problem installation. If the unit operates properly in this calibration, it may be ruled functional in the installation. If the FSC was changed from the factory configured range, the analyzer should be bench calibrated. Do not press ENTER if you are checking the calibration.

Note that once a sensor connected to the 873DPX is calibrated in pH buffers or standard solutions, the theoretical values entered during the electronic bench calibration procedure are removed.

MI 611-190 – January 2021 5. Calibration

Equipment Required for Calibration

♦ Precision millivolt standard (0 to 1000 mV dc ±.1%)

♦ 110-ohm precision resistor for temperature simulation

Procedure

The procedure for performing bench calibration is:

1. Disconnect all sensor leads from analyzer.

2. Unlock analyzer (see ).

3. Check the temperature circuit calibration a. Connect a 110-ohm resistor across sensor input terminals 1 and 2. b. Press TEMP. The unit should then be in the Automatic Temperature mode and no decimal should be visible after the C or F legend. If there is a decimal after the

C or F legend, remove it. To do so, press Δ once after pressing TEMP; then press

ENTER. c. Reset tCF1 to 25.00 (the theoretical temperature transducer value). d. Press TEMP. The display should read approximately 25ºC or 77ºF. If the display does not read either of these values, reset the temperature electronics for recalibration. e. The unit should now be put into manual temperature mode. There should be a decimal to the right of the legend. Press TEMP. Press Δ one or more times until the display reads 25ºC. Press ENTER.

f. Use NEXT + Δ until the display reads (2)5.00 ºC. The first digit 2 will not be displayed. Press ENTER.

4. Reset the Full Scale value of the analyzer. Refer to . Even if the existing Full Scale

Value is the desired value, it is important to reenter the same value. When the FSC value is entered, error code Er4 should begin to flash on the display.

NOTE

1. If an Error Code of higher priority is present, it will preempt the Er4 message.

2. Holding the Shift key between entries will prevent the analyzer from timing out and leaving the Setup entries.

5. Check and adjust the damping factor of the unit. Refer to CELL configuration in

Chapter 4. Set CELL to read “xx00”. The unit should have no damping and should use the standard Nernstian compensation during calibration (CO1 or CO2 = X0X0).

5. Calibration MI 611-190 – January 2021

6. Zero and Span Calibration a. Connect a mV power supply to sensor input terminals — positive to 3 and negative to 4 and 5.

b. Connect a jumper between sensor input terminals 4 and 5. c. Adjust the mV supply to the desired low value as determined by the formula in

Table 5. Wait at least 15 seconds for the electronics to stabilize.*

d. Press SHIFT and while holding, press CAL LO. Release fingers from both keys.

Use NEXT and Δ until the display reads the desired low value. Press ENTER.

e. Calculate the mV input required for Calibrate High Value. The CAL HI value should fall within the range of the FSC that has been chosen. *(For ORP, see note.)

NOTE

* The Er4 code should stop flashing. An error of lower priority may begin to flash. See

Section 6

f. Input mV value corresponding to calculated CAL HI value. Wait at least

15 seconds for the electronics to stabilize.

g. Press SHIFT and while holding, press CAL HI. Release fingers from both keys.

Use NEXT and Δ until the display reads desired CAL HI value. Press ENTER.

7. Lock analyzer (see ).

8. This completes the Standard Electronics Bench Calibration procedure.s

Table 5. mV Supply Formulas

Measurement Mode mV Power Supply Formula

Glass pH

Antimony pH

ORP ppm (ISE)

Examples

(pH–7) x –59.16

(pH–1) x –55 pH 0: (0 – 7) x –59.16 = +414.1 mV pH 14 : (14 – 7) x –59.16 = –414.1 mV pH 0: (0 – 1) x –55.00 = +55.0 mV pH 7: (7 – 1) x –55.00 = –330.0 mV

(mV) *

58/n x log[ppm/ppm(known)]

+ mV known**

Input absolute mV

Fluoride (F

−

)

Charge is negative and monovalent (n= -1)

Known:

1 ppm F

−

= 0 mV

2 ppm: 58/(-1) x log[2/1] + 0 = -17.5 mV

20 ppm: 58/(-1) x log [20/1] + 0 = -75.5 mV

NOTE

*ORP: Do not exceed an input voltage of 1700 mV. Suggested ORP calibration range is ±900 mV. The lower limit is –999 mV, the upper limit is 1400 mV. Values up to

1700 mV can be displayed on the unit. Above this value, 9999 is displayed. Input voltages exceeding 2000 mV will cause an Er 1 to occur.

MI 611-190 – January 2021 5. Calibration

NOTE

**ISE: Electronic calibration of ISEs requires prior knowledge of the charge and valence of the ion (n) and the mV response of the ISE at a given concentration [ppm

(known) and mV known]. This data should be available in the literature provided by the electrode manufacturer and may be expressed in a graph such as the example for a

fluoride electrode shown in Figure 19. If the calculated voltages do not fall within the

-150 to +150 mV span of the 873DPX, it may be necessary to change the offset voltage (OF) to place the 300 mV span in the appropriate place within the range.

10.0

5.0

3.0

1.5

1.0

0.5

0.3

Figure 19. Fluoride Electrode Response as Function of Temperature

12.5°C (54.5°F)

0°C (32°F)

TYPICAL

FLUORIDE

CONTENT

25°C

77°F

0.1

+60 +40 +20 mV

0 -20 -40 -60

5. Calibration MI 611-190 – January 2021

Calibration Of A Sensor

General Information

In many circumstances, a sensor used on an analyzer that has been bench calibrated may provide sufficient accuracy to the user. The electronic bench calibration establishes an approximate relationship between pH or ppm values displayed and expected mV output from a sensor. In such cases, you may connect the sensor to the analyzer and use it without further calibration.

A single point standardization using one buffer or standard solution, preferably near the process measurement value, is often suitable for routine measurements. For the best possible system accuracy, use a two point standardization, preferably bracketing the process control point. You may also extract a sample from the process stream (i.e., a grab sample), perform a laboratory analysis, and calibrate the analyzer with the results of the analysis. This is also a convenient way to perform sample calibration as it allows the sensor to remain installed in the process during standardization.

The electronic bench calibration is described earlier in this chapter. The other three commonly used techniques are discussed in the following sections. In addition, a correction should be made to correct temperature measurements that may differ from actual values (such as when sensor cable length exceeds 50 feet). These procedures should be performed prior to sensor standardization in buffers.

In all cases, these general guidelines should be observed:

1. Clean sensors thoroughly before standardization.

2. Use fresh pH buffers or standard solutions.

3. Allow enough time for sensor and temperature-compensator to reach thermal equilibrium. The temperature display should indicate the correct temperature of the buffer.

4. For pH standardization, use the correct pH value of the buffer during standardization

— pH buffers have different values at different temperatures.

5. Allow sufficient time to reach thermal and chemical equilibrium.

6. Sensors must be properly grounded in solution during the standardization. The black threads of the Model 871A sensors must be in contact with the solution.

MI 611-190 – January 2021

Electronic

Bench

Calibration

Figure 20. Flow Chart for pH/ORP/ISE Sensor Calibration

Install

Sensor

Check Temp Calibrate

5. Calibration tCF

Single Buffer/

Standard

Solution

Two Buffer/

Standard

Solution

AND/OR

Grab

One and Two Point Calibration

Figure 21. Flow Chart for Single Point Calibration

Sensor Remove Clean

Immerse in

Buffer/

Standard

CAL LO

Sensor

Figure 22. Flow Chart for Two Point Calibration

Remove Clean

Low

Buffer/

Standard

Rinse

High

Buffer/

Standard

CAL LO

The procedure for performing one and two point calibration is as follows:

CAL HIGH

5. Calibration MI 611-190 – January 2021

1. Unlock analyzer (see ).

2. Remove the sensor from the process stream. Clean the immersion end and rinse with distilled water.

3. Select buffers or standard solutions near or bracketing the process measurement value.

The solutions should be at the same temperature and, for best results, near the process temperature.

4. Immerse the cleaned sensor in the solution with lower known pH, ORP, or ion concentration. Wait until the sensor has reached chemical and thermal equilibrium.

5. Press/hold SHIFT and press CAL LO. Remove fingers from both keys.

6. Press NEXT and Δ repeatedly until the display reads the correct value at the temperature of measurement. Press ENTER.

NOTE

For single point standardization, stop here. The slope (gain) from the previous bench or solution calibration will be used.

7. Thoroughly rinse the sensor in distilled water.

8. Immerse the sensor in the second solution with higher known pH, ORP, or ion concentration. Allow the sensor to come to chemical and thermal equilibrium.

9. Press SHIFT and while holding, press CAL HI. Remove fingers from both keys.

10. Use NEXT and Δ until display reads the correct value. Press ENTER.

11. Lock analyzer (see “Locking Analyzer Using Security Code” on page 38).

Grab Sample Standardization

Figure 23. Flow Chart for Grab Sample Calibration

Sample Note Analyze Correct

CAL LO

MI 611-190 – January 2021 5. Calibration

The procedure for grab sample calibration is:

1. Unlock analyzer (see “Unlocking Analyzer Using Security Code” on page 38).

2. Note the present pH, ORP, or ion concentration reading while extracting a sample from the process stream.

3. Determine the pH (ORP or ion content) of the sample using laboratory techniques suitable for the precision required. The laboratory measurement should include precise standardization and temperature compensation of the laboratory sensor, and should protect the sample from atmosphere and temperature change.

4. Determine the difference between the laboratory value and process reading taken when the sample was removed.

5. Using the CAL LO sequence, adjust the present reading by the difference calculated.

EXAMPLE:

When the sample was taken, the analyzer read 8.25 pH. The grab sample was found by the laboratory to be 8.40 pH. When you returned to the analyzer, the display read 8.30 pH. This value should be increased by +.15 pH units (8.40 – 8.25 =.15) to 8.45 using the CAL LO key and Δ .

6. Press SHIFT and while holding, press CAL LO. Remove fingers from both keys.

7. Use NEXT and Δ until the display reads the corrected measurement value. Press

ENTER.

8. Repeat Steps 2 through 7 to verify the standardization.

Temperature Cell Factor

Except for ORP measurements, which do not use temperature compensation, an accurate temperature signal is required, especially when measuring over a large temperature gradient. The temperature cell factors (tCF1 and tCF2) are used to offset a deviation from ideal caused by high cable resistance. The procedures found in the following sections are recommended for installations that require a cable length of 50 feet or greater. The 873 analyzer uses a 100-ohm

RTD circuit for automatic temperature compensation. Use this procedure before executing buffer or grab sample calibrations.

5. Calibration MI 611-190 – January 2021

Determining tCF

The procedure for determining the temperature cell factor is:

1. Place the sensor and an accurate Centigrade thermometer (with 1.00 ºC resolution) into a container of liquid. Allow the system to reach thermal equilibrium.

2. Press TEMP. Put the analyzer into Automatic Temperature Compensation (no decimal after the C). If there is a decimal after the C, remove it. Press Δ once after pressing TEMP; then press ENTER.

3. Read the temperature displayed on the 873 to the hundredths place.

When TEMP is pressed, the current temperature value with tenths place display will alternate with the C legend. The value read by the 873 may now be viewed to the hundredths place. Press TEMP followed by NEXT five times. Only three numbers may be viewed on the display, and the first digit will not be visible (e.g., 25.20 will be displayed as 5.20).

4. Determine the difference in values between the two temperature devices; e.g., the thermometer reads 24.70 ºC, and the 873 reads (2)5.20 ºC; the 873 is reading higher by 0.50 ºC.

5. Subtract this value from 25.00 (e.g., 25.00 –.50 = 24.50). This is your new tCF value.

NOTE

If the 873 value is less than the thermometer reading, add the difference to 25.00.

Entering a tCF Value

To enter a tCF value, execute the following procedure:

1. Unlock analyzer (see “Unlocking Analyzer Using Security Code” on page 38).

2. Press SHIFT + SETUP. Release both keys.

3. Press NEXT several times until the code bL (Basic Setup Lock) is displayed.

4. Press ENTER. Then press NEXT and Δ repeatedly until personal security code is displayed (0800 from factory).

5. Press ENTER.

6. When the display returns to bL , press NEXT several times until the parameter identifier tCF1 or tCF2 is displayed.

7. Press ENTER and then press NEXT and Δ one or more times until desired value is displayed.

8. Press ENTER.

9. Recheck any differences that exist between a thermometer reading and the temperature displayed on the 873, using the technique described earlier in this chapter.

10. Lock analyzer.

MI 611-190 – January 2021 5. Calibration

6. Diagnostics

Troubleshooting

Using the 873 Analyzer to Troubleshoot a Sensor Problem

The best way to check the health of a sensor is to hook it up to an analyzer and to calibrate it in

pH buffers or standard solutions (refer to “One and Two Point Calibration” on page 76). First,

make sure that buffers or standard solutions are fresh and uncontaminated. Then, let the sensor reach thermal and chemical equilibrium with the solution. If the sensor calibrates accurately, you

can be sure it is fully functional. If it does not, refer to the section on “Additional

Troubleshooting” on page 83.

873 Error Codes/Actions

When the sensor is used in conjunction with an 873 analyzer, the analyzer displays an error code

if certain fault conditions exist. (Refer to Table 7, “Error/Alarm Messages,” on page 85 for an

explanation of each.) Use of the error codes in diagnosing sensor problems is described below.

Er 1 (Instrument Fault):

♦ Disconnect the sensor and power down the analyzer. Try the sensor on another unit.

Er 2 (Temperature Error):

♦ The temperature sensor used on the 873DPX is a 100 ohm RTD. At temperatures around 25°C (77°F), it should read 110 ohms. Check to see what values (typically 0 to 100) are assigned to tL and LtL. Then press TEMP (Auto mode). If the display reads incorrectly, determine whether the analyzer or sensor is not functioning. To check the analyzer, place a 110-ohm resistor across Terminals 1 and 2 of terminal block TB2 and verify that the analyzer reads 25 ºC. If it does not, a fault exists in the analyzer. If it does, proceed to the next step.

♦

Next, measure the resistance between wires 1 and 2 (black and white) of the sensor. At normal room temperatures, the resistance should be approximately 110 ohms. If the resistance between Leads 1 and 2 of the sensor deviates greatly from 110 ohms, the sensor is not functioning properly and should be replaced. For the short term, if the process measurement does not change temperature and is close to pH 7, or has very wide accuracy specifications, manual temperature compensation may be selected.

MI 611-190 – January 2021 6. Diagnostics

Er 4 (Calibration Error):

♦ During 2-point calibration with fresh non-contaminated solutions, a sensor may cause an Er 4 error message to appear if the sensor does not generate a large enough voltage difference between the two measurements. If, however, the sensor is sufficiently conditioned and relatively stable in each solution, additional conditioning time may improve the response. Soak your electrode in dilute KCl solution without silver chloride. To hydrate the glass bulb, soak sensor in pH 4 buffer solution for approximately 15 minutes.

♦ Note that a new sensor installation may also experience this problem. Recovery may be hastened by immersing the sensor in a warmed KCl solution and then cooling it to room temperature while immersed in this solution. If the sensor reads the same value in every solution after hydration and proper conditioning, replace the sensor.

♦ The 873DPX analyzer will accept a 2-buffer calibration (Er 4 not activated) as long as

the slope (mV/pH or mV/ppm decade) of the calibration curve (see Figure 24)

exceeds ~50 mV. Slope value may be accessed by pressing SHIFT + SLOPE. Slope is always displayed at a temperature of 25.0 ºC, regardless of the temperature at which calibration occurred. If the slope falls below 50.3, the calibration will still be accepted into the unit, but Er 4 will flash and alternately display the sample value.

Sensor servicing is recommended on all sensors with slopes below 53.3 mV/pH

(90% efficiency). See Item 2, “Low Slope”, in the following section.

Verify that the temperature is reading correctly and the analyzer is in the automatic

temperature mode. See Chapter 3

♦ Use the correct buffer values at the temperature of measurement.

Table 6. Temperature vs. Resistance Table for Pt 100 RTD

Temperature

(°C)

–5

Resistance

(ohms)

98.04

100.00

101.95

103.90

105.85

107.79

109.73

111.67

113.61

Temperature

(°C)

100

110

Resistance

(ohms)

115.54

119.40

123.24

127.07

130.89

134.70

138.50

142.29

6. Diagnostics MI 611-190 – January 2021

Additional Troubleshooting

1. SENSOR DOES NOT APPEAR TO BE FUNCTIONING.

For sensors with a preamplifier, leave all sensor leads connected to the analyzer. Leave analyzer power on. Connect a voltmeter first to Leads 4 and 6 of TB2, and then to

Leads 4 and 7. The voltmeter should read ±6.2 V. If it does not, disconnect the sensor and repeat the procedure at the analyzer. If ±6.2 V can be measured at the analyzer terminals, a problem exists in the sensor. If ±6.2 V is not present at the analyzer terminals, an analyzer problem exists. If the sensor and analyzer both pass this test, continue to Item 2.

2. LOW SLOPE.

Leave all sensor leads connected to the powered analyzer. Clean the “business end” of the sensor and place into a beaker of pH 7 buffer. Use the mV key to display the measured absolute voltage generated by the sensing and reference electrodes. The value should be 0 V ±20 mV. When the sensor is cleaned and placed into a second buffer (25 ºC), the reading should change approximately 59 mV per pH unit. In a

10.0 pH buffer, the mV reading should be less than the 7 pH buffer reading by approximately 174 mV (177.3 theoretically). In a 4.00 pH buffer, the mV value should be greater than the mV value in the 7 pH buffer by 174 mV. If the sensor passes this test and the problem with the measurement persists, an analyzer problem may exist. Verify that the sensor temperature is in automatic mode and that it is reading correctly.

NOTE

HINT: It is a good idea to keep records of your calibrations. Recording the mV values and Slope can help you establish maintenance and replacement information on your sensors.

3. ERRATIC READING.

On 871PH pH/ORP/ISE only: Measure the resistance between wire #4 (clear) and the knurled screw on the immersion end of the sensor. The resistance should be 0

(shorted) or very small. If not, you have a grounding problem with your sensor.

For an 871A, make sure the grounding threads are in contact with the solution. Teflon tape around these threads may prevent a ground connection from being made.

Troubleshooting a ground loop or grounding problem may also be done in a beaker of buffer. Immerse a sensor in buffer other than pH 7 and note the pH. Attach a wire to a piece of metal (a paper clip will do) and to an earth ground (metal pipe or outlet ground). Next, place the metal piece into the beaker and observe the pH reading of the analyzer. It should not change. A change in pH during this procedure indicates that a problem exists.

MI 611-190 – January 2021 6. Diagnostics

4. SLOW RESPONSE.

If the sensor is very slow in responding, a blockage may have occurred on the reference junction. (To dissolve dried salts, condition the sensor longer. Otherwise, replace the reference solution, especially if it is discolored.) Trapped air bubbles can also cause problems by increasing resistance in this circuit. A firm shakedown and soaking can often help. Slow response can also indicate a coated or dehydrated pH glass. Although cleaning or soaking the sensor in pH 4 buffer or dilute acid may help, replacement of the pH electrode may be required. Also refer to the Er 4 troubleshooting procedures described earlier in this section.

600

500

400

300

200

100 mV 0

-100

-200

-300

-400

-500

-600

Cal Lo

ISOPOTENTIAL POINT

TEMPERATURE (C) SLOPE (MV)

0 54.2

25 59.2

50 64.1

75 68.1

100 74.0

Cal Hi

0 C

25 C

50 C

70 C

100 C

14 0 2 4 6 pH

8 10

Figure 24. Relationship between pH and mV at Different Temperatures for a Standard Glass pH Sensor and Ag/AgCl Reference Electrode

6. Diagnostics MI 611-190 – January 2021

Error Codes

When the analyzer is operating normally, the measurement value is displayed constantly. If error or alarm conditions exist, the display alternates between the measurement value and the error/alarm message at a one second rate. The alternate (error/alarm) messages are shown in the following tables.

Table 7. Error/Alarm Messages

Alternate

Display

Er1

Er2

Condition

Instrument fault, RAM/ROM, software watchdog timer

User-defined temperature range error or temperature measurement error

Priority

(highest)

Er3

Er4

User-defined measurement range error 7

Measurement calibration incorrect 2

Action Required to Clear Error Message

Re-enter security code.

Power cycle unit.

Change user-defined temperature limits, UtL or LtL.

Replace sensor.

Place temperature in manual mode.

Change user-defined measurement limits, UL or LL.

Replace sensor.

Ground loop.

Recalibrate sensors on both channels.

Al 1

Al 2

A1A2

....

Err

Alarm 1 relay activated

Alarm 2 relay activated

Both alarm relays activated

Measurement over or under range of analog output limits

Incorrect code or parameter attempted

Check analog output limits.

Check code and re-enter.

MI 611-190 – January 2021 6. Diagnostics

7. Alarm Contact Maintenance

The alarm relay contacts are selected to switch loads equal to or greater than 20 watts. The minimum contact current is 1 ampere. The silver alloy contacts rely on the very slight arc generated during switching to eliminate oxide layers that form on the contacts. When the contacts are used at low (signal) levels, contact function may become unreliable over time due to the formation of an oxide layer on the contacts.

When contacts must be used at low levels, attention must be paid to contact condition. The maximum contact resistance for new relays is 100 milliohms. Values above this level or unstable values indicate deterioration of the contact surface as noted above and may result in unreliable alarm function.

The contact surfaces can be restored as follows:

1. Disconnect the alarm wiring from the analyzer.

2. Connect a load of 20 W or more as shown in Figure 25 so that both NO and NC

contacts are exercised.

3. Use the analyzer to switch the alarm relay several times.

4. Disconnect the load installed in Step 2 and reconnect the wiring removed in Step 1.

5. Check to ensure that the alarms are functioning properly.

Figure 25. Alarm Contact Reconditioning Circuit

20 W LOAD

120 V ac SUPPLY

MI 611-190 – January 2021

ISSUE DATES