TPS miniCHEM-pH User manual

Congratulations !
Your new miniCHEM-pH monitor is the latest in simple, reliable process
monitoring instrumentation. With correct operation and maintenance, your
miniCHEM-pH will give you many years of reliable service.
The miniCHEM-pH is a breeze to operate. This manual has been designed to
help you get started, and also contains some handy application tips. If at any
stage you require assistance, please contact either your local TPS representative
or the TPS factory in Brisbane.
The manual is divided into the following sections:
1. Table of Contents
Each major section of the handbook is clearly listed. Sub-sections have also
been included to enable you to find the information you need at a glance.
2. Introduction
The introduction has a diagram and explanation of the display and controls of
the miniCHEM-pH. It also contains a full listing of all of the items that you
should have received with the unit. Please take the time to read this section, as
it explains some of items that are mentioned in subsequent sections.
3. Main Section
The main section of the handbook provides complete details of the
miniCHEM-pH, including operating modes, calibration, troubleshooting,
specifications, and warranty terms.
4. Appendices
Appendices containing background information and application notes are
provided at the back of this manual.
miniCHEM-pH
Process Monitor
Version : 2.11
Date : 10/09/2002
Author : MS

Page 2
TPS Pty Ltd
ABN 30 009 773 371
4 Jamberoo Street
Springwood, Brisbane,
Australia, 4127
Phone : [phone]
International : 61 7 32 900 400
Fax : [phone]
International : 61 7 3808 4871
Email : [email protected]
Web : www.tps.com.au

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Contents
1. Introduction .............................................................................................4
1.1 miniCHEM-pH Illustration...............................................................................4
1.2 Unpacking Information....................................................................................6
1.3 Specifications...................................................................................................7
2. Operating Modes .....................................................................................8
3. Installation and Set-up............................................................................9
3.1 Connection and Configuration Diagram...........................................................9
3.2 Mounting the Enclosure.................................................................................10
3.3 Mounting the Sensors.....................................................................................10
3.4 Terminal Connections....................................................................................11
3.5 Setting the Control Limit ...............................................................................12
3.6 Selecting Current or Voltage Output ..............................................................14
3.7 Calibrating the 4 to 20mA Output..................................................................15
3.8 CMRR Control...............................................................................................15
3.9 Factory Config. Jumpers.................................................................................15
4. Calibration..............................................................................................16
4.1 Calibration Procedure.....................................................................................16
4.2 Calibration Notes ...........................................................................................17
5. Process Monitoring...............................................................................18
6. Automatic Dosing..................................................................................18
7. Manual Dosing.......................................................................................18
8. Fuse Replacement.................................................................................18
9. Troubleshooting....................................................................................19
9.1 Instrument Function Troubleshooting.............................................................19
9.2 pH Troubleshooting........................................................................................20
10. Warranty.............................................................................................21
11. Appendices ........................................................................................23
11.1 Checking the reference junction of a pH electrode......................................23
11.2 Determining if an instrument or electrode is faulty.....................................23
11.3 Terminal connections when 12V DC option is fitted ..................................24
11.4 Relay Output Wiring Examples for mains powered units............................25
11.5 Relay Output Wiring Examples for 12V DC powered units ........................26
11.6 Drilling Template ......................................................................................27

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1. Introduction
1.1 miniCHEM-pH Illustration

Page 5
¬Alarm LED
The Alarm LED provides visual indication of when the control limit has been
exceeded. The control limit can be set for a “too high” or a “too low” alarm.
See section 3.5.
-Limit Control
Adjust this control to the pH value at which the Alarm LED and (optional)
relay output are activated. See section 3.5.
®Zero Calibrate Control
Adjust this control to calibrate the miniCHEM-pH in a pH6.88 or pH7.00
buffer. See section 4.1.
¯Span Calibrate Control
Adjust this control to calibrate the miniCHEM-pH in a buffer several pH
away from pH7 (e.g. pH4.00 or pH9.23). See section 4.1.
°Function Switch
The Function Switch is used to select the mode of operation. See section 2.
±Display Window
The miniCHEM-pH has a large, easy to read LCD display. The units of
measurement are clearly shown in the window beneath the display.
ÆTerminal Cover
The terminal cover provides easy access to all of the connections, (optional)
relay output fuse, configuration jumpers and user-adjustable trimmers. The
cover is water resistant to IP65.

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1.2 Unpacking Information
Before using your new miniCHEM-pH, please check that the following
accessories have been included: Part No
1. miniCHEM-pH Process Monitor........................... 111140
2. pH6.88 Buffer, 200mL ..........................................121306
3. pH4.00 Buffer, 200mL ..........................................121381
4. miniCHEM-pH Handbook....................................130050
Options that may have been ordered with your miniCHEM-pH:
Dip mounted pH and ATC Sensors, and submersible assembly…
1. Submersible, Non-flow pH Sensor, 5m................... 111228
2. Intermediate Junction pH Sensor, 5m......................111227
3. Industrial 12K ATC Sensor, 5m.............................111275
4. Submersible protective housing for pH & ATC ......111303
Screw-in pH and ATC Sensors, and adaptor for 40mm PVC pipe…
1. Screw-in, Non-flow pH Sensor, 5m........................ 111244
2. Screw-in Industrial 12K ATC Sensor, 5m .............. 111265
3. ¼” BSP thread adaptor for 40mm PVC pipe...........111305
Instrument options…
1. Relay control output...............................................130342
2. 4-20mA loop-powered, remote LCD....................... 130080

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1.3 Specifications
Range.............................................................................................0 to 14.00 pH
Resolution .............................................................................................. 0.01 pH
Accuracy.............................................................................................. ±0.01 pH
Linearity............................................................................................... ±0.01 pH
Repeatability......................................................................................... ±0.01 pH
Ambient Drift ............................................................. <0.01 pH per 10oC change
Long term drift ............................................................................ <0.1% per year
Input Impedance ................................................................................>3 x 1012 Ω
Asymmetry Range................................................................................. ±1.00 pH
Slope Range.......................................................................................80 to 110%
Temperature Compensation.............Automatic, 0 to 100.0 oC (with ATC Sensor),
or fixed at 25 oC with 12K resistor.
Common Mode Rejection..........................................................................120 dB
Enclosure........................................................ Polycarbonate, waterproof to IP65
Display...........................................12.7 mm LCD (optional remote 4-20mA loop
powered display available)
Analogue Outputs............................4 to 20mA (500 Ohms max. loop resistance )
0 to 1 V DC (min. load 1000 Ω)
0 to 10 V DC optional (min. load 1000 Ω)
Control Output (optional).....................................Clean contact changeover relay,
rated to 2A at 240V AC
Isolation............................................................Galvanic isolation of sensor input
Power.....................................................240V AC, 50/60Hz (120V AC optional)
Dimensions............................................................................172 x 160 x 71 mm
Mass ...................................................................Instrument only :Approx 800g
Full Kit :Approx 1.5kg
Operating Environment:.......................................Temperature :0 to 45 oC
Humidity :0 to 95 % R.H.

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2. Operating Modes
The function switch is used to select the required mode. The four operating modes
available are…
1. SET LIMIT :Switch to SET LIMIT when setting the pH value at which the
Alarm LED and (optional) relay output are activated. The
relay output is not operational in this mode. See section 3.5.
2. STANDBY :Switch to STANDBY to inhibit the Alarm LED and
(optional) output relay action. Select this mode for calibration,
or when automatic dosing is not required.
3. AUTO :Switch to AUTO to enable the Alarm LED and (optional)
relay output. These will be activated when the pH is outside
the limit value. See section 3.5.
4. MANUAL :Switch to MANUAL to manually dose acid or base when the
optional relay output is fitted. The relay output will be
activated for as long as the miniCHEM-pH is in this mode,
regardless of the pH reading. See section 7.

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3. Installation and Set-up
3.1 Connection and Configuration Diagram
The diagram below is provided as a reference for the terminal connections,
configuration jumpers and user-adjustable trimmers that are discussed throughout
this section.

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3.2 Mounting the Enclosure
The miniCHEM-pH can be wall-mounted with 3 screws. Two mounting points are
located underneath the terminal cover, and are positioned so that they do not affect
the waterproofing of the enclosure. The third mounting point is centrally located
near the top of the rear of the enclosure, and has been designed to hook over a
screw-head. The dimensions for the mounting screw centres are provided on the
rear of the enclosure. The last page of this manual may be photocopied or removed
for use as a drilling template.
3.3 Mounting the Sensors
Mounting the sensors is a very important aspect of the installation, and is often
done incorrectly. In automatic control situations, the sensors should always be
mounted as close as possible to the injection point. This will cause the sensors to
detect the added chemicals immediately, and shut the addition off until mixing has
taken place. For in-line mounting, it is important that chemicals are injected
upstream. Additionally, the line must be run through a mixing chamber, such as a
large drum, to ensure that the injected chemical has mixed in properly by the time
the solution flows past the sensors. There must always be adequate flow of fresh
sample past the sensor, for accurate monitoring. The diagrams below show typical
mounting arrangements for “dip” mounting and in-line mounting.
Dip Mounting In-line Mounting
1. Injection point close to sensor. 1. Injection point upstream from
2. Submersible housing to protect and close to sensor.
sensors and waterproof rear of 2. Mixing container after injection
cable (part no 111303). and before sensor.
3. Continuous stirring. 3. pH sensor mounted as close to
vertical as practical.

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3.4 Terminal Connections
Note: The power connections detailed below are for normal mains power. Refer
to section 11.3 for power wiring details when the 12V DC power option is fitted.
Terminal No. Connection Colour
112K ATC Sensor * Black
212K ATC Sensor Common * Clear
3Solution Guard Green of ATC Sensor
OR:
Solution guard rod, if no
ATC Sensor is installed.
4pH Shield (if fitted) Green
5pH Reference Black
6pH Signal Clear or White
7+ve of current or voltage output Customer-defined
8-ve of current or voltage output Customer-defined
9No Connection
10 Normally Closed contact of
(optional) relay output Customer-defined
11 Common contact of (optional) relay
output Customer-defined
12 Normally Open contact of
(optional) relay output Customer-defined
13 240V AC Active input Brown (standard colour)
14 Duplicate 240V AC Active contact.
See section 11.3.Brown (standard colour)
15 240V AC Earth input Green (standard colour)
16 Duplicate 240V AC Earth contact.
See section 11.3.Green (standard colour)
17 240V AC Neutral input Blue (standard colour)
18 Duplicate 240V AC Neutral
contact. See section 11.3.Blue (standard colour)
∗∗ If an ATC sensor is not fitted, then a 12K resistor may be connected between
terminals 1 and 2 to simulate 25 oC. If this is done, then a stainless steel
solution guard rod must be connected to terminal 3.

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3.5 Setting the Control Limit
The control limit can be set over the full scale of the miniCHEM-pH, as a “too
high” or a “too low” trip point. The hysteresis around this set point can be also be
adjusted, if necessary. See section 3.5.3 for an explanation of hysteresis.
3.5.1 Setting the limit value
1. Switch the miniCHEM-pH to SET LIMIT.
The control limit value is now displayed. Note that the Alarm LED and
(optional) output relay are now disabled. The 4-20mA or 0-1V outputs are still
active, and proportional to displayed value.
2. Adjust the LIMIT control until the display reads the desired trip point value.
3.5.2 Setting the alarm/control direction
The control limit can be set as a “too high” or “too low” trip point using the Lo/Hi
Control jumpers in the terminal area. The miniCHEM-pH must be switched OFF
before changing jumper settings.
The jumper settings for a “too low” trip point are…
Low High
The jumper settings for a “too high” trip point are…
Low High

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3.5.3 Adjusting the Hysteresis
The hysteresis is the pH range over which the alarm/control output remains
switched on, once the trip point has been exceeded.
For example, if the limit is set to pH7.00, as a “too low” trip point, with a
hysteresis of ±0.10pH, the alarm/control output is switched ON when the reading
goes to pH6.90 (i.e. 7.00 -0.10). The output is not switched OFF until the reading
goes back up to pH7.10 (i.e. 7.00 + 0.10).
The hysteresis stops the relay “chattering” around the set point, by providing a
buffer between the points at which the output is switched ON and OFF. This
feature can significantly increase the life of pumps and solenoid valves.
The factory-set hysteresis is approximately ±0.10 pH, as in the example above.
The hysteresis can be increased to as high as ±0.40 pH with the HYSTERESIS
trimmer in the terminal area. Turning the HYSTERESIS clockwise increases the
hysteresis and turning it anti-clockwise decreases the hysteresis.
TPS DOES NOT recommend that this setting be altered, unless it is absolutely
necessary.
The HYSTERESIS trimmer should only be adjusted a little at time. The process
being controlled should then be closely monitored over a time to ensure that the
desired control is being achieved.

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3.6 Selecting Current or Voltage Output
The Current/Voltage Output jumpers in terminal section can be user-set for
either 4 to 20mA or 0 to 1V DC output. The miniCHEM-pH must be switched
OFF before changing jumper settings.
The jumper settings for 4 to 20 mA output are:
CVCVC
The jumper settings for 0 to 1V DC output are:
CVCVC
Note that the spare jumper has been fitted to a spare Current/Voltage Output
jumper pin. This is a safe place to keep it, in case the miniCHEM-pH needs to be
reset to current output in the future.
0 to 10V DC output is available as a factory fitted option. The jumper settings
are the same as detailed above, but the 0 to 1V DC output will no longer be
available.

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3.7 Calibrating the 4 to 20mA Output
The 4 to 20mA output of the miniCHEM-pH is factory calibrated. However, TPS
has provided calibration controls for the 4mA and 20mA points in case this
requires adjustment in the field. Only a limited amount of adjustment is available,
as the miniCHEM-pH is designed for 4 to 20mA output for the full scale of the
instrument.
Calibrating the 4 to 20mA output…
1. Connect a Digital Milliamp Meter between terminals 7 and 8.
2. Switch the miniCHEM-pH to SET LIMIT.
3. Adjust the LIMIT control until the display reads 0.00.
4. Adjust the ZERO/4mA trimmer in the terminal area until the Digital Milliamp
Meter reads 4 mA.
5. Adjust the LIMIT control until the display reads 14.00.
6. Adjust the SPAN/20mA trimmer in the terminal area until the Digital
Milliamp Meter reads 20 mA.
In the event that the LIMIT control does not have sufficient adjustment to
reach 0.00 or 14.00, calculate the expected output level and use this for
calibration. Remember that the difference between 0 and 14 pH is to be made
16mA.
3.8 CMRR Control
The Common Mode Rejection Ratio (CMRR) is factory-set with the CMRR
trimmer.
DO NOT ATTEMPT TO ADJUST THE CMRR TRIMMER.
If this trimmer is accidentally re-set, the unit would best be returned to the factory
for re-calibration.
3.9 Factory Config. Jumpers
The Factory Config. jumpers are factory set, and must not be altered. In case
any of these jumpers are changed or removed, re-fit them as shown below. The
miniCHEM-pH must be switched OFF before changing jumper settings.
Factory
Config.

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4. Calibration
4.1 Calibration Procedure
1. Switch the miniCHEM-pH on.
2. Ensure that the pH and ATC sensors are correctly connected (see section 3.4).
If no ATC sensor is fitted, then a 12K resistor should be connected between
terminals 1 and 2. A stainless steel guard rod should then be substituted for the
ATC sensor during the calibration procedure detailed below.
3. Set the function switch to STANDBY, to ensure that the (optional) relay
output is not activated when moving the pH sensor from buffer to buffer.
4. Remove the wetting cap from the pH sensor.
5. Rinse the pH and ATC sensors in distilled water and blot them dry.
Asymmetry (Zero) Calibration
6. Place both sensors into a small sample of pH6.88 or pH7.00 buffer, so that the
bulb and reference junction are both covered (see diagram below). DO NOT
place the electrodes directly into the buffer bottle. Discard the used buffer after
use.
1. When the reading has stabilised, adjust the ZERO control until the display
shows the value of the buffer. The pH6.88 buffer supplied by TPS lists the pH
value of the buffer at various temperatures.
2. Rinse the pH and ATC sensors in distilled water and blot them dry.

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Span Calibration
3. Place both sensors into a small sample of pH buffer, that is several pH away
from pH7 (e.g. pH4.00 or pH9.23). Ensure that the bulb and reference junction
are both covered (see diagram in step 6, above). DO NOT place the electrodes
directly into the buffer bottle. Discard the used buffer after use.
NOTE: pH buffers above pH9 are highly unstable. Avoid using these
buffers if possible. Discard immediately after use.
pH4.00 buffer is recommended for its stability. Most users report
readings up to pH12 to be more accurate when using this buffer
than when using pH9.23 or pH10.00 buffer for span calibration.
4. When the reading has stabilised, adjust the SPAN control until the display
shows the value of the buffer. The pH4.00 buffer supplied by TPS lists the pH
value of the buffer at various temperatures.
5. Rinse the pH and ATC sensors in distilled water and blot them dry.
6. The miniCHEM-pH is now calibrated and ready for pH measurements.
4.2 Calibration Notes
1. An Asymmetry (Zero) calibration should be performed at least weekly. In
applications where the electrode junction can become blocked, such as dairy
products, mining slurries etc, an asymmetry calibration may have to be done
daily.
2. A full 2-point Asymmetry and Span calibration should be performed at least
monthly. Of course, more frequent calibration will result in greater confidence
in results.

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5. Process Monitoring
Once the miniCHEM-pH has been installed, connected and calibrated, it can be
used for continuous monitoring. To monitor the process, WITHOUT any control or
alarm functions switch the function switch to STANDBY.
6. Automatic Dosing
For Automatic Alarming or Control, switch the function switch to AUTO to enable
the Alarm LED and the (optional) relay output. These will be switched ON while
the pH exceeds the limit value, and will switch OFF once the pH is back within the
limit.
7. Manual Dosing
From time to time, a dose of chemical may be required even when the pH is within
the limit value. To do this, simply switch the function switch to MANUAL, if the
(optional) relay output is fitted.
NOTE: The output will be ON continuously while the function switch is set to
MANUAL. It will not be switched OFF again until the switch is set back
to one of the other modes.
8. Fuse Replacement
If the current drain from any device connected to the output relay exceeds 1Amp,
the output protection fuse will blow.
To replace the fuse…
1. SWITCH THE miniCHEM-pH OFF.
2. Pull out the black fuse carrier.
3. Replace the blown fuse
4. Push the fuse carrier with the new fuse back into place.
ALWAYS REPLACE THE FUSE WITH A 1 AMP, 240V
FUSE. USING A FUSE WITH HIGHER CURRENT RATING
MAY DAMAGE YOUR CONTROLLER, VOIDING THE
WARRANTY.
Before switching the miniCHEM-pH back to AUTO mode, ensure that the cause
of the blown fuse has been eliminated.
If the current drain of the device connected to the relay output is greater than 1
Amp, an external contactor should be used. Please consult an electrical contractor
or TPS for details.

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9. Troubleshooting
9.1 Instrument Function Troubleshooting
Symptom Possible Causes Remedy
No display 1. Mains power input not
switched on.
2. Mains power input
incorrectly connected.
3. Instrument is faulty.
Switch power ON.
Check connections (see section
3.4).
Return to TPS for repair.
Alarm LED or
(optional) relay
output do not
operate when limit
is exceeded.
1. Limit not set correctly for
“too high” or “too low”
alarm/control.
2. Optional relay output not
fitted.
3. Hysteresis too large.
4. Fuse has blown.
5. Instrument is faulty.
Set the Lo/Hi Output jumpers
correctly (see section 3.5.2).
Return unit to factory to have
relay output fitted (part no
130342).
Check and adjust the
HYSTERESIS trimmer (see
section 3.5.3). If in doubt, set
this to minimum level.
Check and replace fuse if
necessary (see section 8).
Return to TPS for repair.
Incorrect analogue
output signal. 1. Current/Voltage Output
jumpers incorrectly set for
required output.
2. 4-20mA loop resistance too
high.
3. Load on 0-1V DC output is
too low.
4. 4-20mA output is not
calibrated.
5. Instrument is faulty.
Check that the Current/Voltage
Output jumpers are correctly
set for 4-20mA or 0-1V, as per
requirements. Adjust if
necessary (see section 3.6).
Ensure loop resistance does not
exceed 500 Ohms.
Ensure load is 1000 Ohms
minimum.
Calibrate 4-20mA output (see
section 3.7).
Return to TPS for repair.

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9.2 pH Troubleshooting
Symptom Possible Causes Remedy
Asymmetry (Zero)
calibration fails
(insufficient range
with ZERO
control).
1. Reference junction blocked.
2. Reference electrolyte
contaminated.
Clean reference junction, as per
instructions supplied with the
electrode.
Flush with distilled water and
replace electrolyte.
Span calibration
fails (insufficient
range with SPAN
control).
1. ATC probe not connected.
2. Glass bulb not clean.
3. Electrode is aged.
4. Buffers are inaccurate.
Connect ATC probe to
terminals 1 & 2 (see section
3.4).
Clean glass bulb as per
instructions supplied with the
electrode.
Attempt rejuvenation, as per
instructions supplied with the
electrode. If not successful,
replace electrode.
Replace buffers.
Unstable readings. 1. Solution guard not fitted.
2. Reference junction blocked.
3. Glass bulb not clean.
4. Bubble in glass bulb.
5. Reference junction not
immersed.
6. KCl crystals around
reference junction, inside
the electrolyte chamber.
Connect the green wire from
the ATC (or solution guard rod
if no ATC sensor is fitted), to
terminal 3 (see section 3.4).
Clean reference junction, as per
instructions supplied with the
electrode.
Clean glass bulb as per
instructions supplied with the
electrode.
Flick the electrode to remove
bubble.
Ensure that the bulb AND the
reference junction are fully
immersed.
Rinse electrolyte chamber with
warm distilled water until
dissolved. Replace electrolyte.
Inaccurate readings,
even when
calibration is
successful.
Reference junction blocked. Clean reference junction, as per
instructions supplied with the
electrode.
Displays around 7
pH in all solutions Electrical short inside electrode or in cable. Test system with a new electrode and replace if
necessary.
Displays 4-5 pH for
all solutions. Glass bulb or internal stem cracked. Replace electrode.