TPS pH Cube User manual

Congratulations !
You have purchased the latest in benchtop pH-ORP-Temperature
instrumentation. We trust that your new pH Cube will give you many years of
reliable service.
The pH Cube 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 pH Cube. It also contains a full listing of all of the items that you should
have received with your pH Cube. 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 pH Cube,
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.
TPS Pty Ltd
ABN 30 009 773 371
Unit 6 / 253 Leitchs Road
Brendale, QLD,
Australia, 4500
Phone : [phone]
International : 61 7 32 058 027
Fax : [phone]
International : 61 7 3808 4871
Email : [email protected]
Web : www.tps.com.au
Model pH Cube
pH-ORP-Temp.
Meter
Handbook Version : 1.3
Date : 12-Dec-11

Page 2
Contents
1. Introduction .................................................................................................. 3
1.1 pH Cube Front Panel and Controls................................................................... 3
1.2 pH Cube Side Panel and Connectors ................................................................ 4
1.3 Unpacking Information..................................................................................... 5
1.4 Specifications.................................................................................................... 5
2. Operating Modes..........................................................................................6
3. pH Calibration............................................................................................... 7
3.1 Calibration Procedure....................................................................................... 7
3.2 Calibration Notes.............................................................................................. 8
4. ORP/mV Calibration.....................................................................................8
5. Temperature Calibration .............................................................................9
5.1 Calibration Procedure....................................................................................... 9
5.2 Calibration Notes.............................................................................................. 9
5.3 Manual Temperature Setting ............................................................................ 9
6. Troubleshooting.........................................................................................10
6.1 pH and ORP/mV Troubleshooting ................................................................. 10
6.2 Temperature Troubleshooting......................................................................... 11
7. Appendices.................................................................................................12
7.1 pH Buffer Values Vs Temperature ................................................................. 12
7.2 pH Sensor Fundamentals................................................................................ 13
8. Warranty......................................................................................................16

Page 3
1. Introduction
1.1 pH Cube Front Panel and Controls
Display
12.7mm LED display with mode enunciator.
Function Switch
Switches between pH, ORP/mV and Temperature modes. See section 2.
Calibrate Control
Used for pH asymmetry calibration in pH7.00 or pH6.86 buffer. See section
3.
Slope Control
Used for pH slope calibration in a buffer that is at least 2 to 3 pH away from
pH7.00, eg. pH4.01, pH9.18 or pH10.01. See section 3.
Manual Temp Control
Used to manually set the temperature of the solution for pH temperature
compensation. Only active when temperature sensor is unplugged. See
section 5.3.

Page 4
1.2 pH Cube Side Panel and Connectors
pH / mV Connector
Used to connect pH, ORP (Redox) and Specific Ion sensors.
Ref Connector
Used to connect Reference sensor when a mono pH, ORP (Redox) or
Specific Ion sensor is connected to the pH / mV Connector.
Temp Connector
Used to connect Temperature sensor. This sensor provides temperature
readout as well as Automatic Temperature Compensation for pH readings.
Temp Cal Control
Used for temperature calibration. See section 5.
12V DC Power Connector
Used to connect 12V AC/DC Adaptor. The pH Cube can run off any 12V
DC source with at least 200mA output. The 12V DC connector has a
positive tip.

Page 5
1.3 Unpacking Information
Before using your new pH Cube, please check that the following accessories
have been included: Part No
1. pH Cube pH-ORP-Temperature Instrument 121122
2. Combination pH Sensor 121207
3. Temperature/ATC Sensor 121245
4. pH7.00 Buffer, 200mL 121387
5. pH4.01 Buffer, 200mL 121381
6. Rod and Clamp for 2 x 12mm and 1 x 6mm 121346
diameter sensor.
7. AC/DC Power Adaptor 130044
8. pH Cube Handbook 130050
1.4 Specifications
Ranges
Resolution
Accuracy
pH
0 to 14.00 pH
0.01 pH
±0.01 pH
ORP/mV
0 to ±1999 mV
1 mV
±1 mV
Temperature
-10.0 to 120.0 OC
0.1 OC
±0.2 OC
Input Impedance : >3 x 1012 
Asymmetry Range : Approx -1.00 to 1.00 pH
Slope Range : Approx 85.0 to 105.0%
Temperature Compensation : Automatic : 0 to 100.0 oC
Manual : 5 to 100 oC
Power : 12V DC by AC/DC power adaptor.
Dimensions : 120 x 120 x 120 mm
Mass : Instrument only : Approx 0.9 kg
Full Kit : Approx 2.1 kg
Environment Temperature : 0 to 45 oC
Humidity : 0 to 90 % R.H.

Page 6
2. Operating Modes
Switch the function switch to any one of the following three operating modes.
Note the mode enunciator –Pfor pH, Efor EMF (ORP/mV), and Cfor OC.
Function Switch
Position
Display example
pH
ORP/mV
Temp

Page 7
3. pH Calibration
3.1 Calibration Procedure
1. Switch the pH Cube to pH mode (see section 2).
2. Plug the pH sensor into the Sensor socket and the temperature sensor into
the Temp socket.
3. Ensure that temperature has already been calibrated or manually set (see
sections 5.1 and 5.3).
4. Remove the wetting cap from the pH sensor.
5. Rinse the pH and Temperature sensors in distilled water and blot them dry.
6. Place both sensors into a small sample of primary buffer that is at or near
pH7 (eg. pH7.00 or pH6.86). The bulb and reference junction should both be
covered, as per the diagram below.
DO NOT place the sensors directly into the buffer bottle.

Page 8
7. When the reading has stabilised, adjust the Calibrate control until
the display shows the value of the buffer at the current temperature. For TPS
buffers, this is shown on the bottle. Refer also to the table in section 7.1.
8. Rinse the pH and Temperature sensors in distilled water and blot them dry.
9. Place both sensors into a small sample of secondary buffer (eg. pH4.01,
pH9.18 or pH10.01) so that the bulb and reference junction are both
covered, as per the diagram in step 6 above.
DO NOT place the sensor directly into the buffer bottle.
pH9.18 and pH10.01 buffers are unstable once the bottles have been
opened. Discard immediately after use.
When the reading has stabilised, adjust the Slope control until the display
shows the value of the buffer at the current temperature. For TPS buffers,
this is shown on the bottle. Refer also to the table in section 7.1.
10. The pH Cube is now calibrated and is ready for use.
Discard the used samples of buffer.
3.2 Calibration Notes
1. A 1-point calibration using the Calibrate control in a pH7.00 or pH6.86
buffer should be performed at least weekly. In applications where the sensor
junction can become blocked (eg. wines, dairy products, mining slurries etc) a
1-point calibration may have to be done daily.
2. A full 2-point calibration should be performed at least monthly. Of course,
more frequent calibration will result in greater confidence in results.
4. ORP/mV Calibration
The mV section is factory calibrated. There is no user-calibration facility for this
mode.

Page 9
5. Temperature Calibration
The temperature readout must be calibrated or manually set before attempting pH
calibration.
5.1 Calibration Procedure
1. Switch the pH Cube to Temperature mode (see section 2).
2. Plug the temperature sensor (Part No 121245) into the Temp socket.
3. Place the sensor alongside a good quality mercury thermometer into a
beaker of room temperature water. Stir the sensor and the thermometer
gently to ensure an even temperature throughout the beaker.
4. When the reading has stabilised, adjust the Temp Cal. control until the
display shows the same temperature as the mercury thermometer.
5. The Temperature function of the pH Cube is now calibrated and is ready for
use.
5.2 Calibration Notes
1. Temperature does not need to be recalibrated unless the Temperature sensor
is replaced.
5.3 Manual Temperature Setting
Manual temperature setting is only available if the temperature sensor is not
plugged in.
1. Switch the pH Cube on and select Temperature mode (see section 2).
2. Measure the temperature of the sample solution.
3. Adjust the Manual Temp control until the display shows the measured
temperature of the sample solution.

Page 10
6. Troubleshooting
6.1 pH and ORP/mV Troubleshooting
Symptom
Possible Causes
Remedy
Meter displays
“-1. " as a
reading.
pH reading is over-ranged.
pH sensor not connected or
faulty. Replace sensor if
necessary.
Asymmetry
calibration with
Calibrate control
in pH7.00 or
pH6.86 buffer fails.
(Asymmetry is
greater than +/-1.00
pH.)
1. Reference junction blocked.
(See section 7.3)
2. Reference electrolyte
contaminated.
Clean reference by immersing
the probe in hot water (60C)
for a few minutes. Proteins can
be cleaned off using a pepsin
solution.
Replace electrolyte if using a
refillable sensor.
Slope calibration
with Slope control
in low or high
buffer fails. (Slope
is less than 85.0%.)
1. Glass bulb not clean.
2. Sensor is aged.
3. Connector is damp.
4. Buffers are inaccurate.
Clean glass bulb as per
instructions supplied with the
sensor.
Attempt rejuvenation, as per
instructions supplied with the
sensor. If not successful,
replace sensor.
Dry in a warm place.
Replace buffers.
Inaccurate readings,
even when
calibration is
successful.
Reference junction blocked.
(See section 7.3)
Clean reference junction by
immersing the probe in hot
water (60C) for a few minutes.
Displays around
pH7.00 for all
solutions.
Electrical short in connector.
1. Check connector. Replace if
necessary.
2. Replace sensor.
Displays 4-5 pH for
all solutions.
Glass bulb or internal stem
cracked.
Replace sensor.

Page 11
pH and ORP/mV Troubleshooting, continued…
Unstable readings.
1. Reference junction blocked.
2. Glass bulb not clean.
3. Bubble in glass bulb.
4. Faulty connection to meter.
5. Reference junction not
immersed.
6. KCl crystals around
reference junction, inside
the electrolyte chamber.
Clean reference junction as per
instructions supplied with the
sensor.
Clean glass bulb as per
instructions supplied with the
sensor.
Flick the sensor to remove
bubble.
Check connectors. Replace if
necessary.
Ensure that the bulb AND the
reference junction are fully
immersed.
Rinse electrolyte chamber with
warm distilled water until
dissolved.
6.2 Temperature Troubleshooting
Symptom
Possible Causes
Remedy
Meter reads
“-1 ” in
Temperature mode.
Temperature sensor is
connected, but is faulty.
Check the temperature sensor
connector and replace if
necessary.
Replace temperature sensor
(part no 121245) if problem
persists.
Temperature
readings do not vary
and Manual Temp
control is active
when temperature
sensor is plugged in.
1. Faulty connector.
2. Incorrect temperature
sensor.
3. Faulty temperature sensor.
Check the connector and
replace if necessary.
Fit new temperature sensor, part
number 121245.
Fit new temperature sensor, part
number 121245.
Temperature
inaccurate and
cannot be
calibrated.
1. Faulty connector.
2. Faulty temperature sensor.
Check the connector and
replace if necessary.
Fit new temperature sensor, part
number 121245.

Page 12
7. Appendices
7.1 pH Buffer Values Vs Temperature
The following table lists the pH values of some popular buffers, with respect to
Temperature. Any pH meter should always be calibrated to the correct value of
the buffers at the current solution temperature.
Buffer temperature should not exceed 50oC during calibration.
Temp OC
pH4.01
pH6.86
pH7.00
pH9.18
pH10.01
0
4.00
6.98
7.13
9.46
10.32
5
4.00
6.95
7.09
9.40
10.25
10
4.00
6.92
7.06
9.33
10.18
15
4.00
6.90
7.04
9.28
10.12
20
4.00
6.88
7.02
9.23
10.06
25
4.01
6.86
7.00
9.18
10.01
30
4.01
6.85
6.99
9.14
9.97
35
4.02
6.84
6.98
9.10
9.93
40
4.03
6.84
6.97
9.07
9.89
45
4.04
6.83
6.97
9.04
9.86
50
4.05
6.83
6.97
9.01
9.83

Page 13
7.2 pH Sensor Fundamentals
A combination pH sensor is two sensors in one. The sensing membrane is the
round or spear shaped bulb at the tip of the sensor. This produces a voltage that
changes with the pH of the Solution. This voltage is measured with respect to the
second part of the sensor, the reference section. The reference section makes
contact with the sample solution using a salt bridge, which is referred to as the
reference junction. A saturated solution of KCl is used to make contact with the
sample. It is vital that the KCl solution has an adequate flow rate in order to
obtain stable, accurate pH measurements.
7.2.1 Asymmetry of a pH Sensor
An “ideal” pH sensor produces 0 mV output at 7.00 pH. In practice, pH sensors
generally produce 0 mV output at slightly above or below 7.00 pH. The amount
of variance from 7.00 pH is called the asymmetry. Figure 7-1 illustrates how
asymmetry is expressed.
Figure 7-1
-600
-400
-200
0
200
400
600
0
7
14
+1.00 pH Asymmetry
0.00 pH Asymmetry
-1.00 pH Asymmetry
Response of pH Electrode, as a Function of Asymmetry
Electrode Response
pH

Page 14
7.2.2 The Slope of a pH Sensor
As mentioned above, a pH sensor produces 0 mV output at around 7.00 pH. As
the pH goes up, an “ideal” pH sensor produces -59mV/pH unit at 25 oC As the
pH goes down, an ideal pH sensor produces +59mV/pH unit. In practice, pH
sensors usually produce slightly less than this. The output of a pH sensor is
expressed as a percentage of an ideal sensor. For example, an ideal sensor that
produces 59mV/pH unit has “100% Slope”. An sensor that produces
50.15mV/pH unit has “85% Slope” (see Figure 7-2).
-600
-400
-200
0
200
400
600
0 7 14
85%Slope at 25 oC
(50.15mV/pH)
100%Slope at 25 oC
(59mV/pH)
Response of pH Electrode, as a Function of Slope
Electrode Response (mV)
pH
Figure 7-2

Page 15
7.2.3 Temperature Compensation
The slope of a pH sensor (section 7.2.2) is affected by temperature. This effect is
compensated for either by using an Automatic Temperature Compensation
(ATC) sensor or by entering the sample temperature manually. Figure 7-3 shows
the slope of a pH sensor at various temperatures.
-600
-400
-200
0
200
400
600
0 7 14
Electrode
Potential (mV) at
0 oC (54mV/pH)
Electrode
Potential (mV) at
50 oC (64mV/pH)
Electrode
Potential (mV) at
100 oC (74mV/pH)
pH Electrode Response, as a Function of Temperature
Electrode Response (mV)
pH
Figure 7-3

Page 16
8. Warranty
TPS Pty Ltd guarantees all instruments and sensors to be free from defects in
material and workmanship when subjected to normal use and service. This
guarantee is expressly limited to the servicing and/or adjustment of an instrument
returned to the TPS Pty Ltd Factory Service Centre, freight prepaid, within
twelve (12) months from the date of delivery, and to the repairing, replacing, or
adjusting of parts which upon inspection are found to be defective. Warranty
period on sensors is six (6) months.
Freight costs to and from the factory are the responsibility of the purchaser.
Shipping damage is not covered by this warranty.
TPS Pty Ltd accepts no liability for any incidental or consequential damages
caused by or resulting from the use or misuse of this equipment either due to
failure of the equipment, incorrect calibration, incorrect operation, or from
interpretation of information derived from the equipment. Specifications are
subject to change without notice. This warranty becomes invalid if modifications
or repairs are carried out on this unit by unauthorised persons. There are no
express or implied warranties which extend beyond the face hereof.
Procedure for Service
Please read service details on our ‘Service’ web page first:
http://www.tps.com.au/service.htm
TPS Pty Ltd has a reputation for prompt and efficient service. If you feel that
this equipment is in need of repair, please re-read the manual. Sometimes,
instruments are received for "repair" in perfect working order. This can occur
where batteries simply require replacement or re-charging, or where the sensor
simply requires cleaning or replacement.
Return the instrument AND ALL SENSORS to TPS Pty Ltd freight pre-paid. It
is your responsibility as the sender to ensure that TPS Pty Ltd receives the unit,
so consider using a traceable freight service.

Page 17
Please check that the following is enclosed with your equipment:
A TPS ‘Service / Return Goods Form’ –see web link below:
http://www.tps.com.au/Service/Service%20form_web.pdf
Your full name
Your company name
Your email address or fax number
Your return street address
A description of the fault. (Please be specific - "Please Repair" does
not describe a fault.)
Your equipment will be repaired and returned to you by express air freight
where possible.
For instruments beyond warranty period, a repair cost will be calculated from
parts and labour costs and emailed to you. If you decline to have the
equipment repaired, the complete instrument will be returned to you freight
paid, not serviced.
TPS Pty Ltd has only one service location, which is located at our factory in
Brisbane:
Service Department
TPS Pty Ltd
Unit 6 / 253 Leitchs Road
Brendale, QLD 4500
Australia
T: [phone]
F: [phone]
E: [email protected].au
W: www.tps.com.au