TPS pH Cube User manual

Congratulations !
You have purchased the latest in benchtop pH-mV-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
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 Site : www.tps.com.au
Model pH Cube
pH-mV-Temp.
Meter
Handbook Version : 1.1
Date : 17-May-05
Author : AB

Page 1
Contents
1. Introduction..................................................................................................2
1.1 pH Cube Front Panel and Controls........................................................................2
1.2 pH Cube Side Panel and Connectors .....................................................................3
1.3 Unpacking Information..........................................................................................4
1.4 Specifications.........................................................................................................4
2. Operating Modes..........................................................................................5
3. pH Calibration...............................................................................................6
3.1 Calibration Procedure ............................................................................................6
3.2 Calibration Notes...................................................................................................7
4. mV Calibration..............................................................................................7
5. Temperature Calibration .............................................................................8
5.1 Calibration Procedure ............................................................................................8
5.2 Calibration Notes...................................................................................................8
5.3 Manual Temperature Setting..................................................................................8
6. Troubleshooting...........................................................................................9
6.1 pH and mV Troubleshooting .................................................................................9
6.2 Temperature Troubleshooting..............................................................................10
7. Appendices.................................................................................................11
7.1 pH Buffer Values Vs Temperature......................................................................11
7.2 pH Sensor Fundamentals .....................................................................................12
7.3 Checking the reference junction of a pH sensor. .................................................14
7.4 Determining if an instrument or sensor is faulty..................................................15
8. Warranty......................................................................................................16

Page 2
1. Introduction
1.1 pH Cube Front Panel and Controls
Display
•12.7mm LED display with mode enunciator.
Function Switch
•Switches between pH, mV and Temperature modes. See section 2.
Calibrate Control
•Used for pH asymmetry calibration in pH6.88 or pH7.00 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. pH4.00, pH9.23 or pH10.00. 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 3
1.2 pH Cube Side Panel and Connectors
pH / mV Connector
•Used to connect pH, Redox (ORP) and Specific Ion sensors.
Ref Connector
•Used to connect Reference sensor when a mono pH, Redox (ORP) 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 4
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-mV-Temperature Instrument 121122
2. Combination pH Sensor 121207
3. Temperature/ATC Sensor 121245
4. pH6.88 Buffer, 200mL 121306
5. pH4.00 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
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 Ω
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 5
2. Operating Modes
Switch the function switch to any one of the following three operating modes.
Note the mode enunciator – Pfor pH, Efor EMF (mV), and Cfor OC.
Function Switch
Position Display example
pH
mV
Temp

Page 6
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. pH6.88 or pH7.00). 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 7
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. pH4.00,
pH9.23 or pH10.00) 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.
NOTE: pH9.23 and pH10.00 buffers are highly unstable. Avoid using
these buffers if possible. 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 pH6.88 or pH7.00
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. mV Calibration
The mV section is factory calibrated. There is no user-calibration facility for this
mode.

Page 8
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 9
6. Troubleshooting
6.1 pH and 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 pH6.88 or
pH7.00 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.