EDT directION GP353 User manual

Table of Contents
Section 1 - Introduction and Set Up
Section 2 - pH Calibration & Measurement
Section 3 - mV Calibration & Measurement
Section 4 - Use of the Recorder Output
Section 5 - Troubleshooting
Section 6 - Specification
Appendix 1 - pH Electrodes & Buffers
GP353 - General Purpose pH Meter - Users Manual

SECTION 1 - Introduction
Description
The GP353 is a simple-to-operate, bench pH meter. The meter can be calibrated to
one or two points, offers manual or automatic temperature compensation and
can be used to measure pH, mV and temperature.
Unpacking
Verify that you have received all equipment. If you have any questions about the
shipment, please call EDT Direct ION Ltd. or your agent.
When you receive the shipment, inspect the container for any signs of damage.
Note any evidence of rough handling in transit. Immediately report any damage to
the agent.
Note
The carrier will not honour any claims unless all shipping material is saved for
their examination. After examining and removing contents, save packing material
in the event that re-shipment be necessary.
The following items are packed in the box:
GP353 Meter E8050 Temperature Probe E8060 Electrode Stand
AC Adapter 9V Battery pH Buffers 4,7,10 Operator’s Manual
Setting Up - AC Operation
Only use the approved power adaptor supplied
Check that the adaptor is the correct voltage for your power supply
Plug the adaptor into the power socket at the back of the meter, then connect to
the AC supply.
Battery Installation
Approximately 24 hours of continuous use is afforded by the 9V battery.
The BAT flag appears on the display to indicate a low battery.
To install or replace the battery, slide off the back cover
Remove the old battery and insert a new one ensuring that the polarity is correct
Replace back cover.
Figure 1. Bottom view of instrument
showing power connections

Instrument Test Procedure
1. Ensure that the shorting plug is connected to the BNC pH input at the back of
the meter and that the temperature probe is removed.
2. Switch the Mode dial to pH mode
3. The displayed reading should lie between 6.00 and 8.00pH units
4. Adjust the Cal control until the display reads 7.00pH and remains stable.
5. The meter is ready for calibration
A Note on Electrodes
Combination pH electrodes (reference and sensing electrode in one body) or two
half-cells (reference and sensing electrodes separate) may be used with the
GP353. Combination or pH half-cells should have a BNC terminal and be
connected to the socket marked pH input at the back of the meter. Reference
half-cells should have a 4mm bunched terminal and be connected to the socket
marked REF. Always refer to electrode instructions before use. See also,
Appendix 1.
pH Buffers
See Appendix 1
Figure 2. Rear view of GP353

Section 2 - pH Calibration and Measurement
For accurate results, stir all buffers and samples. Always rinse electrodes and blot dry
before transferring from one solution to another to prevent contamination. Ensure that any
electrode filling holes are left uncovered during use.
Automatic Temperature Compensation
1. Connect the pH electrode(s) and temperature probe and turn the mode switch to °C
2. Place the pH electrode(s) and the temperature probe in the first buffer, and note the
temperature of the solution. Refer to the temperature chart on the buffer (or see
Appendix 1) and note the correct value of the buffer at the noted temperature.
3. Turn the mode switch to pH mode. Wait for the reading to stabilise. Using the CAL
control, adjust the reading to the value obtained in step 2.
4. Place the pH electrode(s) and temperature probe in the second buffer. Again establish
the correct value for the temperature of measurement. When the reading is stable,
adjust to the correct value using the Slope control.
5. Automatically temperature compensated readings may now be made by immersing the
pH electrode(s) and temperature probe into the sample and recording the stabilised
reading.
Manual Temperature Compensation
If use of a temperature probe is inappropriate (e.g. small sample size), then it is possible to
use manual temperature compensation).
1. Disconnect temperature probe.
2. Measure the temperature of the buffer with a thermometer.
3. Switch to °C mode and adjust the reading to the correct value using the Temp °C control.
4. Refer to the temperature chart on the buffer (or see Appendix 1) to establish the correct
buffer value for the temperature of measurement.
5. Follow the procedure given above for Automatic Temperature Compensation, points 3.
to 5. above, measuring and adjusting the temperature manually for each buffer and
sample.
No Temperature Compensation
For accurate results with no temperature compensation, the temperature of all buffers and
samples should be equal and remain constant.
1. With the temperature probe disconnected, switch the instrument to °C mode and set the
displayed reading to the temperature of measurement using the Temp °C control.
2. Switch to pH mode, place the electrode(s)in the first buffer, wait for the reading to
stabilise and enter the correct value (given on the buffer packet or in Appendix 1) using the
CAL control.
3. Place the electrode(s) in the second buffer. When the reading is stable, adjust to the
correct value using the Slope control.
4. Place the electrode(s) in the sample and record the stabilised reading.

Section 3 -
Section 4 -
Section 5 -
No attempt should be made to repair the meter.
mV Calibration and Measurement
Absolute mV
1. Switch the mode dial to mV
2. Connect the shorting plug to the BNC input and adjust the CAL control until the display
reads 000mV
3. Remove shorting plug and connect electrode(s).
4. Absolute mV readings may now be made by immersing the electrodes in the sample
and recording the reading.
Relative mV
1. Switch the Mode dial to mV
2. Connect electrode(s)
3. Immerse electrode(s) in the standard or blank solution and adjust the CAL control until
the display reads 0mV. (Note, the maximum offset is 60mV).
4. mV values relative to the standard solution may now be taken by immersing in the
sample and recording the reading.
Use of the recorder output
1. Connect the recorder via the red and black 4mm sockets on the back panel. (Red
positive, Black negative)
2. Ensure that the recorder is set for the appropriate range, as shown below.
MODE RANGE (mV) DISPLAY RECORDER
pH 0-200 7.00pH 70.0mV
mV ±200 500mV 50.0mV
°C ±200 25.0°C 25.0mV
Troubleshooting
In the event of a malfunction, it is important to pinpoint the problem to either the meter
or the cell. If a spare cell is available, substitute it for the one in use.
There are no user serviceable parts in this instrument. Please ensure that the instrument,
together with all accessories, is returned to EDT Direct ION Ltd or the agent with a full
description of the symptoms.

Section 6 - Specifications
Symptom
Probable Cause
No display
Battery is flat or not installed
Power supply disconnected
‘BAT’ flag displayed
Battery Low
Wildly erratic readings or display reads --
on left hand side
Electrodes disconnected
Electrodes not immersed in solution
Reference electrode not filled
Reference junction dry
Drifting readings
Inconsistent or lack of stirring
Reference filling solution contaminated
Buffers contaminated
Erratic/drifting readings or display reads –
on left hand side when shorting plug is
attached.
Return meter for servicing
pH Range -2 to 19.99
pH Resolution 0.01pH
pH Accuracy ±0.02pH
Temperature Compensation 0-100°C
Manual Calibration 2 points at any value
mV Range ±2000mV
mV Resolution 1mV
mV Accuracy ±2% ±1 digit
°C Range -100 to +200°C
°C Resolution 0.1°C
°C Accuracy ±0.5°C
Recorder Output 0-200mV
Karl Fischer Output 10µA
Display
Power
-
Instrument Size
Instrument Weight
12.7mm LCD
9V Battery or AC
210 x 150 x 88mm
550g

Appendix 1 - pH electrodes
Before Use
Remove the protective cap covering the glass sensing bulb and replace with the
protective guard if applicable. Inspect the filling solution for air bubbles and remove
by shaking in a downward direction. Soak the electrode in pH storage solution for 30
minutes.
Cleaning
Soak the electrode in 0.1M HCl for 15 minutes followed by soaking in pH storage
solution for 30 minutes
Storage.
Put some pH storage solution in the protective cap and place over the glass bulb.
Never store the electrode in distilled or de-ionised water. Never allow the electrode to
dry out.
pH electrode storage solution is made up by dissolving 1g KCl in 100mL of pH 7 buffer
pH Buffers - Buffer Capsules
Buffer capsules are made up as follows For each buffer, empty the powder into a
suitable container. Using deionised water, make up to 100mL ensuring that the
powder is filly dissolved before use. The coloured outer skin may be added to colour
code the resulting buffer. This may take up to 4 hours to dissolve but will not affect
the pH of the buffer.
Buffer Solutions
If using ready made solutions, use ones supplied with temperature coefficient
information.
Table of Temperature Coefficients For EDT Buffers
°C pH 4 pH 7 pH pH10
10 3.99 7.07 10.18
15 4.00 7.04 10.14
20 4.00 7.02 10.06
25 4.00 7.00 10.00
30 4.00 6.99 9.95
35 4.01 6.98 9.91
40 4.02 6.97 9.85
50 4.05 6.96 9.78
60 4.07 6.96 9.75

For more information on our products
please visit our website www.edt.co.uk
EDT directION
Unit 5 Waldershare Park, Dover. CT15 5DQ.
Telephone: [phone] Email: [email protected]
Company No, 04135318 VAT No. GB 765175410