EUTECH INSTRUMENTS ALPHA PH 500 PHORP 2-WIRE TRANSMITTER (REVISION... User manual

Instruction Manual
pH 500 LCD Transmitter
2-wire pH/ORP Transmitter with Display
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68X216829
03/02 version 1

Preface
This manual serves to explain the use of the pH 500 transmitter. It functions in two
ways, firstly as a step by step guide to help you to operate the transmitter.
Secondly, it serves as a handy reference guide. It is written to cover as many
anticipated applications of the transmitter as possible. If there are doubts in the use
of the transmitter, please do not hesitate to contact the nearest Authorized
Distributor.
Eutech Instruments/ Oakton Instruments will not accept any responsibility for
damage or malfunction to the transmitter caused by improper use of the instrument.
Remember to fill in the guarantee card and mail it back to your authorized
distributor or Eutech Instruments Pte Ltd.
The information presented in this manual is subject to change without notice as
improvements are made, and does not represent a commitment on the part of
Eutech Instruments Pte Ltd/ Oakton Instruments.
Copyright © 2002 Updated on Mar 2002. All rights reserved.
Eutech Instruments Pte Ltd/ Oakton Instruments

TABLE OF CONTENTS
1INTRODUCTION 1
2PREPARATION 2
2.1 Power Supply Requirements 2
2.2 Connecting the Electrode and Temperature Probe 3
3INSTALLATION 4
3.1 Wall Mount 4
3.2 Panel Mount 5
4DISPLAY AND KEYPAD FUNCTIONS 6
4.1 Display 6
4.2 Keypad 7
5CALIBRATION 8
5.1 Preparing the Transmitter for Calibration 8
5.2 pH Calibration 9
5.3 Relative mV Calibration 10
5.4 Temperature Calibration 10
6ADVANCED SETUP FUNCTIONS 11
6.1 Offset Setting (Unavailable in ORP mode) 11
6.2 Output Range Setting 12
6.3 Temperature Compensation Setting (Unavailable in ORP mode) 13
6.4 HOLD Current Setting 15
6.5 Out-of-Range Current Setting 15
6.6 Configuration 16
7PROBE CARE AND MAINTENANCE 17
8TROUBLE SHOOTING GUIDE 19
9SPECIFICATIONS 20
10 TECHNICAL DIMENSIONS 21
11 ACCESSORIES 22
12 WARRANTY 24
13 RETURN OF ITEMS 24

1
1 INTRODUCTION
Thank you for selecting a Eutech Instruments/ Oakton Instruments transmitter. The
pH 500 pH/ORP Transmitter is a microprocessor-based instrument that is designed
to be sturdy and user-friendly. It is capable of measuring pH, mV and temperature.
This transmitter has many user-friendly features – all of which are completely
accessible through the water-resistant membrane keypad. Your transmitter includes
an instruction manual and a warranty card.
Please read this manual thoroughly before operating your transmitter.
MEAS
癈
READY
.
.
A
TC
pH

2
Preparation
Remove screws from the four corners at the back of the Transmitter, and remove
back cover.
Connectors should be exposed as follows:
All wiring is done on the detachable 9-pin connector. Using a suitable screwdriver,
loosen screws from top of connector.
When inserting the wires, always hold connector with top screws facing up.
1.1 Power Supply Requirements
This transmitter requires a 12 to 24V DC power supply. Other Transmitters and/or a
chart recorder may be connected in series.
Insert positive loop wire from power supply to pin 1, tighten screw.
Insert negative loop wire to pin 2, tighten screw. This wire may be linked to the
positive terminal of next transmitter (pin 1) / Chart recorder or to negative terminal
of power supply.

3
1.2 Connecting the Electrode and Temperature Probe
To connect the pH or ORP electrode:
The Eutech Instruments pH transmitter uses any
standard pH or ORP.
Remove BNC connector from cable. Two wires
will be exposed:
Strip insulation, just enough to expose bare wires.
IMPORTANT: For pH/ORP sensing cable, remember to strip the inner black
layer (screen) and expose the clear plastic sheath.
Insert pH sensing cable into pin 9 of connector. Tighten screw.
Insert pH reference cable into pin 7 of connector. Tighten screw.
To connect temperature probe:
For Automatic Temperature Compensation (ATC), this transmitter requires a
temperature probe, Pt 100, 3-wire.
3-wire probe:
Insert brown wire to pin 4 of connector. Tighten screw.
Insert red wire to pin 5 of connector. Tighten screw.
Insert green wire to pin 6 of connector. Tighten screw.
2-wire probe:
Take a small length of wire and short pins 4 and 5 of connector. Insert red wire into
pin 5 of connector and tighten screws.
Insert green wire to pin 6 of connector. Tighten screw.
IMPORTANT: Temperature probe should always be together with pH probe,
even during calibration. Make sure no bare wires are exposed and all screws
are tightened for proper contact.
To connect Potential Matching Pin (Liquid electrical interferences):
Connect the additional wire from the electrode to pin 3. Transmitter must be
configured to ‘Symmetrical mode of operation’ - Please refer to ‘Advanced Setup
Functions’, Section 6.6.2 - ‘Selecting Asymmetrical or Symmetrical Mode of
Operation.
Insulation
pH reference
Clear sheath
pH sensing
Screen

4
2 INSTALLATION
2.1 Wall Mount

5
2.2 Panel Mount
1. Prepare panel cut-out of
92.0 mm by 92.0 mm
2. Remove back cover of
transmitter and slide it
through panel cut-out
Panel (side)
3. Attach lugs to either
side of transmitter
4. Thread rods through
lugs until transmitter
is held in place against
panel

6
3 DISPLAY AND KEYPAD FUNCTIONS
3.1 Display
The LCD has a primary and secondary display.
•The primary display shows the measured pH, mV or Relative mV
value.
•The secondary display shows the measured temperature. In
Calibration mode, pH buffer values are displayed here; while
measured mV values are displayed in the ORP Calibration mode.
SETUP MEAS CAL
HOLD
pH
癈
READY
-.8.8.8
-1.8.8.8
ATC
pH
mV
ERR
123
4
5
6
7
8
9
10
1112
13
14
15
1. SETup mode indicator 6. Primary display 11. ERRor indicator
2. MEASurement mode indicator 7. Temperature indicator 12. Probe indicator
3. CALibration indicator 8. pH buffer selection indicator
13. Buffer indicator
4. mV indicator 9. Automatic Temperature Compensation
indicator
14. HOLD indicator
5. pH indicator 10. Secondary display 15. READY indicator

7
3.2 Keypad
The four-button keypad allows easy and quick operations of the Transmitter.
Key Function
CAL Brings you directly into the Calibration mode.
1. If you were in pH Measurement mode, press CAL to enter pH
Calibration mode.
2. If you were in mV Measurement mode, press CAL to enter mV
Calibration mode.
▲/▼1. To scroll through the various submenus
2. To increment/decrement values or toggle between options (in
the SETUP/CAL modes)
3. When pressed together, serves as escape function to return to
MEAS mode from any point (CAL or SETUP modes).
ENT 1. To confirm your calibration values in Calibration mode.
2. To confirm selections in SETUP mode.
While in MEAS mode, pressing ENT takes you directly to SETUP
submenu

8
4 CALIBRATION
4.1 Preparing the Transmitter for Calibration
Before starting calibration, make sure you are in the correct measurement mode.
When you switch on the transmitter, the transmitter starts up in the units last used.
For example, if you shut the transmitter off in “mV” units, the transmitter will read
“mV” units when you switch the transmitter on.
Be sure to remove the protective electrode storage bottle or rubber cap of the
electrode before calibration or measurement. If the electrode has been stored dry,
wet the electrode in tap water for 10 minutes before calibrating or taking readings to
saturate the pH electrode surface and minimize drift.
Wash your electrode in deionized water after use, and store in electrode storage
solution. If storage solution is not available, use pH 4.01 or 7.00 buffer solution.
Do not reuse buffer solutions after calibration. Contaminants in the solution can
affect the calibration, and eventually the accuracy of the measurements.
The transmitter features two internationally recognized buffer standards. Select the
buffer standard you require in the CAL mode Select from the following buffer
options:
•First-point : pH 7.00 (USA buffer) or pH 6.86 (NIST buffer).
•Second point: pH 4.01, 9.18, or 10.1.
NOTE: When transmitter is entered into the CAL mode, the 4/20 mA output current will
be automatically held*. ‘HOLD’ will be displayed on LCD. After Calibration and
transmitter is returned to MEAS mode, the ‘HOLD’ is automatically released.
* Please refer to page 14, section 6.4 for more details.

9
4.2 pH Calibration
A complete 2-point CAL is required for this Transmitter. If Calibration is
aborted after 1st calibration point, transmitter reverts to previous
Calibration data.
1. Rinse probe thoroughly with de-ionized water or a
rinse solution. Blot excess liquid.
2. Dip probe into calibration buffer. End of probe must be
completely immersed into buffer. Stir probe gently to
create a homogeneous sample.
3. From pH MEAS mode, press CAL to enter pH
calibration mode. CAL indicator will be shown. Primary
display will show measured reading while secondary
display will indicate the pH standard buffer solution.
4. Press
▲or ▼keys to select either pH 7.00 (USA) or
pH 6.86 (NIST) standard buffers. This is the first point,
Offset calibration.
5. Wait for measured pH value to stabilize. Press
ENTER to confirm calibration. Transmitter is now
calibrated to current buffer.
6. Rinse probe with de-ionized water or rinse solution,
and place in next pH buffer (pH 4.01, pH 9.18 or pH
10.01).
7. Repeat steps 5 and 6.
8. Upon successful Calibration, transmitter displays
Slope (primary display, in mV) and Offset (secondary
display, in pH) of electrode.
9. Press ENTER to return to MEAS mode. Transmitter
has been calibrated. Rinse electrode and proceed
with measurements.
NOTES:
To exit from pH calibration mode without confirming calibration, press
▲ and ▼ keys
together.
If selected buffer value is not within ±1.0 pH from measured pH value: electrode and buffer icon blink
and ERR annunciator appears in lower left corner of display.
CAL
HOLD
pH
READY
.
.
pH
CAL
HOLD
pH
READY
.
.
pH
CAL
HOLD
pH
READY
.
.
pH
CAL
HOLD
pH
.
.
mV

10
4.3 Relative mV Calibration
1. From the ORP MEAS mode, press CAL key.
CAL indicator appears at top of LCD. Primary
display shows relative mV reading and
secondary display shows absolute mV value.
NOTE: If you have never calibrated relative mV
or if the transmitter has been reset, the value
shown in the primary display is the same as the
absolute mV value.
2. Press
▲or ▼keys to enter the relative mV value
that matches your desired reading (only the
readings in the primary display changes).
3. Press ENTER key to confirm. Transmitter will
now display the offset in the readings.
4. Press ENTER key to return to MEAS mode.
4.4 Temperature Calibration
Only available in the pH mode and ATC probe is available.
Calibrate temperature probe only if temperature value displayed on transmitter is
different from that of a calibrated thermometer. Temperature readings are only
displayed
Please refer to section 6.3.1 for further information.
CAL
HOLD
READY
R.mV
CAL
HOLD
READY
CAL
HOLD
READY
R.mV
R.mV

11
SETUP
HOLD
SETUP
HOLD
pH
READY
.
.
pH
5 ADVANCED SETUP FUNCTIONS
The advanced setup mode lets you customize your transmitter’s preferences and
defaults. This transmitter features different sub groups that organize all setup
parameters.
The sub-groups are:
5.1 Offset Setting (Unavailable in ORP mode)
As a result of the continuous measurement and the application concerned, it may
not be convenient to remove the electrode for calibration. In such cases, an on-line
Offset adjustment is offered.
1. Press ENT key. Transmitter displays ‘OFS’. Press ENT
again. Upper display shows amount of offset, in terms of pH;
lower display shows current measured pH value.
2. Use
▲or ▼keys to introduce offset to pH readings. As the
lower measured reading changes, upper display records the
amount of offset. Maximum of ± 2.00 pH offset is allowed.
3. Press both ▲or ▼keys together to return to ‘ MEAS ‘ mode.

12
SETUP
HOLD
5.2 Output Range Setting
Output of pH 500 transmitter is via the 2-wire power supply
loop. Both the 4 mA and 20 mA output can be assigned to
specific pH or ORP values, for a more refined output.
1. Press ENT key and use ▲or ▼keys to scroll till LCD
displays
‘r n g ’. Press ENT again. Upper display shows pH value,
‘0.00’ (or – 1000 mV) while lower display shows ‘r 4.0’.
2. Assign pH or ORP value to 4 mA output current. Use ▲or
▼keys to change pHor ORP value. Press ENT to accept
value.
3. Upper display shows pH value,’14.00’ (or 1000 mV) while
lower display shows ‘r 20.0’.
4. Assign pH or ORP value to 20 mA output current. Use ▲or ▼keys to change
pH or ORP value. Press ENT to accept value.
5. Press both
▲or ▼keys together to return to ‘ MEAS ‘ mode.

13
5.3 Temperature Compensation Setting
(Unavailable in ORP mode)
pH values other than pH 7.00 is affected by temperature. Under varying temperature conditions, use
ATC to compensate pH values. If temperature of bath is constant, then select Manual Temperature
Compensation.
5.3.1 Automatic Temperature Compensation
For automatic temperature compensation (ATC), connect ATC probe to transmitter, as described in
Section 3.2, page 5.
1. Press ENT key to enter SETUP mode. Press ▲or ▼keys to scroll through sub-menus till
LCD displays ‘SET oC’. Press ENT.
2. Display shows ‘ATC On’ or ‘ATC Off’. Use Sor Tkeys to select ‘ATC On’, and press
ENT.
3. Dip ATC probe into a solution of known temperature (i.e. a temperature bath). Allow time for
temperature probe to acclimatize with surrounding bath temperature. If temperature readings
are inaccurate, calibrate temperature probe as described in steps 4 and 5.
If temperature readings are correct, press ENT key and go to step 6.
4. Use Sor Tkeys to adjust correct temperature value (i.e. temp. of temp. bath). Readings can
be adjusted in increments of 0.1 °C. Maximum adjustments allowed is ± 5 oC.
5. Once you have adjusted the correct temperature, press ENT key.
6. Press Sand Tkeys together, to return to MEAS mode.
The ATC indicator will light up on the LCD.
NOTE: If you are using a temperature probe, the probe must be submersed in the
liquid you are measuring.
5.3.2 Manual Temperature Compensation
1. Make sure the transmitter is on. Press ENT key and use ▲or ▼keys to select ‘SET oC’.
2. Press ENT key. Primary display shows ‘ATC’ and secondary display shows ‘On’ or ‘OFF’.
Use ▲or ▼keys to select ‘ATC Off’. Press ENT.
3. Primary display shows temperature (default is 25.0), and secondary display shows
‘P oC’.Check temperature of your sample/process, using an accurate thermometer.

14
4. Use ▲or ▼keys to set temperature of sample. Press ENT key.
5. Primary display shows temperature (default is 25.0), and secondary display shows ‘C oC’.
Input temperature of your calibration solutions. Press ENT key.
6. Press Sand Tkeys together, to return to MEAS mode.
The transmitter will now compensate pH readings for the manually set temperature (values taken
from P oC).
SETUP
HOLD
SETUP
HOLD
SETUP
HOLD
癈
.
.
ATC
SETUP
HOLD
SETUP
HOLD
.
SETUP
HOLD
.
Temperature Compensation Setting Chart – alpha pH 500 Transmitter

15
SETUP
HOLD
SETUP
HOLD
SETUP
HOLD
5.4 HOLD Current Setting
When Transmitter is in CAL or SETUP modes, it automatically goes into a
‘HOLD’ mode.
To indicate Transmitter is in ‘HOLD’ mode, output current can be set to 22
mA output by activating the ‘HLD On’.
1. Press ENT key and use ▲or ▼keys to scroll till LCD displays
‘SEt’ in the upper display; and ‘HLd’ in the lower display. Press
ENT again.
2. Upper display now shows ‘HLd’. Lower display will show either
‘OFF’ or ‘On’. Use ▲or ▼keys to toggle between ‘On’ of ‘OFF’.
Press ENT to accept selection.
3. Press Sand Tkeys together, to return to MEAS mode.
NOTE: If ‘HLd’ is set to ‘OFF’, then current output will be equivalent to last
measured value.
5.5 Out-of-Range Current Setting
If pH or ORP readings exceed the scale, LCD displays ‘Or’ (over-range), or
‘Ur’ (under-range). Transmitter current output can be set to 3.8 mA to indicate
Out-of Range situation.
1. Press ENT key and use ▲or ▼keys to scroll till LCD displays
‘SEt’ in the upper display; and ‘org’ in the lower display. Press
ENT again.
2. Upper display now shows ‘org’. Lower display will show either ‘OFF’
or ‘On’. Use ▲or ▼keys to toggle between ‘On’ of ‘OFF’. Press
ENT to accept selection.
3. Press Sand Tkeys together, to return to MEAS mode.
NOTE: If ‘org’ is set to ‘OFF’, under-range will be set at 4 mA, while over-
range will be set at 20 mA.
SETUP
HOLD
SETUP
HOLD
SETUP
HOLD

16
5.6 Configuration
5.6.1 Selecting pH or ORP Mode of Operation
The alpha pH 500 transmitter is not only a pH transmitter, but also an ORP
transmitter. When configured to measure ORP, electrode must be changed
and calibrated (see Section 5.3 for calibration procedure). ORP values are
measured and displayed in mV only.
1. Press ENT key and use ▲or ▼keys to scroll till LCD displays
‘COF’ (Configuration). Press ENT again.
2. LCD displays ‘PH’. Transmitter is set to operate as a pH
Transmitter. Use ▲or ▼keys to change from ‘PH’ to ‘ORP’, if
this Transmitter is to operate as an ORP Transmitter.
3. Press the ENT key to accept selection.
4. Press Sand Tkeys together, to return to MEAS mode.
5. If the readings on the Transmitter is fluctuating wildly, please
proceed to Section 6.6.2, for a possible solution.
5.6.2 Selecting Asymmetrical or Symmetrical Mode of Operation
In some applications, there may be some electrical interference in the sample, where the electrode is
installed. The sensitive electrode picks up the signal and the effect is displayed on the LCD.
If the electrical interference is from an AC source, the readings on the LCD fluctuates wildly. If the
source is DC, then readings will be stable, but at a wrong value.
In such cases, switch the Transmitter to the Symmetrical mode as below:
1. Press ENT key and use ▲or ▼keys to scroll till LCD displays
‘COF’ (Configuration). Press ENT again.
2. LCD displays either ‘PH’ or ‘ORP’ depending on requirement.
Press ENT key.
3. LCD displays ‘ASY’ (asymmetrical operation). Use ▲or ▼keys
to select for ‘SYS’ (symmetrical mode of operation). Press ENT
key again.
4. Press Sand Tkeys together, to return to MEAS mode.
SETUP
HOLD
SETUP
HOLD
SETUP
HOLD
SETUP
HOLD
SETUP
HOLD

17
6 PROBE CARE AND MAINTENANCE
Since your pH electrode is susceptible to dirt and contamination, clean it every one
to three months depending on the extent and condition of use.
NOTE: For specialty electrode care, consult the instruction manual included with
your electrode.
pH electrode storage
For best results, always keep the pH bulb wet. Use the protective electrode storage
bottle or rubber cap filled with electrode storage solution to store your electrode.
Also, you can store in a pH 4 buffer with 1/100 part of saturated KCl. Other pH
buffers are OK for storage, but NEVER use distilled water for storage.
After measuring
1. Rinse the pH electrode and reference junction in de-ionized water.
2. Store the electrode as recommended above in “pH electrode storage,” or as
recommended by the manufacturer.
3. Prior to next use, rinse the liquid junction with de-ionized water and tap dry –
never wipe electrode.
NOTE: If this does not restore electrode to normal response, see “Reactivating the
pH electrode” section below.
pH electrode cleaning
•Salt deposits: Dissolve the deposits by immersing the electrode in
tap water for ten to fifteen minutes. Then thoroughly rinse with distilled
water.
•Oil/Grease film: wash electrode pH bulb gently in some detergent
and water. Rinse electrode tip with distilled water or use a general
purpose electrode cleaner (see ordering information).
•Clogged reference junction: Heat a diluted KCl solution to 60 to 80
°C. Place the sensing part of the electrode into the heated solution for
about 10 minutes. Allow the electrode to cool in some unheated KCl
solution.