IQ Scientific Instruments IQ240 User manual

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MODEL IQ240 pH Meter
Getting Started
TWO-POINT CALIBRATION--QUICK REFERENCE GUIDE
1. 2. 3. 4.
Connect probe to
meter. Put probe in first calibrating buffer. Press ON/OFF to turn on meter. If necessary, press pH until pH status
indicator arrow
points to pH. Status
indicator arrow
should NOT point to
BUFFER.
5.
6. 7. 8.
Press CAL, then
CLEAR to clear the
previous calibration.
Status indicator
arrow will point to
1PT.
Meter will automatically
identify the first buffer
solution. If necessary,
press SELECT
BUFFER until display
matches first buffer
value.
Press ENTER and
wait until the large
number display
stops flashing.
Rinse probe in
deionized water and
place in second
calibrating buffer.
9. 10. 11. 12.
Press CAL. Status
indicator arrow will
point to both 1PT
and 2PT.
Meter will automatically
identify the second
buffer solution. If
necessary, press
SELECT BUFFER
until display matches
second buffer value.
Press ENTER and
wait until the large
number display
stops flashing.
Rinse probe in
deionized water and
place in sample.

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INTRODUCTION
IMPORTANT NOTICE
IF THE METER IS USED IN A MANNER OTHER THAN AS
DESCRIBED, THE SAFETY AND PERFORMANCE OF THE METER
CAN BE IMPAIRED.
This system uses an Ion Sensitive Field Effect Transistor (ISFET) pH sensor.
There is no glass to break and the probe should be stored dry. No electrode
storage solution is required. The “3-in-1” probe contains the pH sensor,
reference electrode, and temperature sensor.
ESTIMATED LIFE OF AN ISFET SENSOR pH PROBE
Depending upon the application, the expected life of an ISFET probe is
approximately 18 months. The reference electrode contains a KCl gel that
becomes increasingly diluted with usage and time. The reference is sealed
and is not refillable. When it becomes difficult to calibrate (pH buffer value
does not stop flashing during calibration or takes an excessively long time to
stop flashing) the probe should be replaced. A probe that is dirty,
miscalibrated, or has reached the end of its useful life will give an error
message E11 on the meter display. Your ISFET probe is warranted to be free
from manufacturing defects for six (6) months from the date of purchase.

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Table of Contents
Getting Started--
Quick Reference Guide for Two Point Calibration. . . . . . .
1
Techniques and Tips For Best Performance. . . . . . . . . . . . . . . . . . . . . . 4
Display Features and Meter Connections. . . . . . . . . . . . . . . . . . . . . . . . 6
Main Display. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Meter Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Status Indicators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Keypad Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Cleaning and Reconditioning the Probe. . . . . . . . . . . . . . . . . . . . . . . . . 11
pH Calibration and Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Important Notes for Best Calibration Results. . . . . . . . . . . . . . . . . . . 13
Calibration With Two Buffers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Calibration With Three Buffers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Calibration With One Buffer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
How to AbortCalibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Automatic Buffer Recognition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Automatic Temperature Compensation of Automatic Buffer
Recognition Values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Changing Stored Automatic Buffer Recognition Values. . . . . . . . . . 17
Restoring Automatic Buffer Recognition Values to Factory Default. 18
mV Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Titrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storing and Recalling Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 20
Storing Sample Readings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Recalling Sample Readings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Clearing Data from One Storage Address. . . . . . . . . . . . . . . . . . . . . . 21
Clearing Data from All Storage Addresses. . . . . . . . . . . . . . . . . . . . . 21
Output Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
AnalogOutput. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Serial Output. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Output of Calibration Data to the Serial Port. . . . . . . . . . . . . . . . . . . 23
Output of Current Sample to the Serial Port. . . . . . . . . . . . . . . . . . . . 23
Output of the Contents of a Single Memory Address . . . . . . . . . . . . 23
Output of the Contents of all Memory Addresses . . . . . . . . . . . . . . . 23
Setting the Baud Rate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Temperature Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
User Temperature Calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Restoring Temperature Calibration to Factory Default. . . . . . . . . . . 24
Battery Replacement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Error Codes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

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Techniques and Tips for Best Performance
DO
DO: Soak the probe in pH 7.00 buffer for at least five minutes if the probe is
new or has been stored dry for an extended period. This will hydrate the
sensor and dissolve any reference material, which may have crystallized on
the sensor surface.
DO: Clean the probe regularly with a toothbrush and mild detergent.
DO: STORE THE PROBE DRY with the black protective cap covering the
probe tip. No electrode storage solution is required.
DO: Always begin each measuring session with a two-point calibration.
Update often with one-point or two-point calibrations.
DO: Use fresh buffers and deionized rinse solution.
DO: Use buffer solutions with pH values no greater than three pH units apart.
Buffers should bracket the anticipated values of the samples to be measured.
DO: Choose buffer solutions that most closely mimic the chemical nature and
conductivity level of the sample solutions to be measured.
DO: Use deionized water to rinse residual buffer and sample solutions from the
probe after calibration and measurement.
DO: Calibrate at the same temperature as the sample solution. Although the
meter has automatic temperature compensation, best results will be achieved if
the calibration buffers and sample are the same temperature.
DO: Keep the connectors clean and dry. Dirty or damp connectors can cause
unstable readings.
DO: Be sure the surface of the sensor in the probe is free from any deposits or
films. See the cleaning instructions in this manual.
DO: Contact IQ Scientific Instruments if your pH testing involves monitoring
small pH changes over time (i.e. titrations).

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DO NOT
DO NOT: change probes while the meter is turned on. Always turn off the
meter before changing probes.
DO NOT: store the probe in solution or use for long-term pH measuring
applications. Extended immersion will shorten the life of the probe.
DO NOT: leave probe uncapped for long periods of time. Always place the
protective cap over the probe tip when finished measuring.
DO NOT: allow oil, fat, food particles, starch, protein, or other materials to
remain on the probe tip after use.
DO NOT: use a sharp metal object (needle, pin, etc.) to clean the sensor
surface.
DO NOT: take readings in direct sunlight. Direct sunlight may cause unstable
readings or difficulty in calibration. Call IQ Scientific Instruments or your
Authorized Dealer for optional light shields.
DO NOT: use the probe in an environment that will damage the pH sensor,
such as hydrofluoric acid or abrasive samples.
DO NOT: use the probe in environments that will damage the epoxy
materials used in probe construction, such as, acetone, toluene, methylene
chloride, xylene, and other strong organic solvents.
DO NOT: use the probe in environments with static electricity. Electrostatic
discharge may permanently damage the probe.
DO NOT: expose the ISFET probe to repeated temperature extremes (60 oC or
higher). Do not use the probe for applications that require the probe to cycle
between hot and room temperature samples.
DO NOT: put any other active measurement devices in buffers or samples
while measuring pH. Even if another device is not actually turned on, AC
power interference can still occur, especially if the pH meter AC battery
adapter is in use.

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Display Features and Meter Connections
1. Main Display
2. Temperature Display.
3. AUTO HOLD Mode Indicator
4. Status Indicator Arrows
5. Serial Interface (RS-232)
6. AC Adapter Connector
7. Recorder Output
8. Probe Connector
Main Display
The large digits show the following:
1. Readout of the measured value, either pH or millivolt.
2. Memory address display “AXX” indicates memory location,
where XX is a number from 01 to 20. For example: A03
indicates memory address 03 is in use.
3. Error Codes “EXX” where XX = a number. For example: E11
indicates a calibration error. See the troubleshooting section of
this manual for details on error codes.
Temperature Display
The small digits display temperature in oC. The display is accurate only when
the probe is in solution. The temperature sensor can be calibrated by the user
(See Page 24).
AUTO HOLD (eye icon) Indicator
This mode allows a reading to remain automatically locked on the display for
future reference. The eye symbol indicates that the meter is in the automatic
hold “AUTO HOLD” mode. The eye symbol starts flashing when the meter
begins to take a reading and stops flashing (locks) when the reading has
stabilized. The reading remains locked until the pH key is pressed to unlock
the reading or the HOLD key is pressed to exit the AUTO HOLD mode.

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Meter Connections
RS-232 Standard 9 pin connector for serial output to printer or
computer.
AC Power Adapter to attach the provided AC adapter.
Analog Recorder Output for a chart recorder.
Probe Connector Jack for connection of pH probe to meter.
pH Indicates that the meter is in the pH mode. Flashing pH
arrow indicates that the meter is still seeking a stable
reading. Stable pH arrow indicates that a stable reading
“endpoint” has been reached.
mV Indicates that the meter is in the Millivolt mode.
REL mV Indicates that the meter is in the Relative Millivolt
mode.
BUFFER Indicates that the meter is in the Select Buffer mode.
1 PT Indicates that one buffer value has been used for
calibration. If flashing, first buffer has been selected
but not read.