IQ IQ150 User manual

1
MODEL IQ150 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 pHicon is
seen on the display.
5. 6. 7. 8.
Press CAL. If necessary, press
SELECT BUFFER
until display matches
first buffer value.
Press ENTER and
wait until the large
number display
stops flashing.
When complete,
meter will display
the next stored
buffer value. 2PT
will be displayed.
9. 10. 11. 12.
Rinse probe in
deionized water
and place in
second calibrating
buffer.
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.

2
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.
IF THE SEAL ON THE BACK OF THE METER IS TAMPERED
WITH, THE WARRANTY IS IMMEDIATELY VOIDED.
The IQ150 pH “Dual Technology” meter accepts both traditional style glass
sensor electrodes with BNC connectors as well as non-glass pH probes with
ISFET (Ion Sensitive Field Effect Transistor) silicon chip sensors.
Throughout this manual, non-glass pH probes with silicon chip sensors will be
referred to as “ISFET” probes. The meter has a standard BNC connector for
attachment of glass sensor pH electrodes. Glass sensor pH electrodes will be
referred to as “BNC” probes.
The meter is designed to use only one electrode at a time. The meter
automatically identifies which type of electrode is attached when the meter is
turned on. If both ISFET and BNC probes are attached at the same time,
errors may occur. Always turn off the meter when changing electrodes
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, which
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 E06 or E07 on the meter display. Your ISFET probe is warranted to
be free from manufacturing defects for six (6) months from the date of
purchase.

3
Table of Contents
Two-Point Calibration Quick Reference Guide . . . . . . . . . . . . . . . . . . . . . . . .1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
Techniques and Tips for Best Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Display Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Keypad Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Connecting Electrodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
pH Calibration and Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Important Notes for Best Calibration Results. . . . . . . . . . . . . . . . . . . . . . . . . . 9
Calibration with Two Buffers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Calibration with One Buffer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
How to Abort Calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Automatic Temperature Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Manual Temperature Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
mV Measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Temperature Measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Cleaning and Reconditioning ISFET Probes . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Cleaning with Detergent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Reconditioning with Warm Buffer . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Cleaning with Alcohol or Methanol . . . . . . . . . . . . . . . . . . . . . . . . . 16
Cleaning with Sodium Hypochlorite. . . . . . . . . . . . . . . . . . . . . . . . . 16
Cleaning and Reconditioning BNC Electrodes . . . . . . . . . . . . . . . . . . . . . . . . 17
Cleaning with Detergent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Reconditioning with Warm Buffer . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Cleaning with Acid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Cleaning with Methanol or Acetone . . . . . . . . . . . . . . . . . . . . . . . . .
117
Cleaning with Pepsin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Etching with Ammonium Biflouride. . . . . . . . . . . . . . . . . . . . . . . . . 18
Titrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Battery Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18
19
Automatic Shutoff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
AC Adapter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Error Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

4
Techniques and Tips for Best Performance
DO
DO: (ISFET non-glass probe ONLY) 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: (ISFET non-glass probe ONLY) Clean the probe regularly with a
toothbrush and mild detergent.
DO: (ISFET non-glass probe ONLY) STORE THE PROBE DRY with the
black protective cap covering the probe tip. No electrode storage solution is
required.
DO: (BNC probe ONLY) Store the probe in electrode storage solution.
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 pHvalues 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).

5
DO NOT
DO NOT: change probe types (switch between BNC and ISFET probes)
while the meter is turned on. Always turn off the meter before changing
probes.
DO NOT: simultaneously use ISFET and BNC probes. Only have one type
of probe attached to the pH meter at a time.
DO NOT: store an ISFET probe in solution or use for long-term pH
measuring applications. Unlike BNC electrodes, stainless steel ISFET
electrodes should be stored dry. Extended immersion will shorten the life of
the probe.
DO NOT: leave an ISFET 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 environmentthat 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 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.

6
Display Features
1. Main Display. Displays pH, mV or Temperature.
2. pH Mode and pH Stabilization Indicator. pH is displayed when the meter is
measuring pH. This symbol will flash until a stable reading (endpoint) is
reached.
3. mV Mode Indicator.
4. Temperature Mode Indicator.
5. Calibration Mode Indicator.The CAL symbol is displayed when the meter
is in pH or temperature calibration mode.
6. ISFET Probe Indicator.PROBE is displayed when pH meter has detected the
presence of an ISFET probe. The PROBE icon is not displayed when the pH
meter is using a BNC electrode. FlashingPROBE icon indicates pending ISFET
probe failure.
7. One-Point Calibration Mode Indicator. 1PT is displayed when the meter is set for
making a one-point calibration.
8. Two-Point Calibration Mode Indicator.2PT is displayed when the meter is
set for making a two-point calibration.
9. Low Battery Indicator. BATT is displayed when approximately 10 hours of
battery life remain. Replace battery as soon as possible.

7
Keypad Functions
ON Turns the meter ON and OFF. When turned off, the
OFF meter retains the calibration in memory.
pH Selects 0.01 pH resolution, 0.1 pH resolution and mV
mV mode.
TEMP Selects Temperature mode. Repeatedly pressing TEMP
toggles between oC and oF.
CAL Selects the Calibration mode.
SELECT Scrolls through calibration buffer values.
BUFFER
↑↑ ↓↓ (CAL and SELECT BUFFER keys) Used to manually
set temperature compensation.
ENTER Used to confirm a displayed buffer value and begin
calibration. Used to set manual temperature compensation
value.

8
Connecting Electrodes
The meter is designed to use only one electrode at a time. The meter
automatically identifies whether a BNC or ISFET probe is attached when the
meter is first turned on. Always turn off the meter when changing electrodes.
CAUTION: Do not operate meter with both an
ISFET and a BNC probe attached.
1. ISFET pH Probe Connector.
The IQ150 Dual Technology pH meter accepts ISFET non-glass pH
electrodes. The temperature sensor is built-in to the ISFET probe so a
separate temperature probe is not required
2. Temperature Probe Connector for use with BNC Electrodes.
The temperature probe uses a 3.5 mm phono jack. When a temperature
probe is connected, the meter will Automatically Temperature
Compensate (ATC) pH values. Use only 30KÙ thermistors. Contact IQ
Scientific Instruments for temperature probes or pH electrodes with built-
in temperature sensors.
3. BNC Connector for Electrodes.
The IQ150 Dual Technology pH meter accepts any pH, ORP, or Ion
Selective Electrode with BNC connector. Be sure that both the
receptacle on the meter and the connector on the probe are clean and dry;
wet or dirty connections may cause unstable readings.

9
pH Calibration and Measurement
Range
The IQ150 can measure from pH 0 to 14. Temperature compensation is
automatic from 0 oC to + 100 oC. The meter can perform a one or two point
calibration using any buffer listed below.
Calibration Buffer Options
1.68, 4.01, 6.86, 7.00, 9.18, 10.01, and 12.45.
Caution: It is recommended that you avoid
temperatures above 60 oC (140 oF) when
possible. Elevated temperatures shorten the
life of pH probes.
Hints For Best Calibration Results
•Always begin each measuring session with a two-point calibration.
•Calibrate no greater than 3 pH units apart.
•If the ISFET probe is new or has not been in regular use, soaking the
probe in pH 7.00 buffer for at least 5 minutes is recommended.
•For best accuracy, when working at non-ambient temperatures, allow
the probe to equilibrate to the temperature of the buffer or sample
solution before starting calibration or pH measurement.
•Erroneous readings will occur if the meter is incorrectly calibrated; e.g.
setting the Buffer Value to pH 7.00 when the probe is in pH 4.00 buffer.
If unusual behavior occurs, turn the meter off, turn the meter back on,
recheck the buffer values, and recalibrate the meter.
•If calibration times are excessive (over 2 minutes) follow the cleaning
and reconditioning instructions in this manual.
•If you are calibrating with tris buffer, please contact IQ Scientific
Instruments for the best probe recommendation.

10
•Calibration with Two Buffers
Remember: Always use buffers that bracket the
sample pH range. (For example, if the sample is
about 8.5, use 7.00 and 10.01 buffers). The
narrowest calibration range gives the most
accurate reading.
1. Remove the protective cap from the probe tip and connect probe to the
meter. On new ISFET probes, a small amount of clear or blue gel may
be visible. If present, wipe the gel from the probe tip.
2. If using an ISFET probe that has not been in regular use, soak the
probe for at least five minutes in pH 7.00 buffer.
3. Place probe in first buffer solution. Stir briefly to dislodge any bubbles
from the probe surface.
4. Press ON/OFF to turn the meter on. If using an ISFET probe, be sure
PROBE icon is displayed.
5. If necessary, press pH/mV until pH is displayed.
6. Press CAL.
7. Meter will default to pH 7.00 buffer. If the display does not match the
pH of the buffer, press SELECT BUFFER until display matches first
buffer solution pH. The 1 PT icon will be displayed.
8. Press ENTER. The pH buffer value will begin flashing to indicate
calibration is underway. Wait until the large display stops flashing.
NOTE: When calibration is complete, the meter will display the
next buffer value for a two-point calibration.
9. Rinse probe in deionized water and place in second buffer. Stir briefly
to dislodge any bubbles from the sensor surface.
10. If necessary, press SELECT BUFFER until display matches second
buffer solution pH. The 2 PT icon will be displayed.
11. Press ENTER. The pH value will begin flashing to indicate calibration
is underway.Wait until the large display stops flashing.

11
12. When the pH buffer value stops flashing, two-point calibration is
complete. NOTE: When calibration is complete, the pH reading
displayed will be the automatically temperature compensated
(ATC) pH value of the buffer. For example, pH 7.00 buffer will be
corrected to 7.02 if the buffer is at 20 oC, pH 10.01 buffer will be
corrected to 10.06 at 20 oC.
13. Rinse probe in deionized water and place in sample. Read sample pH.
Remember: You can change resolution by pressing
the pH/mV key to optimize for accuracy or
response time. Use 0.01 pH resolution for
maximum accuracy. Use 0.1 pH resolution to
optimize for speed; the response time in 0.1
resolution will be approximately twice the speed of
0.01 resolution.
Calibration with One Buffer
Remember: One point calibration is recommended
only if the sample pH is very close to the
calibration buffer pH and an accuracy of ± 0.1 pH
is acceptable. It is highly recommended that each
pH measuring session begin with a two-point
calibration.
1. Follow steps 1 through 8 of the “Calibration with Two Buffers”
procedure.
2. Press the pH/mV key to exit calibration mode after the first calibration
point.
3. Rinse probe in deionized water and place in sample.
4. Change pH resolution by pressing the pH/mV key to optimize for
accuracy or response time.
How to Abort Calibration
If calibration times are excessive (pH value continues to flash for over 3
minutes) or you wish to stop during calibration for any other reason, press the
pH/mV key. The meter will enter the pH reading mode. Please refer to the
Troubleshooting Tips and the Cleaning and Reconditioning Instructions in
this manual if trouble is experienced in calibration.

12
Automatic Temperature Compensation
Automatic Temperature Compensation (ATC) only occurs when using an
ISFET pH probe (built-in temperature sensor) or when a BNC pH electrode is
used with the separate temperature plug attached. After calibration is
complete and the meter is in the pH mode, the pH values displayed will be
temperature compensated. If no temperature plug is attached when using a
BNC electrode, automatic temperature compensation is disabled and the
meter temperature display will default to 25oC.
The table below shows the pH values of buffers at various temperatures.
Nominal
Value
25 oC0oC5oC10 oC20 oC30 oC40 oC50 o C
1.68 1.67 1.67 1.67 1.67 1.68 1.69 1.71
4.01 4.00 4.00 4.00 4.00 4.01 4.03 4.06
6.86 6.98 6.95 6.92 6.87 6.85 6.84 6.83
7.00 7.12 7.09 7.06 7.01 6.99 6.97 6.97
9.18 9.46 9.40 9.33 9.23 9.14 9.07 9.02
10.01 10.32 10.25 10.18 10.06 9.97 9.89 9.83
12.45 13.42 13.21 13.00 12.63 12.29 12.04 11.70

13
Manual Temperature Compensation
Remember: ISFET probes have a built-in
temperature sensor and never require manual
temperature compensation.
Manual Temperature Compensation of BNC Electrodes
Procedure:
1. Connect the BNC jack to the meter. Be sure no temperature probe is
attached to the 3.5 mm phono receptacle.
2. Place probe in buffer.
3. Press ON/OFF to turn on the meter.
4. Press TEMP to enter temperature mode. Repeatedly pressing the TEMP
key toggles between oC and oF
5. Press CAL to enter manual temperature compensation mode.
6. Press ↑↑ (CAL key) or ↓↓ (SELECT BUFFER key) to manually set
temperature. The default temperature value is 25 oC.
7. Press ENTER to store temperature value.
8. Press pH/mV to exit manual temperature compensation mode.
9. Calibrate the pH meter following the directions in this manual. pH
values will compensate to the temperature set during the above
procedure.
Remember: Manual temperature compensation
will not take effect until a new pH calibration is
completed.

14
mV Measurement
Procedure:
1. Connect probe to meter.
2. Press ON/OFF to turn on meter.
3. Press mV to place meter in mV mode. The mV icon will be displayed.
The display shows the current mV reading.
Automatic Ranging of mV Display
From -199.9mV to +199.9mV will display 0.1 resolution. From 200mV to
1999mV meter will display 1 mV resolution.
Temperature Measurement
The meter will display temperature in Centigrade with a range of -5 oC to
+105 oC. The Fahrenheit display range is 20 oF to 200 oF.
Procedure:
1. Connect ISFET pH probe with built-in temperature sensor, or if using a
BNC electrode, connect a temperature probe to the 3.5 mm phono
receptacle.
2. Press ON/OFF to turn on meter.
3. Press TEMP to place meter in temperature mode. The display shows the
current temperature reading.
4. Pressing TEMP toggles between oC and oF. When displaying
temperature in Centigrade, the oCicon will be displayed.
Remember: Do not use a separate temperature
probe when using an ISFET probe with built-in
temperature sensor.
CAUTION: Do not expose the ISFET probe to
repeated temperature extremes (60 °C or higher).
Do not use the probe for applications that require
the probe to cycle between hot and room
temperature samples.

15
Cleaning and Reconditioning ISFET (non-glass) Probes
Cleaning with Detergent
Regularly clean the ISFET probe with detergent (a few drops of dish
detergent in a cup of warm water). Rinse well with deionized water.
ISFET probes can be cleaned with a toothbrush and detergent
Reconditioning with Warm Buffer
ISFET probes are designed to be stored dry and have a virtually unlimited
shelf life; however an extended period of dry storage can crystallize the KCl
gel at the reference junction. Heat pH 7.00 buffer to between 45 oC and 60 oC
(115 oF and 140 oF). Soak the probe for 2 minutes. Place the probe in room
temperature pH 7.00 buffer and allow to cool.
CAUTION: Do not use the probe as a
thermometer to determine if the buffer is above
60 oC. Sudden immersion in excessively hot water
may permanently damage the probe.

16
Cleaning With Alcohol or Methanol
The ISFET sensor (recessed shiny blue-green spot at the probe tip) can be
gently cleaned using alcohol or methanol and a wooden toothpick tipped with
a small amount of cotton wool. Be sure that the cotton tip is small enough to
actually make contact with the recessed sensor.
CAUTION: Cleaning with alcohol is not
recommended if the sample you are testing contains
proteins. Use Sodium Hypochlorite (see below).
CAUTION: Do not use metal objects such as
pins or paperclips to clean the sensor. The sensor
can be permanently damaged with aggressive
abrasion of the sensor surface.
Cleaning with Sodium Hypochlorite (Bleach)
If the ISFET probe has been exposed to fat or protein, the response time may
begin to slow. Soak the probe for five minutes in a 10:1 dilution of deionized
water to household bleach (0.5% solution of sodium hypochlorite). Brush
with a soft bristle brush or toothbrush to remove deposits. The sensor is
slightly recessed, be sure to make gentle contact with the sensor surface.
Rinse well with deionized water.
CAUTION: Do not soak the probe in sodium
hypochlorite for more than 5 minutes. Extended
immersion will permanently damage the probe.
Cleaning with Pepsin (Protein Deposit Removal)
Digest proteins by soaking for 15 minutes to one hour in Probe Cleaning
Solution, available from IQ Scientific Instruments as item #PCS50. Rinse
well with deionized water. Soak the probe for at least two hours in pH 4.00
buffer.

17
Cleaning and Reconditioning BNC (Glass Sensor) Electrodes
Check with the electrode product insert provided with your pH electrode for
full details on maintaining glass sensor pH electrodes.
Cleaning with Detergent
Vigorously stir the BNC probe in a solution of warm water and detergent (a
few drops of dish detergent in a cup of warm water) for 5 minutes. Rinse well
with deionized water.
Reconditioning with Warm Buffer
Many glass sensor problems are related to the reference junction. If using a
BNC pH electrode with a gel filled reference, the reference can be
reconditioned by soaking in 60 oC (140 oF) pH 4.00 buffer with added KCl for
ten minutes. Place the probe in room temperature electrode soak solution (pH
4.00 buffer with added KCl) and allow it to soak for 30 minutes.
Cleaning with Acid
Soak the BNC probe for 30 minutes in 0.1 molar HCl (about a 100:1 dilution
of distilled water to 37% hydrochloric acid). Rinse well, then soak in pH 4.00
buffer for 30 minutes.
CAUTION: When mixing acid, wear protective
clothing and eyewear. Always add acid to water--
NOT water to acid.
Cleaning with Methanol or Acetone (Grease and Oil Removal)
Rinse the BNC probe in methanol or acetone for 5 minutes. Rinse well with
deionized water. Soak the probe for at least two hours in pH 4.00 buffer.

18
Cleaning with Pepsin (Protein Deposit Removal)
Digest proteins by soaking for 15 minutes to one hour in Probe Cleaning
Solution, available from IQ Scientific Instruments as item #PCS50. Rinse
well with deionized water. Soak the probe for at least two hours in pH 4.00
buffer.
Etching with Ammonium Biflouride (DO NOT ETCH ISFET PROBES)
This is generally considered the method of last resort. If the BNC electrode
response is still sluggish after trying other cleaning methods, immerse
electrode tip in 0.1M NH4HF2(ammonium biflouride) for one minute. This
is a solution of about 5.7 grams ammonium biflouride to 1 liter of distilled
water. This will etch the surface of the glass and may restore performance.
Rinse well with deionized water. Soak the probe overnight in pH 4.00 buffer.
CAUTION: This solution is extremely hazardous.
Protective clothing and eyewear must be worn.
Dispose of used solution properly.
Titrations
Should you wish to use the IQ150 pH “Dual Technology” meter in a titration
application, please contact IQ Scientific Instruments for instructions.

19
Battery Replacement
A 9v alkaline battery powers the IQ150 meter. The expected battery life is
200 hours of operation. The BATT icon on the display indicates low battery
voltage. Replace the battery whenever low voltage is indicated.
To Replace the Battery:
1. Disconnect all connectors from the meter.
2. Remove the meter from the protective holster and turn the
meter upside down.
3. Gently open the battery compartment cover on the back of the
meter.
4. Remove the old battery, and install the new battery.
5. Replace the cover.
Automatic Shutoff
If the meter is on battery power and no key is pressed for 12 hours, the meter
will turn off automatically. Calibration is retained in memory after shutoff. If
the meter is operating on battery power and an error message is displayed for
20 minutes, the meter will turn off automatically. If the meter is operating on
AC power, it will not automatically turn off.
AC Power Adapter
The IQ150 pH meter can be used with an optional AC power adapter. Use
only IQ Scientific Instruments AC power adapters. The use of other adapters
may cause AC power interference that may result in unstable readings.
The meter automatically identifies the presence of the AC adapter and will not
use the internal 9-volt battery when the AC adapter is attached.