Accumet AP84 User manual

OPERATING INSTRUCTIONS
accumet®13636AP84A
Portable Waterproof
pH/Dissolved Oxygen
Meter
Printed 1/02
IP
67

2
Table of Contents
1. Introduction............................................................................................4
2. Display and keypad functions .............................................................5-6
2.1 Display...................................................................................................................................5
2.2 Keypad...................................................................................................................................6
3. Preparation..........................................................................................7-9
3.1 Inserting the batteries..........................................................................................................7
3.2 Probe information — Connecting the probes...............................................................8-9
4. Calibration.......................................................................................10-19
4.1 Important information on meter calibration .................................................................10
4.2 Preparing the meter for pH calibration..........................................................................11
4.3 pH calibration................................................................................................................12-13
4.4 Preparing the meter for DO calibration..........................................................................14
4.5 Dissolved oxygen calibration in % saturation..........................................................15-16
4.6 Dissolved oxygen calibration in mg/l (ppm) mode ...............................................17-18
4.7 Temperature calibration....................................................................................................19
5. Measurement...................................................................................20-24
5.1 Taking DO readings......................................................................................................20-21
5.2 Taking pressure/salinity compensated DO measurements...................................21-22
5.3 Taking pH readings......................................................................................................23-24
5.4 Manual temperature compensation................................................................................25
6. Hold function........................................................................................26
7. Backlit LCD............................................................................................27
8. Advanced SETUP functions..............................................................28-55
8.1 Advanced setup mode overview................................................................................29-31
pH measurement mode overview ................................................................................29
% saturation measurement mode overview ...............................................................30
mg/l (ppm) measurement mode overview.................................................................31
8.2 pH mode—Program P1.0: Viewing previous calibration data....................................32
8.3 pH mode—Program P2.0: Viewing electrode data..................................................33-34
P2.1 Electrode offset.........................................................................................................33
P2.2 Electrode slope .........................................................................................................34
8.4 pH mode—Program P3.0: pH measurement configuration...................................35-37
P3.1 READY indicator and auto endpoint function....................................................35
P3.2 Selecting number of pH calibration points..........................................................36
P3.3 Selecting °C or °F .....................................................................................................37

3
8.5 pH mode—Program P4.0: Resetting to factory default settings.................................38
8.6 % saturation mode—Program P1.0: Dissolved oxygen parameters
Pressure adjustment mode..............................................................................................39
8.7 % saturation mode—Program P2.0: Offset adjustment................................................40
8.8 % saturation mode—Program P3.0: Previous calibration information......................41
8.9 % saturation mode—Program P4.0: Electrode properties ...........................................42
8.10 % saturation mode—Program P5.0: Unit configuration.......................................43-44
P5.1 READY indicator and auto endpoint function....................................................43
P5.2 Selecting °C or °F temperature readout................................................................44
8.11 % saturation mode—Program P6.0: Adjusting LCD brightness...............................45
8.12 % saturation mode—Program P7.0: Resetting to factory default.............................46
8.13 mg/l (ppm) mode—Program P1.0: Dissolved oxygen parameters....................47-48
P1.1 Pressure adjustment mode .....................................................................................47
P1.2 Salinity adjustment mode.......................................................................................48
8.14 mg/l (ppm) mode—Program P2.0: Previous calibration information.....................49
8.15 mg/l (ppm) mode—Program P3.0: Electrode properties ..........................................50
8.16 mg/l (ppm) mode—Program P4.0: Unit configuration........................................51-53
P4.1 READY indicator and auto endpoint function....................................................51
P4.2 Selecting mg/l or ppm units..................................................................................52
P4.3 Selecting °C or °F temperature readout................................................................53
8.17 mg/l (ppm) mode—Program P5.0: Adjusting LCD brightness................................54
8.18 mg/l (ppm) mode—Program P6.0: Resetting to factory default..............................55
9. Probe care and maintenance...........................................................56-59
9.1 pH electrode care ..........................................................................................................56-57
9.2 DO probe care.....................................................................................................................57
9.3 Membrane replacement ...............................................................................................58-59
10. Troubleshooting..................................................................................60
11. Error Messages....................................................................................61
12. Specifications......................................................................................62
13. Appendix 1: Meter theory ..................................................................63
14. Appendix 2: Pressure vs. Altitude table.............................................64
15. Appendix 3: Factory default settings.................................................65

4
1. Introduction
Thank you for selecting an accumet AP84 meter. This portable meter is a micro-
processor-based instrument that measures pH, dissolved oxygen and temperature.
It’s completely waterproof—and it floats! Your meter has many user-friendly
features, all of which are accessible through the membrane keypad.
Your meter includes batteries. Please read this manual thoroughly before operating
your meter.

5
2. Display and Keypad Functions
Display
The LCD has a primary and secondary display.
• The primary display shows the measured pH or dissolved oxygen reading.
• The secondary display shows the temperature of the reading.
The display also shows error messages, keypad functions and program functions.
2.1
Primary display
5.
6.
Secondary display
3.
2.
15.
16.
14.
12. 11.
8.
1.
13.
4.
10.
7.
1. SETUP mode indicator
2. MEASurement mode
indicator
3. CALibration mode
indicator
4. pH indicator
5. % saturation indicator
6. Salinity input indicator
7. Oxygen solubility
indicators
8. Temperature
indicators
9.Automatic Temperature
Compensation
indicator
10. ERRor indicator
11. Low battery indicator
12. Probe indicator
13. Calibration data
indicator
14. Function ON/OFF
indicator
15. HOLD indicator
16. READY indicator
9.

6
Keypad
The large membrane keypad makes the instrument easy to use. Each button, when
pressed, has a corresponding graphic indicator on the LCD.
ON/OFF............Powers and shuts off the meter.
HOLD ..............Freezes the measured reading. To activate, press HOLD while in
measurement mode. To release, press HOLD again.
NOTE: When auto endpoint feature is switched on, it automatically
holds reading after 5 seconds of stability. The HOLD indicator
appears on the display. Press HOLD to release.
MODE..............Selects the measurement parameter. Press MODE to toggle between
pH; DO % saturation; DO mg/l (ppm). In pH and DO mg/l (ppm)
calibration modes press MODE to access temperature calibration.
NOTE: To switch between mg/l and ppm modes, see page 52.
CAL/MEAS......Toggles user between Calibration and Measurement mode.
• If you were in pH mode, press CAL/MEAS to enter
pH calibration mode.
• If you were in DO % saturation mode, press CAL/MEAS to enter
DO % saturation calibration mode.
• If you were in DO mg/l (ppm) mode, press CAL/MEAS
to enter DO mg/l (ppm) calibration mode.
NOTE: Temperature calibration is available from both pH and DO
mg/l (ppm) calibration modes; see page 19 for directions.
In advanced set-up mode: Press CAL/MEAS to return to main menu
from sub menus. Press CAL/MEAS again to return to measurement
mode from main menu.
ENTER ............Press to confirm values in Calibration mode and to confirm
selections in SETUP mode.
▲▼..........Press in SETUP mode to
scroll through subgroups.
Also lets you increment/
decrement the values in
the mg/l and temperature
calibration modes.
SETUP..............Press to enter SETUP
mode. SETUP mode lets
you customize meter
preferences and defaults,
and view calibration and
probe data.
..........................LIGHT Press to activate
backlit display.
2.2

7
Battery
compartment
Remove these
two screws to
access battery
compartment
3. Preparation
Inserting the Batteries
Four AAA batteries are included with your meter.
1. Use a Phillips screwdriver to remove the two screws holding the battery cover.
See figure below.
2. Lift off battery cover to expose batteries.
3. Insert batteries. Follow the diagram inside the cover for correct polarity.
4. Replace the battery cover into its original position. Screw cover back into place.
3.1

8
Probe information
Your meter uses two probes:
• pH electrode with BNC connector
• dissolved oxygen/temperature probe with a notched 6-pin connector
The temperature sensing element built into the dissolved oxygen probe will also
compensate for pH readings as long as both probes are in your solution at the
same time.
You can use any standard pH electrode with a BNC connector with this meter.
If you do not have the DO probe connected you will need a separate temperature
probe to provide temperature compensation for pH readings (not included; contact
us for details). For the dissolved oxygen/temperature probe, you must use a dis-
solved oxygen/temperature probe with the notched 6-pin connector.
NOTE: Keep connectors dry and clean. Do not touch connectors with soiled hands.
3.2

9
To connect the pH electrode:
1. Slide the BNC connector of the probe over the BNC connector socket on the
meter. Make sure the slots of the connector are in line with the posts of the
socket. Rotate and push the connector clockwise until it locks.
See figure below.
2. To remove probe, push and rotate the connector counterclockwise. While
holding onto the metal part of the connector, pull probe away from the meter.
CAUTION: Do not pull on the probe cord or the probe wires might disconnect.
To connect the dissolved oxygen probe:
NOTE: Do not substitute other DO probes.
1. Line up the notch and 6 pins on the meter with the holes in the 6-pin connector.
Push down and turn the locking ring clockwise to lock into place.
See figure below.
2. To remove probe, turn the locking ring counterclockwise on the probe connector.
Pull probe away from the meter.
CAUTION: Do not pull on the probe cord or the probe wires might disconnect.
DO probe
(with 6-pin connector)
locking ring
pH Electrode
(with BNC connector)
top view of 6-pin
connector of
DO probe

10
For directions on how to calibrate your meter:
• See sections 4.2-4.3 on pages 11-13 for pH calibration
• See section 4.4-4.5 on page 14-16 for % saturation calibration
• See section 4.4 and 4.6 on page 14, 17-18 for mg/l (ppm) calibration
• See section 4.7 on pages 19 for Temperature Calibration
4. Calibration
Important Information on Meter Calibration
When you recalibrate your meter, old calibration points are replaced on a
“point by point” basis in pH and completely for % saturation and mg/l (ppm).
For example:
•pH: if you previously calibrated your meter at pH 4.01, 7.00, and 10.01, and you
recalibrate at pH 7.00, the meter retains the old calibration data at pH 4.01 and
pH 10.01.
•% saturation and mg/l (ppm): All new calibrations automatically override existing
calibration data.
To view current calibration points:
• pH: Program P1.0 in the SETUP section, page 32.
• % saturation: Program P3.0 in the SETUP section, page 41.
• mg/l (ppm): Program P2.0 in the SETUP section, page 49.
To completely recalibrate your meter, or when you use replacement probes,
it is best to clear old calibration data by resetting the meter.
To reset the meter to its factory defaults:
• pH: Program P4.0 in the SETUP section, page 38.
• % saturation: Program P7.0 in the SETUP section, page 46.
• mg/l (ppm): Program P6.0 in the SETUP section, page 55.
NOTE: Resetting the meter will set meter to factory defaults.
pH, % saturation and mg/l (ppm) must be reset separately.
4.1

11
Preparing the Meter for pH Calibration
Before starting pH calibration, make sure you are in the correct measurement mode.
When you switch on the meter, the meter starts up in the units last used. For
example, if you shut the meter off in "pH" units, the meter will read "pH" units
when you switch the meter on.
Do not reuse pH calibration solutions after calibration. Contaminants in the solution
can affect the calibration, and eventually the accuracy of the measurements. u
Be sure to remove the protective rubber cap from the pH electrode before
calibration or measurement. If the electrode has been stored dry, wet the probe in
tap water for 10 minutes before calibrating or taking readings to saturate the pH
electrode surface and minimize drift.
Wash your probe in deionized water after use, and store in electrode storage
solution. If storage solution is not available, use pH 4.0 or 7.0 buffer.
The pH/DO 300 meter is capable of up to 5-point pH calibration at pH 1.68, 4.01, 7.00,
10.01, and 12.45 to ensure accuracy across the entire pH range of the meter . The meter
automatically recognizes and calibrates to these standard buffer values, which makes
pH calibration faster and easier.
To calibrate at 5 points you must select a 5-pt calibration in SETUP mode program P3.2
on page 36. You can select 2, 3, 4 or 5 calibration points for pH calibration.
4.2

12
pH Calibration
1. If necessary, press the MODE key to
select pH mode. The pH indicator
appears in the upper right hand corner
of the display.
See figure
2. Rinse the pH electrode and DO probe
thoroughly with de-ionized water or a
rinse solution. Do not wipe the probe;
this causes a build-up of electrostatic
charge on the glass surface.
3. Dip both probes into the calibration
buffer. The end of both probes must be
completely immersed into the sample. Stir
the probe gently to create a homogeneous
sample.
4. Press CAL/MEAS to enter pH calibration
mode. The CAL indicator lights. The
primary display will show the measured
reading while the smaller secondary
display will indicate the pH standard
buffer solution.
See figure
5. Wait for the measured pH value to
stabilize.
See figure
pH
CAL
pH
READY
C
C
B
pH
CAL
pH
B
pH
ATC
MEAS
C
A
A
pH calibration
NOTE: We recommend that you perform at least a 2-point calibration using standard
buffers that bracket (one above and one below) the expected sample range.
You can perform a 1-point calibration, but make sure that the buffer value is
close to the sample value you are measuring.
The temperature sensing element is in the DO probe. For temperature
compensated readings and calibration, immerse the DO probe into the
calibration buffer while calibrating pH.
If the READY indicator has been activated
(set up program P3.1—see page 35), the READY
annunciator lights when the reading is stable.
4.3

13
6. Press ENTER to confirm calibration.
The meter is now calibrated to the
current buffer.
See figure
• If you are performing multipoint
calibration, go to step 7.
• If you are performing one-point
calibration, go to step 9.
7. Rinse the probe with de-ionized water
or a rinse solution, and place it in the
next pH buffer.
8. Follow steps 5 to 8 for additional
calibration points.
9. When calibration is complete,
press CAL/MEAS to return to pH
measurement mode.
Notes
To exit from pH Calibration mode without
confirming calibration, DO NOT press
ENTER in step 6. Press CAL/MEAS instead.
If the selected buffer value is not within
±1.0 pH from the measured pH value: the
electrode and buffer icon blink and the
ERR annunciator appears in the lower left
corner of the display.
To limit the number of pH buffer values
available during calibration, see section
P3.2 on page 36.
pH
CAL
pH
READY
D
D

14
Preparing the meter for DO calibration
Before calibrating your meter, make sure to rinse
the DO probe well with de-ionized water or rinse
solution.
NOTE: Do not let membrane surface of the DO
probe touch any other surface. The DO
probe guard (the piece with holes fitted
over the end of the probe) protects the
membrane; make sure this is always
attached to the probe while it is in use.
You can calibrate for dissolved oxygen in either
% saturation or mg/l (ppm). All new DO
calibrations automatically override existing
DO calibration data.
Before Dissolved Oxygen calibration
Before starting DO calibration, make sure you are in
the correct measurement mode. When you switch
on the meter, the meter starts up in the units last
used (either pH, mg/l, ppm, % saturation). For
example, if you shut the meter off in “mg/l” units,
the meter will read “mg/l” units when you switch
the meter on.
NOTE: Most users will calibrate to 100% saturation
even when working in mg/l. When calibrat-
ing the meter in mg/l mode, you can make
fine adjustments, typically to a midrange
value between 10 and 100%. If you are
calibrating to a midrange value, you need
to set the 100% saturation value first.
4.4
DO Probe guard

Dissolved Oxygen calibration in percent saturation
You can calibrate this meter quickly and easily in air. The exact calibration value
depends on barometric pressure. The meter is set to a factory default of 760 mm Hg,
which results in a calibration value of 100% saturation in air.
NOTE: If the barometric pressure setting has been changed from 760 mm Hg, the
calibration value in air will automatically adjust to a value other than 100%.
The adjusted value will be correct for the new barometric pressure setting.
• See page 39 to change the pressure setting.
• See Appendix 2 on page 64 for a chart of adjusted % saturation values.
15
To calibrate 100 % saturation:
1. Rinse the probe well with deionized
rinse water or rinse solution. For best
accuracy, wrap the end of the probe
in a damp cloth. Do not touch the
membrane.
2. Press the MODE key to select the
% saturation mode.
See figure
3. Press the CAL key. The CAL indicator
will appear above the primary display.
The primary display shows the current
value of the measurement and the
secondary display will show 100.0
(see NOTE above).
See figure
4. Hold the probe in the air (or in damp
cloth). Wait for the reading to stabilize.
If the Ready indicator feature is enabled,
it will appear when the reading is stable
(see page 43 for Ready indicator setup).
5. Press the ENTER key. The meter auto-
matically calibrates to 100.0% air satura-
tion and returns to Measurement mode.
See figure
4.5
A
A
B
C
B
C
Notes
The reading in the primary display in step 3 must read at 50% or above for the
calibration to work correctly. Whenever an error occurs during calibration, the
ERR indicator appears in the lower left hand corner of the display.
You can offset your % DO calibration: see page 40 for directions.

16
To calibrate 0 % saturation:
1. Rinse the probe well with deionized
rinse water or rinse solution. Do not
touch the membrane.
2. Press the MODE key to select the
% saturation mode.
See figure
2. Place the probe in zero oxygen
solution. Stir the probe gently to
homogenize the sample. Make sure
that the sample is continuously flowing
past the membrane sensor.
3. Press the CAL key. The CAL indicator
will appear above the primary display.
The primary display shows the current
value of the measurement and the
secondary display will show 0.0.
See figure
4. Wait for the reading to stabilize. If the
Ready indicator feature is enabled, it
will appear when the reading is stable
(see page 43 for Ready indicator setup).
5. Press the ENTER key. The meter auto-
matically calibrates to 0.0% saturation
and returns to Measurement mode.
See figure
Notes
The reading in the primary display in step
3 must read at 10% or under for the calibra-
tion to work correctly. Whenever an error
occurs during calibration, the ERR indicator
appears in the lower left hand corner of the
display.
You can offset your % DO calibration:
see page 40 for directions.
D
D
E
E
F
F

Dissolved Oxygen calibration in mg/l (ppm) mode
Calibrating the meter to 100 % in saturation mode will also calibrate the mg/l mode
at the value in mg/l corresponding to 100% saturation. This should produce
acceptable results in most applications.
This meter also lets you make a calibration adjustment in mg/l (ppm) mode
without affecting your % saturation calibration.
To select between mg/l and ppm units, see page 52.
17
To calibrate in mg/l (ppm) mode:
1. Calibrate 100% saturation per section 4.5
on page 15.
2. Rinse the probe well with deionized
rinse water or rinse solution. Wipe the
outside of the probe carefully (do not
touch the membrane).
3. Dip the probe into a sample of known
oxygen concentration. Wait for the
reading to stabilize. If the Ready
indicator feature is enabled, it will appear
when the reading is stable (see page 43
for Ready indicator setup).
NOTE: The sample must continuously flow
past the membrane for accurate
readings. A stirrer can keep the
solution agitated.
4. Press the MODE key to select the
mg/l (ppm) mode.
See figure
5. Press the CAL key. The CAL indicator
will appear above the primary display.
The primary display shows the current
value of the measurement and the sec-
ondary display shows the temperature.
See figure
6. Press the ▲and ▼keys to adjust
the reading.
7. Press the ENTER key. The meter
automatically calibrates to the
value you entered and returns
to Measurement mode.
See figure
4.6
A
A
B
C
C
B

18
Notes on mg/l (ppm) mode calibration
During mg/l (ppm) calibration, the meter adjusts to
the barometric pressure value that is programmed into
the meter. It also adjusts to the salinity value that is
programmed into the meter.
You can change the barometric pressure value and
salinity value in the mg/l (ppm) SETUP mode (see
pages 47-48 for directions).
Whenever an error occurs during calibration, the ERR
indicator appears in the lower left hand corner of the
display.

19
Temperature Calibration
The built-in temperature sensor included in the DO probe is factory calibrated.
Calibrate your sensor only if you suspect sensor drift that may have occurred
over a long period of time or if you have a replacement DO probe. Make sure DO
probe is attached before you perform the temperature calibration.
1. Switch the meter on. Press MODE to
select either pH or mg/l (ppm)
Measurement mode.
2. Press the CAL/MEAS key to enter
pH or mg/l (ppm) calibration mode.
The CAL indicator will appear above the
primary display.
See figure
3. While in pH or mg/l (ppm) calibration
mode, press the MODE key to enter
temperature calibration mode.
The primary display shows the last set
temperature reading and the secondary
display shows you the factory default
temperature value.
See figure
4. Compare the primary display reading
to a NIST-traceable thermometer or
another thermometer known to be
accurate.
5. Press the ▲or ▼keys to adjust
the primary display reading to agree
with your temperature standard.
See figure
6. Press the ENTER key to confirm
temperature calibration and return to
Measurement mode.
Notes
To exit from Temperature Calibration mode
without confirming calibration, DO NOT
press ENTER in step 6. Press CAL/MEAS
instead.
Temperature calibration is restricted to
±5°C from the factory default value
displayed during calibration (shown in the
secondary display).
A
B
C
4.7
A
B
C