Accumet AP74 User manual

OPERATING INSTRUCTIONS
accumet®13636AP74A
Portable Waterproof
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..........................................................................................7-8
3.1 Inserting the batteries..........................................................................................................7
3.2 Connecting the probe...........................................................................................................8
4. Calibration.........................................................................................9-14
4.1 Preparing the meter for calibration...................................................................................9
4.2 Dissolved oxygen calibration in % saturation..........................................................10-11
4.3 Dissolved oxygen calibration in mg/l (ppm) mode ...............................................12-13
4.4 Temperature calibration....................................................................................................14
5. Measurement...................................................................................15-18
5.1 Taking DO readings......................................................................................................15-16
5.2 Taking pressure/salinity compensated DO measurements...................................17-18
6. Hold function........................................................................................19
7. Memory functions............................................................................20-21
7.1 Memory input.....................................................................................................................20
7.2 Memory recall.....................................................................................................................21
8. Advanced setup functions...............................................................23-39
Advanced setup mode overview......................................................................................23-25
mg/l (ppm) measurement mode overview...................................................................24
% saturation measurement mode overview .................................................................25
8.1 Program Clr: Memory clear..............................................................................................26
8.2 Program dPr: Dissolved oxygen parameters............................................................27-28
Pressure adjustment mode................................................................................................27
Salinity adjustment mode .................................................................................................28
8.3 Program OFS: Offset for % saturation measurement ...................................................29
8.4 Program CAL: Previous calibration information..........................................................30

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8.5 Program ELE: Electrode properties.................................................................................31
View probe slope................................................................................................................31
View % saturation offset....................................................................................................31
View 100% saturation mV value......................................................................................31
View 0% saturation mV value..........................................................................................31
8.6 Program COF: Unit configuration..............................................................................32-34
Ready indicator and auto endpoint function.................................................................32
Selecting mg/l or pm units...............................................................................................33
Selecting °C or °F temperature readout..........................................................................34
8.7 Program LCd: Adjusting LCD brightness......................................................................35
8.8 Program CLO: Setting the real-time clock ................................................................36-37
8.9 Program rST:Resetting to factory default settings .......................................................38
9. Probe care and maintenance...........................................................39-42
9.1 Probe care ............................................................................................................................39
9.2 Membrane replacement ...............................................................................................40-41
9.3 Electrolyte solution ............................................................................................................41
10. Troubleshooting..................................................................................42
11. Error Messages....................................................................................43
12. Specifications......................................................................................44
14. Appendix 1: Meter theory ..................................................................45
15, Appendix 2: Pressure vs. Altitude table.............................................46
16. Appendix 3: Factory default settings.................................................47

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1. Introduction
Thank you for selecting an accumet AP74 Dissolved Oxygen meter. This portable
meter is a microprocessor-based instrument that measures 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 a dissolved oxygen/temperature probe, electrolyte solution,
and batteries. Please read this manual thoroughly before operating your meter.

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2. Display and Keypad Functions
Display
The LCD has a primary and secondary display.
• The primary display shows the measured 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.
17.
18.
16.
10.
14. 13. 12.
8.
1.
15.
4.
11.
7.
1. SETup mode indicator
2. MEASurement mode
indicator
3. CALibration indicator
4. MEMory recall mode
indicator
5. % saturation indicator
6. Salinity input indicator
7. Oxygen solubility
indicators
8. Temperature
indicators
9.Automatic Temperature
Compensation
indicator
10. Clock indicator
11. ERRor indicator
12. MEMory location
indicator
13. Low battery indicator
14. Probe indicator
15. Calibration data
indicator
16. Function ON/OFF
indicator
17. HOLD indicator
18. READY indicator
9.

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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 auto endpoint feature.
MODE..............Selects the measurement parameter. Press MODE to toggle between
DO % saturation; DO mg/l (ppm); and date/time. In DO calibration
mode, press MODE to access temperature calibration.
NOTE: To switch between mg/l and ppm modes, see page 33.
CAL/MEAS......Toggles user between Calibration and Measurement 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 DO calibration
mode; see page 14 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.
..........................MI/MR work in the
measurement mode. MI
(memory input) stores the
measured value into memory.
MR (memory recall) recalls
the sets of values stored in
the memory.
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.
MI MR
2.2

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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

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Connecting the probe
Your meter includes a dissolved oxygen/temperature probe. The probe cable has a
notched 6-pin connector to attach the probe to the meter.
NOTE: Do not substitute other probes.
NOTE: Keep connector dry and clean. Do not touch connector with soiled hands.
To connect the probe:
1. Line up the notch and 6 pins on the top of the meter with the holes in the probe
connector. Push down and turn the locking ring to lock into place.
See figure below.
2. To remove probe, turn the locking ring on the probe connector.
Pull probe away from the meter.
CAUTION: Do not pull on the probe cord or the probe wires might disconnect.
3.2
locking ring
top view of 6-pin
connector

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4. Calibration
Probe guard
Preparing the meter for calibration
Before calibrating your meter, make sure to rinse the
probe well with de-ionized water or rinse solution.
NOTE: Do not let membrane surface of the probe
touch any other surface. The 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 calibrations
automatically override existing calibration data.
Before calibration
Before starting 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
mg/l, ppm, % air saturation, or clock). 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.
4.1