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Summary of Contents for Accumet AP74
- Page 2 OPERATING INSTRUCTIONS accumet ® 13636AP74A Portable Waterproof Dissolved Oxygen Meter Printed 1/02...
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Page 3: Table Of Contents
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. - Page 4 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...
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Page 5: Introduction
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. -
Page 6: Display And Keypad Functions
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. Primary display 14. -
Page 7: Keypad
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. -
Page 8: Preparation
3. Preparation Inserting the Batteries Four AAA batteries are included with your meter. Use a Phillips screwdriver to remove the two screws holding the battery cover. See figure below. Lift off battery cover to expose batteries. Insert batteries. Follow the diagram inside the cover for correct polarity. Replace the battery cover into its original position. -
Page 9: Connecting The Probe
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: Line up the notch and 6 pins on the top of the meter with the holes in the probe connector. -
Page 10: Calibration
4. Calibration 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;... -
Page 11: Dissolved Oxygen Calibration In % Saturation
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%. - Page 12 To calibrate 0 % saturation: Rinse the probe well with deionized rinse water or rinse solution. Do not touch the membrane. Press the MODE key to select the % saturation mode. See figure Place the probe in zero oxygen solution. Stir the probe gently to homogenize the sample.
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Page 13: Dissolved Oxygen Calibration In Mg/L (Ppm) Mode
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. - Page 14 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 pro- grammed into the meter. You can change the barometric pressure value and salinity value in the mg/l (ppm) Set Up mode (see pages 27-28 for directions).
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Page 15: Temperature Calibration
Temperature Calibration The built-in temperature sensor included in the 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 probe. Switch the meter on. Press MODE to select mg/l (ppm) Measurement mode. -
Page 16: Measurement
5. Measurement Taking DO readings During measurement, the probe can be: • fully immersed in the solution • partially immersed in the solution Do not allow the probe’s membrane surface to touch any- thing! The probe guard (the piece with holes fitted over the end of the probe) protects the membrane;... - Page 17 Taking measurements with READY indicator selected on If the READY indicator has been activated, the READY annunciator lights when the reading is stable. Switch the READY indicator on or off in the Set up program— see page 32 for directions. Taking measurements with the auto endpoint feature selected on When a reading is stable for more than 5 seconds, the auto endpoint feature will automatically “hold”...
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Page 18: Taking Pressure/Salinity Compensated Do Measurements
Taking pressure/salinity compensated DO measurements If necessary, you can adjust the pressure and salinity values of your measurements in the Set Up mode. The DO meter will automatically compensate for salinity and pressure based on the values entered in the setup functions. The meter is factory set at 760 mm Hg (101.3 Pascals) pressure adjustment and a factor of 0.0 salinity adjust- ment. - Page 19 Salinity adjustment NOTE: this mode appears in ppm (mg/l) measurement mode only. Press the Mode key to select mg/l (ppm) mode. Press the SETUP key to enter Set Up mode. key until the upper display Press the shows “dPr”. See figure Press the ENTER key until the upper display shows a number and the lower display shows “SAL”.
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Page 20: Hold Function
6. HOLD function This feature lets you freeze the dissolved oxygen and temperature readings for a delayed observation. HOLD can be used any time when in MEAS mode. To hold a measurement, press the HOLD key while in measurement mode. "HOLD" will appear on the display. -
Page 21: Memory Functions
7. Memory functions Memory Input Your meter stores data in sets that include: • dissolved oxygen with corresponding temperature reading • time and date reading was taken You can store up to 50 sets of data in any combination of %, mg/l, or ppm readings. To store a reading: During any measurement function (MEAS), press the MI key to input any... -
Page 22: Memory Recall
Memory Recall This function recalls the previous readings stored in the memory. You can only access MR from the MEASurement mode. Memory recall is in “Last In First Out” order. To recall readings: Press the MR key once to retrieve the last reading stored. -
Page 24: Advanced Setup Functions
8. Advanced set up functions The advanced set up mode lets you customize your meter’s preferences and defaults. Your AP74 waterproof meter features different sub groups that organize all set-up parameters. This meter blanks out subgroups that do not apply to the measurement mode [% saturation or mg/l (ppm)] you are in when you enter Setup mode. -
Page 25: Mg/L (Ppm) Measurement Mode Overview
Advanced set-up mode detailed overview Press the SETUP key to enter Set up mode. Press the keys to scroll through sub groups. mg/l (ppm) measurement mode CLr: Memory clear • Clear all stored readings Instructions on page 26 dPr: Dissolved oxygen parameters •... -
Page 26: Saturation Measurement Mode Overview
% saturation measurement mode CLr: Memory clear • Clear all stored readings Instructions on page 26 dPr: Dissolved oxygen parameters • Select Hg or Pa barometric pressure units • Select barometric pressure Instructions on pages 27-28 OFS: % saturation offset adjustment •... -
Page 27: Program Clr: Memory Clear
Clr: Memory Clear Use this sub group to clear all memory values when you need to store a new series of values. This lets you avoid confusing the old values with the new ones. NO is the default setting. NOTE: Selecting YES will wipe out all memory. From measurement mode: Press the Set up key to enter Set Up mode. -
Page 28: Program Dpr: Dissolved Oxygen Parameters
dPr: Dissolved Oxygen Parameters This sub group lets you adjust the barometric pressure and salinity. Pressure adjustment mode Barometric pressure is vital to correct dissolved oxygen measurements. You need to enter the correct barometric pressure of the area you are measuring. This mode lets you perform two functions: •... -
Page 29: Salinity Adjustment Mode
Salinity adjustment mode NOTE: this mode appears in mg/l (ppm) measurement mode only. Salinity correction mode lets you correct for the variations in oxygen solubility due to salt concentration in the sample. From measurement mode: Press the Mode key to select mg/l (ppm) mode. -
Page 30: Program Ofs: Offset For % Saturation Measurement
OFS: Offset for % saturation measurement NOTE: this sub group appears in % saturation measurement mode only. Use the offset adjustment to act as an offset at values between 0 and 100%. It is useful to match against end-user standards (i.e. a test kit value). From measurement mode: Press the Mode key to select % saturation mode. -
Page 31: Program Cal: Previous Calibration Information
CAL: Previous calibration information This sub group shows you the previous calibration data, along with date and time of calibration. This is a “view only” parameter. In % saturation mode: calibration information is shown in % saturation units. In mg/l (ppm) mode: calibration information is shown in mg/l (ppm) units. From measurement mode: Press the Mode key to select the calibration data you want to view:... -
Page 32: Program Ele: Electrode Properties
ELE: Electrode properties These “view only” parameters show the electrode properties for diagnostic purposes: A. probe slope: lets you view the calibration slope of the probe. This mode displays slope from 0.5 to 1.999 % of slope (1.0 = 100%). B. -
Page 33: Program Cof: Unit Configuration
COF: Unit configuration Unit configuration mode lets you select the following parameters: A. Ready indicator and auto endpoint function B. mg/l or ppm units (available from mg/l or ppm mode only) C. Temperature in °C or °F READY indicator and auto endpoint function The first program lets you select: •... -
Page 34: Selecting Mg/L Or Pm Units
Selecting mg/l or ppm units NOTE: this mode appears in mg/l (ppm) measurement mode only. This mode lets you select between mg/l or ppm dissolved oxygen units. From measurement mode Press the Mode key to select mg/l (ppm) mode. Press Setup key to enter Set Up mode. Press the keys to scroll through subgroups until you view parameter... -
Page 35: Selecting °C Or °F Temperature Readout
Selecting °C or °F temperature readout This meter lets you select between °C and °F units for temperature readings. From measurement mode Press Setup key to enter Set Up mode. Press the keys to scroll through subgroups until you view parameter “COF”... -
Page 36: Program Lcd: Adjusting Lcd Brightness
LCd: Adjusting LCD brightness This mode lets you adjust the brightness of the backlit LCD. Selecting a dimmer backlighting level helps conserve batteries. From measurement mode Press Setup key to enter Set Up mode. Press the keys to scroll through subgroups until you view parameter “LCd”... -
Page 37: Program Clo: Setting The Real-Time Clock
CLO: Setting the real-time clock Your meter features a real-time calendar and clock. This helps you meet GLP (Good Laboratory Practice) standards. From measurement mode Press Setup key to enter Set Up mode. Press the keys to scroll through subgroups until you view parameter “CLO”... - Page 38 Press the ENTER key to confirm the date and move to “hour” selection. The “hour” digits will flash. See figure Press the keys to toggle to the correct hour. Note the “AM” and “PM” indicator on the lower portion of the display. Press the ENTER key to confirm the hour and move to “minute”...
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Page 39: Program Rst: Resetting To Factory Default Settings
P6.0: Resetting to factory default settings This program lets you reset all parameters to factory default settings. This clears all calibration data, memory, and any other setup functions you might have changed. However, the following settings will remain as you have set them: •... -
Page 40: Probe Care And Maintenance
9. Probe care and maintenance Probe care The probe is a galvanic measuring element which produces an output proportional to the oxygen present in the medium in which it is placed. The galvanic probe design lets you take measure- ments immediately—without the typical 15 minute wait of other dissolved oxygen probes. -
Page 41: Membrane Replacement
Membrane replacement Replacement of the membrane is required only when you cannot calibrate the probe, or if the membrane is damaged. Typical membrane damages are punctures or wrinkles caused during measurements or cleaning. To replace the probe membrane: Pull off the probe guard. Unscrew the membrane cap from the probe. -
Page 42: Electrolyte Solution
Using the installation tool, unscrew and remove the membrane lock from the Installation tool membrane cap. See figure Remove the membrane and O-ring. Insert notches Discard both. on installation tool into slots on Rinse the membrane cap and membrane lock membrane lock. -
Page 43: Troubleshooting
10. Troubleshooting Problem Cause Solution Power on but a) Batteries not in place. a) Check that batteries are in no display place and making good contact. b) Batteries not in correct b) Reinsert batteries with polarity (+ and –). correct polarity. c) Weak batteries. -
Page 44: Error Messages
11. Error Messages Indicates Cause Solution Display Unrecognized input Wrong input in Release key. Select annunciator from keypad selected mode. valid operations depending on mode. CAL & Err Calibration error Wrong value input Check your input value, annunciators at calibration. clean probe. -
Page 45: Specifications
12. Specifications Mode mg/l (ppm) % saturation Temperature 0.0 to 50.0˚C / Range 0.00 to 19.99 mg/l (ppm) 0.0 to 199.9% 32.0 to 122.0°F Resolution 0.01 mg/l (ppm) 0.1% 0.1˚C or °F Accuracy ±1.5% of full scale ±1.5% of full scale ±0.3˚C / ±0.6 °F Temperature compensation: automatic from 0 to 50°C Salinity correction:... -
Page 46: Appendix 1: Meter Theory
14. Appendix 1: Meter Theory Dissolved oxygen levels in natural and waste waters depend on the physical, chemical, and biochemical activities in the water body. This meter uses a galvanic probe. It consists of a cell that contains electrolyte and that is enclosed by a selective membrane, and two metallic electrodes. -
Page 47: 15, Appendix 2: Pressure Vs. Altitude Table
15. Appendix 2: Pressure vs. Altitude table Barometric pressure affects DO readings, therefore this meter lets you enter the cor- rect barometric pressure at your altitude. If you do not have equipment that lets you measure the exact barometric pressure at your altitude, you can estimate it using the chart below. -
Page 48: Appendix 3: Factory Default Settings
16. Appendix 3: Factory Default Settings Resetting the meter to factory default settings clears all calibration data and memory, and returns other setup functions to the default settings shown in the table below. However, the following settings will remain as you have set them: •...
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