User`s guide

DO700 V1.0 8/09
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Dissolved Oxygen Water Sample Test
• To measure moving water (water sample velocity of flow >5cm/s) insert the DO
electrode into the water. The water surface should cover the electrode’s thermistor
(temperature sensor). The recommended electrode orientation with regard to the water
is a 45°to 75°angle. Move the electrode around in the water and allow 3 to 5 minutes to
take the reading.
• To measure in static water: Insert the DO electrode into water, water surface should
cover the location of the electrode’s thermistor (temperature sensor), the direction for
the electrode with respect to the water is a 45°to 75°angle. Quickly stir the electrode in
water at a speed >5cm/s. Allow 3 to 5 minutes while taking the reading.
• To test in slower flowing water: Use the first method above but stir the electrode faster
in the water.
Dissolved Oxygen Measurement and Calibration Considerations
• The air temperature and water temperature should be within 10 degrees C, if the
temperature difference is greater, please immerse the electrode in the sample water for
10 minutes and then calibrate.
• After each start-up, the electrode must be polarized and a calibration must be
performed; do not turn the meter OFF (when in the DO mode, the default auto power
off time is zero).
• During DO tests, the temperature affects the measurement greatly. The electrode’s
thermistor should come in direct contact with the water sample. Please allow 3 to 5
minutes for the thermistor to gage a stable temperature measurement.
• DO measurements are also greatly affected by Barometric pressure. The DO700 meter
has an automatic Barometric pressure compensation function.
• The DO electrode must not be left static in the test solution. Always stir the electrode in
the solution.
• When measuring, remove air bubbles from the solution under test otherwise
measurement accuracy will be compromised.
• Small air bubbles in the electrode’s electrolyte are acceptable; however larger bubbles
must be removed.
• Keep the surface of the DO electrode moist to protect the cathode electrolyte. The
supplied storage sponge should always be kept moistened for proper storage.
• The salinity electrode is installed in the DO electrode. Its surface is plated with a layer
of platinum (black) to reduce electrode polarization. This surface must not be rubbed or
wiped (clean by swirling it in water). Wash organic matter off of the surface with
lukewarm water containing detergent or use alcohol if necessary.
• For any display abnormalities while measuring or calibrating, set the meter to its factory
default settings using parameter P7 (explained in next section). If abnormalities persist,
the electrode most probably needs replacing.