59
SECTION 5,
continued
3. Insert the probe into the sample to the desired depth. The
probe must be deep enough to cover the thermistor (metallic
button) located on the side of the probe.
4. Agitate the probe in the sample to dislodge air bubbles from
the sensing area of the probe tip.
5. Stir the sample vigorously with the probe or use a stir stand
and stir bar. When measuring deep bodies of water, create
sufficient flow across the probe tip by pulling on the cable to
move the probe up and down. When using a stir stand and
magnetic stir bar, increase the speed of the stir bar until the
displayed value no longer increases with the stirring rate.
6. When the reading on the meter stabilizes, record or store the
value in the meter memory.
7. Press the
DO %
key on the keypad to change the display from
concentration in mg/L to % saturation.
Note: The displayed % saturation will be based on a meter calculation for
the equilibrium dissolved oxygen concentration. The calculation
uses the sample temperature, salinity, barometric pressure, and
measured concentration in mg/L values. Changing the entry in
Setup 7 will alter the displayed mg/L or % saturation.
5.5.3
Probe Storage
To store the probe between measurements, insert the DO probe
tip into the calibration and storage chamber containing some
water or a wet sponge. Keep the probe connected to the meter,
if possible.
To prepare the probe for long-term storage (see Figure 8 on
page 51) complete the following steps:
1. Disconnect the probe from the meter.
2. Remove the batteries from the meter.
3. Remove the membrane cap assembly from the probe.
4. Rinse the anode, cathode, and membrane cap assembly
with water.
5. Shake the water out of the membrane cap.
