LaMotte DO 4000 Dissolved Oxygen Meter - Manual (Page 16)

TESTING
The DO 4000 has a constant polarization feature, which eliminates the
15 minute warm-up time between periodic use. If the meter has not
been set on this function, set constant polarization button to OUT
position on top of meter and wait 15 minutes before testing. For more
information on the constant polarization feature, see page 9. This
feature allows readings to be taken after the meter has been turned off
without waiting for the 15 minute warm-up time.
TEMPERATURE
1. Press “°C” button to turn the meter on.
2. Lower probe vertically at least 3.5" into sample. Swirl until display
stabilizes.
NOTE: It may take a minute or so for the display to stabilize (if
temperature is very low or very high).
3. Record reading as degrees Centigrade (°C).
4. Press “OFF” button.
DISSOLVED OXYGEN READING
1. Press “O
2
” button to turn the meter on.
2. Set the “SALINITY COMP” knob to the salinity of the sample
water.
3. Keeping probe at an angle, slowly lower at least 3.5" into sample.
Tap probe against side of beaker to remove air bubbles. Stir solution
gently with probe until display stabilizes. If testing deeper water,
gently raise and lower probe several times to remove air bubbles.
Continue to raise and lower to avoid oxygen starvation at the
membrane.
NOTE: It may take a minute or so for the display to stabilize. If
readings are erratic, see Troubleshooting on page 18.
4. Record reading as ppm Dissolved Oxygen.
5. Press “OFF” button and turn off constant polarization unless meter
is to be used again shortly.
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