Instruction Manual
PD 300
5.2
Taking DO readings
During measurement, the probe can be:
z
Fully immersed in the solution
z
Partially immersed in the solution
Do not allow the probe’s membrane surface to touch
anything! The probe guard (the piece with holes fitted
over the end of the probe) protects the membrane; you
should leave this piece attached to the probe at all
times.
IMPORTANT:
Since the DO probe consumes oxygen
from the sample, the sample must constantly flow past
the membrane to achieve more accurate readings. You
can use a stirrer to accomplish this.
To take measurements:
1. Rinse the probe well with deionised rinse water or
rinse solution.
Figure 16: Change
measurement mode from %
saturation to mg/L
2. Select the appropriate measurement mode. Press the
MODE key to toggle between modes:
z
% Saturation
z
mg/L (ppm) **
z
pH
3. Dip the probe into the sample. Stir the probe gently to
homogenise the sample. Make sure that the sample is
continuously flowing past the membrane sensor.
4. Note the reading on the display. If the READY
indicator is switched on, it will appear when the
reading is stable.
Figure 17: Taking
measurement
5. Press the “LIGHT” key to activate the backlit LCD. This
helps you read measurements in dimly lit areas.
** To select between mg/L and ppm units, see Section 8.10.2 on page 46.
The ATC indicator should appear in the lower right hand corner of the display. If it does not,
this indicates an error.
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