Thermo Fisher Scientific CyberScan DO 300 - Manual (Page 9)

Instruction Manual DO 300
6
4 CALIBRATION
4.1 Preparing the meter for calibration
The amount of oxygen dissolved in water will depend on its temperature, atmospheric
pressure and its salinity. While the pressure and salinity values are manually entered into the
instrument, the temperature is being measured by the probe. It is therefore very important that
the temperature is calibrated if necessary prior to the DO calibration.
The measurements of % Saturation of DO will linearly affect the measurement for DO in mg/L.
Hence calibration in % Saturation of DO should be carried out first.
Before calibrating your meter, make sure to rinse the probe well with DI (de-ionised) 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; make sure this is always attached to the
probe while it is in use.
You can calibrate for dissolved oxygen in either %
saturation or mg/L (ppm). When you recalibrate your
meter in % saturation mode, old calibrations in %
saturation will be replaced while the % saturation offset
adjustment will be erased. However, recalibration in the
mg/L (ppm) concentration mode will only replace the old
calibration in the mg/L (ppm) mode and do not affect the calibration in the % saturation mode.
Before Calibration
Before starting calibration, make sure you are in the correct measurement mode. When you
switch on the meter, the meter starts up in the mode last used (either in mg/L (ppm) or %
Saturation measurement mode or clock). For example, if you switch the meter off while it is in
the “mg/L” measurement mode, it will also be in the “mg/L” measurement mode when you
switch the meter on.
Figure 5: DO Probe guard