Instructions

6 | Bases for measurement DO-400
16 / 29 B-H86.0.21.DB214-1.0
ter; the value is 0. A salinity of approx. 35 PSU is normal for sea water. The salinity
correction is adjusted to aqueous media having a chemical composition corresponding
to sea water. The International Oceanographic Tables (IOT) are used as a basis for
the correction.
6.2.2 Environmental pressure, water depth and air pressure
The environmental pressure, water depth and air pressure play an important role at
the place of measurement for the following points:
– Calculation of oxygen saturation in % SAT. Clean water can achieve 100 % satura-
tion in air. There must be no oxygen-depleting processes, such as biological de-
caying processes, chemical effects or oxygen enhancing processes, such as ex-
cessive ventilation or photosynthesis. This could result in an oversaturation above
100%.
– Calculation of the oxygen concentration in mg/l
– The valuation of calibration
Adjusting the pressure parameter on the product is recommended prior to calibration.
In the scope of measuring accuracy, specifying the current air pressure in the region
based on meteorological data or the standard pressure based on sea level is suffi-
cient.
For example:
0 m above NN: 1013 hPa
300 m above NN: 978 hPa
600 m above NN: 943 hPa
1000m above NN: 899 hPa
6.3 Commissioning, filling and maintenance of the
sensor
Description
The sensor is delivered dry. Therefore, the sensor is well-suited for storage. The
sensor must be filled in good time before the measurement. A wait time of approx. 2
hours after filling should be planned in order to allow the sensor to stabilise. Commis-
sioning with initial filling, filling and maintenance of the sensor are explained in the fol-
lowing chapter.
Prerequisite
– Protective goggles
– Protective gloves
– A suitable screwdriver
– Pipette
– Household towel
– KOH electrolyte
– A spare GWOK 02 membrane head, if applicable
Instruction
1. Unscrew the membrane head.
2. Unscrew the seal screw from the refill opening.
NOTE
If the sensor was already filled and deposits have formed, it should be cleaned with
KOH via the fill opening or removed. Loose residue can be rinsed out in the process.
The platinum cup on the front of the membrane must be clean. Remove any soiling or
electrolyte solution with a paper towel.