Manual Version 19 / 01-2019 II Page 33 of 44
SF2 ECCR OPERATION MANUAL
7.0 Calibrating the oxygen sensors
Calibrating the sensors is very important so that the correct oxygen partial pressure
of the breathing gas is displayed underwater. In principle, calibration is carried out
with pure oxygen and calibration is carried out at least every week or when external
circumstances change. If the air pressure changes (e.g. diving in a mountain lake or
in the event of large weather fluctuations), it should be recalibrated. Even if
maintenance has been carried out on the head, if water has got into the head or if
anything was noticeable during the last dive, it must be recalibrated.
There are several reasons for calibrating with pure oxygen. Since with rebreather
you usually dive with a set point of 1.0 - 1.3, the calibration with pure oxygen comes
closest to the gas mixture. In addition, an error when calibrating with air has greater
effects than with pure Oxygen. An error of around 1% with air calibration (e.g. 20%
instead of 20.9%) corresponds to a deviation of 5% in pure oxygen (95% instead of
100%). For this reason it is usually also on 98% and not on the actual
100% calibrated, as it must be assumed that the rinsing of the head is not complete
or that there is still residual moisture in the system or on the sensor membrane.
The calibration set is required to
calibrate the SF2. This consists
of a protective cardboard with
inflator nipple, an inflator hose
and the male coupling of the
Quick Disconnect Set. A
separate calibration gas is not
required, as the SF2's oxygen
cylinder can be used.
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