AFS-G1
AFS-G1 K04/1019
page 7
8. Operation
Attention! With restrictions in the upper range of operation, the
possible tolerances (measurement accuracy, switching difference
and temperature coefficient) should be observed when adjusting the
switch point.
8.1. Calibration
The Hygrostats are factory set at a room temperature of 23 °C and 50% relative
humidity, relative to the average air pressure of 430m NN.
If however, subsequent adjustment should be necessary, the following procedure
should be observed:
Ensure that the ambient humidity and the ambient temperature are constant.
If possible, use a psychrometer for checking (do not use equipment with
capacitive sensors).
Leave the equipment to be checked for at least
1 hour in
a
constant checking
climate.
The adjuster screw is at the end of the sensor - fixed with screw securing
lacquer. After removing the lacquer, the adjuster screw can be moved. A right-
hand rotation means that the measured value goes down, and with a left-hand
rotation the measured value goes up. After calibration, the adjuster screw
should again be secured.
Attention! Moving the adjuster screw nullifies the guarantee.
Important:
The water absorption capacity of the air is influenced, amongst other
things, by the temperature. This is a physical law (which can be seen from the hx
diagram of Mollier). The higher the air temperature, the greater the volume of
water vapour that can absorbed up to saturation point (100 % RH). If a Hygrostat
is calibrated at a fluctuating air temperature, there will be an irregular, non-
homogeneous measured medium, resulting in calibration errors. The table below
shows the influence of the air temperature on air humidity. If, for example,
calibration occurs at an air temperature of 20 °C and 50 % RH, and at a
temperature fluctuation of just ±1 °K, then there will be a humidity fluctuation in
the measured medium (air) of ±3.2 % RH.
10 °C
20 °C
30 °C
50 °C
10 % RH
+/- 0,7 % RH
+/- 0,6 % RH
+/- 0,6 % RH
+/- 0,5 % RH
50 % RH
+/- 3,5 % RH
+/- 3,2 % RH
+/- 3,0 % RH
+/- 2,6 % RH
90 % RH
+/- 6,3 % RH
+/- 5,7 % RH
+/- 5,4 % RH
+/- 4,6 % RH
9.
