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4 Maintenance
As the instrument does not have moving parts, i.e. is not subject to wear during operation, only
minimal servicing is required. Given that the sensor surfaces are normally kept clean by rain, it will
only be necessary to occasionally remove residues from the sensor surfaces in regions with very
little rain. Cleaning can be carried out as required using non-aggressive cleaning agents in water
and a soft cloth during routine checks.
Attention:
During storage, installation, de-installation, transport or
maintenance of the anemometer it must be ensured that no
water gets into the shaft and connector or cable gland of the
anemometer.
5 Calibration
The ultrasonic anemometer does not contain any adjustable components such as electrical or
mechanical trimming elements. All components and materials used show invariant behaviour in
terms of time. This means that no regular calibration is required due to ageing. Errors in measured
values are only caused by mechanical deformation of the transformer arms and associated
changes in measurement path lengths.
The acoustic-virtual temperature can be used to check the effective-acoustic measurement path
length. A change of 0.17% in the measurement path length and thus a measuring error of 0.17%
for the wind velocity corresponds to a deviation in the virtual temperature of 1 K at 20°C; there is a
measuring error of approx. 1% for the wind velocity with a 6 K deviation of acoustic-virtual
temperature.
In the event of any change in the measurement paths of the anemometer the manufacturer should
be consulted regarding recalibration.
Important:
Mechanical deformation of the measuring arms results in
errors in the measured values, which involve the output of
error telegrams / error signals to the analog interfaces.
6 Warranty
Damage caused by improper handling or external influences, e.g. lightning, do not fall under the
warranty provisions. The warranty entitlement expires if the instrument is opened.
Important:
The ultrasonic anemometer must be returned in the original
packaging as the warranty entitlement otherwise expires with
mechanical damage, e.g. deformation of measuring arms.