4. Sources of errors
Humidity measurements are very sensitive to various influences:
- Temperature errors
Due to too short adjustment time, sunshine during the measurement, heating, cold outer wall, air
draft (e.g. fans), radiating hand and/or body heat etc.
-
Humidity errors
due to steam, water splashes, dripping water or condensation on the sensor etc.
Repeatability and long-term stability in operation are not impaired by this even if the probe has
been exposed to high humidity or saturation with water vapour over a lengthy period.
-
Contamination
of the humidity sensor can be largely avoided by using a corresponding filter. The filters must be
cleaned or replaced periodically depending upon the degree of contamination of the measuring
site.
Important!
The sensor is insensitive to chemicals, when they occur in normal concentrations (MAK values). At higher
concentrations or possibilities of contact with liquid chemicals, the manufacturer must always be
consulted!
5. Warranty
For verifiable material and manufacturing errors, the factory warranty is 12 months from the date of
delivery. Please refer to the "General conditions of sales and delivery" for details.
We accept no liability if this instrument is used in applications for which it is not intended.
6. Maintenance and service
6.1 Temperature
The probes are adjusted before delivery. A temperature readjustment is normally not required. When in
doubt about the correct calibration, please ask ROTRONIC AG.
6.2 Humidity
The probes are adjusted before delivery at 35 %, 80 % and 10 %RH. This results in optimum accuracy
over the full measuring range. To maintain this accuracy, we recommend you to subject the probe to a
check at least once a year. Please use only the ROTRONIC AG humidity standards for this!
These humidity standards consist of unsaturated salt solutions which can be kept indefinitely.
Important!
The ROTRONIC AG humidity standards (CH poisonous category 3) are normally not dangerous to
humans, but can irritate sensitive skin. In the case of contact with the skin or the eyes, the solution must
be washed out immediately and thoroughly with plenty of water. The ROTRONIC AG humidity standards
must not be consumed!
The calibration device for calibration and adjustment suitable for your type of probe and the required
humidity standards are obtainable as an accessory from ROTRONIC AG or one of our representatives.
Definitions:
Calibration = Control measurement with a ROTRONIC AG humidity standard
Adjustment = Calib additional readjustment of the probe to the set point value.
It is necessary to observe the following rules during calibration:
a) Calibrate in a room with constant temperature (if possible 23 °C ±2 °C) and avoid any thermal
influence which could influence the measurement: (air) draft, sunshine, heating, fans etc.!
b) Place the probe and especially its calibration device on an insulating surface (e.g. the lid of the
calibration set) so that there can be optimum temperature adjustment.
c)
Start with the calibration point of 35 %RH (potentiometer H35) and then adjust the points of 80 %RH
(potentiometer H80) and 10% RH (potentiometer Hmin) with a second and third calibration.
