Vaisala HMP 35A, HMP35D Operating Instructions Manual
Operating instructions
Manuel d'utilisation
Bedienungsanleitung
Kaytt6ohje
HMP 35A & HMP 350
Sondes de mesure de
temperature et d'humidite
Humidity and
temperature probes
Mel"Ssonden fur Feuchte
und Temperatur
Kosteus- ja lamp6tila-
mittapaat
Doc. no. HMP35A-OO217-2.1
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SENSOR SYSTEMS
more often, depending on the conditions of use and
desired accuracy. A one-point calibration may be performed for the probes during actual measurement by
adjusting the trimmer potentiometer marked "DRY" in
the probe shaft. The field calibration can be performed
against a calibrated Vaisala humidity meter. For a high-
accuracy two-point calibration use a Vaisala HMK 11
calibrator and saturated salt solutions as described in
the HMK 11 Operating Manual. The calibration is first
done for the dry end and then for the wet end by
adjusting trimmer potentiometers marked "DRY" and
"WET". The potentiometers are located under a protective plug in the probe handle, see Figure 3. (Note: the
minimum output signal of 0.002 V corresponds to a
relative humidity of 0.2 %RH.)
Replacing the H-sensor
Detach the damaged sensor and replace it with a new
one. Handle the sensor with care. Calibrate the probe,
preferably using two-point calibration, before taking it
into use.
Chemical tolerances of the H-sensor
Long-term exposure of the sensor to certain chemicals
and gases may shorten sensor life and change its
properties. The following list give suggested maximum
ambient concentrations for some typical chemicals:
1. Organic solvents 1000...10000 ppm (typ.)
Aggressive chemicals
(e.g. strong acids such
as S02' H2SO4' H2S,
HCI, C12, etc.)
2
1...10 ppm (typ.)
100...1000 ppm (typ.)
10000...100000 ppm (typ.
3,
Weak
acids
Bases4.
Detailed information on allowed concentrations is
available on request from your Vaisala representative.
2
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