Vaisala HMP46 - Manual (Page 41)

HMI41 AND PROBES
M210316EN-A Operating Manual
37
9. MAINTENANCE
9.1 Changing the HUMICAP

180 humidity sensor
Unscrew the plastic grid (HMP41&45) or the sintered filter (HMP46).
Remove the damaged sensor and mount a new HUMICAP
® 180 humidity
sensor in its place. Handle the sensor with care. Calibrate the probe using a
two-point calibration procedure (see section 5.2.4).
9.2 Chemical tolerances of the HUMICAP

180 sensor
Long-term exposure of the HUMICAP

sensor to certain chemicals and gases
may affect the characteristics of the sensor and shorten its life. The following
table gives the recommended maximum ambient concentrations of some
chemicals:
ppm (typ.)
Organic solvents 1000...10 000
Aggressive chemicals (e.g. strong acids
such as SO
2
, H
2
SO
4
, H
2
S, HCl, Cl
2
, etc.)
1...10
Weak acids 100...1000
Bases 10 000...100 000
If necessary, request detailed information on allowed concentrations from
Vaisala representatives.
9.3 Using the HMP46 in high temperatures
The HMP46 probe can be temporarily used in high temperatures. For example,
the probe can be installed in +180 °C for 30 minutes provided that the probe
handle and 10 cm of the metal tube are at room temperature. When the
HMP46 probe is used in high temperatures, it warms up. Take necessary
precautions before touching it!