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Maintenance, 1 changing the humicap(180 humidity sensor, 2 chemical tolerances of the humicap(180 sensor – Vaisala HMP46 User Manual

Page 41: 3 using the hmp46 in high temperatures, Changing the humicap, 180 humidity sensor, Chemical tolerances of the humicap, 180 sensor, Using the hmp46 in high temperatures

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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!

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