Vaisala HPP272, User Manual, Page: 22 / 66

4. Installation
Accurate RH and RS measurement requires both humidity and temperature data from the
same environment. Install the H
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O
2
and humidity probe and the temperature probe in the
same measurement environment and temperature, approximately 6 ... 10 cm apart from each
other. Do not install the temperature probe directly above the H
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2
and humidity probe, as
moderate heat rising up from the H
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2
and humidity probe body may affect the ambient
temperature around the temperature probe.
When you choose the installation location for the probe, consider the following:
• Choose a location that represents the environment and process you want to measure.
Some factors may make a location unrepresentative of the process:
• Heat sources
• Materials that absorb H
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O
2
, such as several plastics, rubbers and sealing materials
• Limited air flow
• The probes withstand bio-decontamination process conditions. For signal cables, you
must verify their suitability in the installation environment.
• The probes withstand high air flow rates.
• For condensation monitoring with relative saturation, consider installing the probe close
to a surface where condensation may form (typically, on cooler surfaces in the bio-
decontaminated space).
• The probe is intended for use in atmospheric pressure. Do not install the probe in a
vacuum.
When there is H
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2
in the probe's environment, the probe must always be powered on. When
powered on, the PEROXCAP sensor is heated, which permits using the probe in condensing
H
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2
conditions, maintains measurement performance, and lengthens the probe's lifetime.
The filter is an essential part of the measurement. If the filter is
broken, dirty, or removed altogether, measurement does not work as intended.
• Do not touch the filter with bare hands. If you need to touch the filter, always
use clean gloves (rubber, cotton or similar material).
• Keep the filter free of any grease or oil.
• Do not touch any parts under the filter. Touching parts under the filter may
damage the sensors.
CAUTION!
HPP272 User Guide M211972EN-B
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