Vaisala AWS310-SITE, Integration Manual

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3.4 Vaisala HUMICAP Humidity and
Temperature Probe HMP155
Figure 3 Vaisala HUMICAP Humidity and
Temperature Probe HMP155 with additional
T
‑
Probe
HMP155 measures relative humidity and air temperature. Humidity measurement on the
sensor is based on the capacitive thin film polymer HUMICAP sensor. Temperature
measurement is based on resistive platinum (Pt100) sensors. Both the humidity and
temperature sensors are located at the tip of the probe, protected by a removable filter.
The weather station uses the relative humidity and air temperature measurements for
calculating the dew point temperature.
HMP155 is installed inside a radiation shield, which ensures proper ventilation while
protecting the sensor from solar radiation and precipitation. The shield provides ventilation
while blocking both direct and reflected solar radiation.
HMP155 housing has an IP66 classification. To counter condensation forming on the sensor
in humid conditions, HMP155 can be equipped with an optional sensor tip warmer. When the
warmed option is used, the additional T
‑
(temperature) probe measures air temperature and
the system calculates relative humidity.
More information
‣ RWCC components for AWS310-SITE (page 12)
‣
Installing HMP155 (page 24)
Chapter 3 – Sensors
21