The Vaisala Meteorological Installation Kit HMT330MIK enables the Vaisala HUMICAP® Humidity and Temperature Transmitter HMT337 to be installed outdoors to obtain reliable measurements for meteorological purposes.
True Humidity Readings in Condensing Conditions
In weather observations dew formation makes reliable humidity measurement difficult. When dew has formed on the humidity sensor, it is impossible to obtain a true reading until this dew evaporates. Both the PTU307 and HMT337 avoid this problem by warming the probe. When warmed, the relative humidity inside the probe stays below the ambient level. With an accurate temperature measurement, the ambient dewpoint can be calculated precisely. To obtain the ambient relative humidity, an additional probe measures the ambient temperature, and the transmitter calculates the relative humidity from the dewpoint and temperature values.
Open Shield Prevents Microclimates
The warmed probe of the HMT337/ PTU307 is mounted in a shield which is open at the bottom to ensure steady air circulation to the sensor even in calm weather.
In traditional radiation shields sleet or snow can accumulate on the shield and prevent the proper air circulation through the shield, and create a humid microclimate until the snow melts.
Essential for Critical Weather Measurements
Obtaining a true humidity reading is particularly important e.g. in traffic safety: at airports and at sea as well as on the roads. It is essential, for example, in fog and frost prediction.