Digital window solar Thermo hygrometer
01378 Modern original models of a street thermometer with a transparent display. Mounted on the window from the outside anywhere. Large contrasting numbers. A system for monitoring trends in temperature and humidity.
In very wet tropical areas, humidity values may acquire a very low dynamic range, close to saturation conditions and, at the same time, to have a low temperature dynamic range and very low wind speed values. In certain periods of the year, these conditions may occur even in milder areas for short periods of time.
In such conditions, the hygrocapacitive element can get wet (from dew) and have no time to get dry and restore its measuring capacity. In this case, even if the humidity value decreases, the humidity measurement stabilizes to the saturation value or is – at any rate – underestimated.
Therefore two conditions may occur. So the first one refers to every category of “exchange type” humidity sensor; the second one is typical of capacity-measurement humidity sensors.
a) The layer of dew over the measuring element can reach 0,25 mm. Penman’s theory states that 8 hours are needed for the layer of dew to evaporate (30°C, 80 RH% with no air speed), or 4 hours (30°C, 60 RH% with no air speed). Moreover these time periods can be shorter in case of forced ventilation (not less than 1.5 m/s).
b) The manufacturers of hygro capacitive elements inform that a persistent humidity level on the element could produce a secondary absorption phenomenon, as well as cause a temporary shift of the humidity measurement equal to about +6%. In addition to this error disappears when the element is exposed for some hours to lower humidity values. Get 01378 now.