Combined air temperature and relative humidity sensor
The sensor FAR019xx combines in a single body the air temperature and the relative humidity transducers which makes it compact and cost saving.
The sensor body is made of anodized aluminium corrosion resistant. The protection shield is made of polycarbonate added with glassfiber, material with high resistance to ultraviolet radiation and atmospheric corrosion.
The two transducers are mounted on the top of a support made of plastic material due to minimize heat transfer from the base towards the measure elements.
The sensor body is inserted inside a natural ventilation shield (Fig. A) made of a pile of wedge - shaped plates drilled in the middle (so to have space for sensor housing) and air circulation is guaranteed by thermodynamic characteristics of the structure.
The three plates mounted on the top are not drilled in order to protect the transducer from direct and diffuse solar radiation, atmospheric agents as rain, hail and in general dust or dirt contamination.
The humidity sensor is made up of a transducer with hygroscopic polymers. The element is inserted on an electronic circuit giving a voltage signal output proportional to relative humidity.
Temperature measurement is done using a Pt100 transducer with a response curve according to the class 1/3 DIN - 43760 standard. Also in this case an electronic circuit will transform resistance variations in a voltage signal output proportional to the temperature.
At the bottom of the sensor body there is a waterproof connector for power supply and measurement signal. It’s a push pull self latching connector providing security against pull on the cable. Sensor installation doesn't require particular adjustments.
For the installation it's available a support to be fixed with a bracket to masts with external diameter of 50 or 60 mm.
For the calibration of the sensor, a certified instrument is used (reference ACCREDIA). The calibration based on comparison allows to maintain continuity with the metrological chain and assigns a scientific value to the measurement.
Forced ventilated radiation shield (option Fig. B):
The shelter is made by combining different aluminium cylindrical parts in order to obtain a cavity where it is possible to house the transducer. On the upper side it’s placed a convex plate to protect the probe from the rain or snow. In the lower part, a dedicated disk allows the blocking of the transducer inside the shield with forced ventilation. The shelter is made of white painted anodized aluminium, so as to maximize the reflection of solar radiation. A fan located under the top plate sucks air from the cavity in which the transducer is housed. The system is powered by 12Vdc and is able to generate an air flow of about 7m/s. The fact that the air is sucked prevents that the thermal energy generated by the fan can influence the transducer. In this way you can get to thermal equilibrium with the environment.