Honeyman Automation Solutions P/L

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Humidity Probe

The HHP-420 humidity and temperature probe is a low-cost solution to a variety of humidity monitoring situations. It can be used to measure humidity from 0 to 100% RH and temperature from 0 to 100C, with an output of 4-20 mA.

Often the problem with humidity probes is not that the electronics fail, but rather that the sensor element becomes contaminated by the environment the sensor is measuring. The inherent variations in the manufacture of capacitive humidity sensors means a dirty sensor cannot be simply removed and a new element installed - the whole humidity probe must be replaced, which is a wasteful, costly and often difficult process.

The HHP-420 probe overcomes this problem by using a field-replaceable single chip relative humidity and temperature multi sensor module. The device includes a capacitive polymer sensing element for relative humidity and a bandgap temperature sensor. Each sensor is individually calibrated at the manufacturer in a precision humidity chamber. The final result is that when the sensor element becomes contaminated, the old sensor can be removed and a new one installed, requiring no recalibration of the sensor element. The final 4-20 mA analog output stage should not require readjustment. Additionally, because the humidity and temperature elements are incorporated in a common substrate, dewpoint measurements can be very accurate.

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