Vaisala HMD70 - Manual (Page 5)

HMD70U/Y Transmitters
U303en-1.1 Operating Manual
1997-07-31 1
1. PRODUCT DESCRIPTION
The HMD70 transmitters are duct mounted three-wire transmitters for the
measurement of humidity (HMD70U) and for the measurement of humidity
and temperature (HMD70Y).
The HMD70U/Y transmitters are easy to install and maintain: the electronics
can be disconnected without dismantling the installation. One point calibration
is easily performed with the HMI41 indicator and the calibration cable
19116ZZ.
Both transmitter types incorporate the HUMICAP
®
180 humidity sensor which
uses an operating principle based on changes in the capacitance of a thin
polymer film as it absorbs water molecules. The HMD70Y transmitters
measure temperature with the reliable Pt 1000 sensor.