Vaisala HMP140 - Manual (Page 5)

HMP140A SERIES
U175en-1.5 Operating Manual
1999-12-08 1
1. PRODUCT DESCRIPTION
The HMP140A series transmitters are reliable and easy to use instruments for
the measurement of relative humidity and temperature. The series consists of
three different types of transmitters to be chosen according to the requirements
of the application:
•
HMP141A for wall installations
•
HMP142A for duct installations
•
HMP143A for installation in tight places
The configuration can be chosen from various possibilities to meet the specific
requirements of the customer. The transmitters can be ordered with a blank
cover or a cover with a local display which outputs relative humidity and
temperature readings. The reading to be displayed is chosen with a pushbutton
on the cover and the desired temperature unit (Celsius or Fahrenheit) can be
chosen with a jumper (see Appendix 2).
All HMP140A transmitters measure relative humidity in the range of
0...100 %RH and temperature from -40 to +60
°
C; the measurement is
temperature compensated. The HMP140A transmitters have four different
analogue outputs: 0...20 mA (4...20 mA), 0...1 V, 0...5 V and 0...10 V. The
outputs are also scalable if necessary, e.g. 4...20 mA from 0...20 mA.
The durable plastic cover provides IP65 protection from dust and sprayed
water. The HMP140A transmitters are therefore suitable for most indoor and
outdoor applications, including those with high humidities like indoor
swimming pools etc. These versatile transmitters are also easy to install and to
use. When necessary, they can be recalibrated on site with Vaisala’s HMI41
indicator equipped with an appropriate probe and optional calibration cable
(19116ZZ).
The HMP140A series transmitters incorporate the HUMICAP

180 sensor, the
operation of which is based on the changes in its capacitance as the thin
polymer film absorbs water molecules. The sensor is immune to most
chemicals and has an excellent long-term stability. The temperature is
measured with a Pt 1000 sensor.