Vaisala HMP140 - Manual (Page 7)

HMP140A SERIES
U175en-1.5 Operating Manual
1999-12-08 3
3. INSTALLATION
3.1 Selecting the place of installation
Select a place that gives a true picture of the environment or process and is as
clean as possible. Air should circulate freely around the sensor. A rapid air
flow is recommended as it ensures the same temperature for the ambient air
and the sensor head.
Install the transmitter in a place where no cold or hot spot can develop. If the
sensor head is installed in a duct or channel where the temperature is different
from the ambient temperature, insulate the point of entry; this is particularly
important if the transmitter is installed with the sensor head pointing
downwards. Vertical installation of the HMP142A and HMP143A is not
recommended; they should be mounted with the sensor head horizontally
whenever possible. An uninsulated installation might lead to condensation on
the sensor head and even if no condensation occurs, the resultant air flow may
change the temperature near the sensor head and distort the readings.
3.2 Mounting
The electronics of the HMP140A series can be disconnected for ease of
installation and service. The housing can be conveniently installed and the
electronics then consequently mounted. For service and maintenance purposes
the electronics can be disconnected without disconnecting the cabling, and
taken to an appropriate environment for necessary adjustments.
6.5
4.2
60
83
.5
60
Figure 3 Drilling dimensions (in mm)