Vaisala HMP260 - Manual (Page 10)

HMP260 SERIES
Operating Manual
HMP260-U017en-1.5
4 1997-11-25
3. INSTALLATION
3.1. Selecting the place of installation
The transmitters should be installed in 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; it ensures that the sensor
head and the ambient air are at the same temperature.
Install the transmitter in a place where no cold or hot spot can develop. When
the sensor head is installed in a duct or a process 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. Installing the sensor head vertically is not
recommended. An uninsulated installation could lead to condensation in the
sensor head and even when no condensation occurs, the resultant air flow may
change the temperature near the sensor and distort the readings.
Install the sensor head in the process wherever possible; avoid sample flows
where the gas temperature can drop below dewpoint temperature. Install the
sensor head transversely against the direction of the process flow.
In duct or channel installations drill a hole ready for a reference meter. Plug
the reference hole tightly.
The transmitters are associated electrical apparatuses: the electronics housing
must be in the safe area and only the sensor head and its cable may go into the
hazardous area.
Install the electronics housing away from possible steams escaping from the
process.
NOTE
To ensure an IP 65 class protection:
1. Always mount the transmitter housing with the cable
bushings pointing downwards.
2. Make sure that the connection cable has the right
thickness ( ∅ 7...10 mm) and that the cable bushing
is carefully tightened.
3. Pay always special attention to closing the
transmitter cover carefully and remember to tighten
all four screws.