ROTRONIC HF3 - Manual (Page 10)

E-M-HF3-V1_22
Rotronic AG
Bassersdorf, Switzerland
Document code Unit
HygroFlex HF3 Transmitters and Thermo-
hygrostats: User Guide Instruction Manual
Document Type
Page 10 of 27
Document title
© 2009-2011; Rotronic AG E-M-HF3-V1_22
5 Mechanical installation
5.1 General guidelines
Relative humidity is extremely dependent on temperature. Proper measurement of relative humidity requires
that the probe and its sensors be at exactly the temperature of the environment to be measured. Because of
this, the location where you choose to install the probe can have a significant effect on the performance of the
instrument. The following guidelines should guarantee good instrument performance:
a) Select a representative location: install the probe where humidity, temperature and pressure
conditions are representative of the environment to be measured.
b) Provide good air movement at the probe: air velocity of at least 200 ft/ minute (1 meter/second)
facilitates adaptation of the probe to changing temperature.
c) Avoid the following: (1) Close proximity of the probe to a heating element, a cooling coil, a cold or
hot wall, direct exposure to sun rays, etc. (2) Close proximity of the probe to a steam injector,
humidifier, direct exposure to precipitation, etc. (3) Unstable pressure conditions resulting from
excessive air turbulence.
d) Immerse as much of the probe as possible in the environment to be measured.
e) Prevent the accumulation of condensation water at the level of the sensor leads. Install the
probe so that the probe tip is looking downward. If this is not possible, install the probe horizontally.
5.2 Type D
– through wall mount
Part AC5005 is a flange with compression fitting that is designed to hold the probe of the
HF3 type D when mounted through a wall (see Accessories). The HF3 does not require
any additional support. The AC5005 allows easy installation and removal of the HF3.
5.3 Type W
– surface mount
The transmitter housing can be attached to the mounting wall using screws with an approximate diameter of 3
mm (1/8").