ROTRONIC HM4 - Manual (Page 20)

E-M-HM4-V0_08
ROTRONIC AG
Bassersdorf, Switzerland
Document Code Unit
HM4 Humidity and Temperature Probe with
Heated Sensor
Instruction Manual
Document Type
Page 20 of 41
Document Title
© 2014; ROTRONIC AG E-M-HM4-V0_08
5 Mechanical Installation
5.1 General
Relative humidity is very dependent on temperature. Proper measurement of relative humidity requires that the
probe and its sensor have exactly the same temperature as the environment that is to be measured. For this
reason, the location where the probe is installed can have a significant influence on the performance of the
device. The following guidelines should guarantee good device 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 1 metre/second (200 ft/minute)
facilitates adaptation of the probe to changing temperature.
c) Avoid the following:
(1) Placing the probe too close to heating elements, cooling coils, cold or hot walls, in direct sunlight,
etc.
(2) Placing the probe too close to steam injectors, humidifiers, in direct precipitation, etc.
(3) Unstable pressure conditions resulting from high air turbulence.
d) Immerse as much of the probe as possible in the environment to be measured.
e) Prevent an accumulation of condensation water in the area of the sensor leads. Install the probe
so that the probe tip points downwards. If this is not possible, install the probe horizontally.
DRAFT