ROTRONIC HM4 - Manual (Page 18)

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 18 of 41
Document Title
© 2014; ROTRONIC AG E-M-HM4-V0_08
4.1.6 Sensor Cleaning (RoHumiClean)
Sensor cleaning can take place in three time intervals.
Daily
Weekly
Monthly
The duration of the cleaning cycle is freely selectable in minutes. The cleaning temperature can be set up to
150 °C. No measurements are carried out during the cleaning phase. The last measured value is frozen until
the cleaning cycle is finished.
Stop Response
After cleaning, the sensor needs to cool down. No values are measured for a time of five minutes after
cleaning until this state has been reached.
Working Principle
Heating of the sensor up to 150 °C removes volatile and non-volatile contaminants. The sensor is thus cleaned
and, if water has entered the housing, dried completely. This prevents electrochemical corrosion.
Note:
When the sensor is heated to 150 °C, a drop of water on the surface of the sensor evaporates in about three
minutes.
A minimum power supply of 15 VDC is needed to initiate sensor cleaning manually with the HW4 software. If
this is not available in the field application, the function is still activated, but might not reach the required
temperature. The limit values are as follows:
Power supply: 15 VDC attainable heating temperature: 150 °C
Power supply: 10 VDC attainable heating temperature: 100 °C
Power supply: 5 VDC attainable heating temperature: 35 °C
The function can be enabled/disabled with the HW4 software.
DRAFT