ROTRONIC HygroLab - Manual (Page 29)

IN-E-HyLab-V4_11
Rotronic AG
Bassersdorf, Switzerland
Document code Unit
Instruction Manual
Document Type
HygroLab bench top indicator version 4:
instruction manual
Document title
Page 29 of 51
© 2006; Rotronic AG IN-E-HyLab-V4_11
10 Maintenance of the ROTRONIC probes
Cleaning or replacing the dust filter
Most ROTRONIC probes come with one of the following types of dust filter: (a) protective
metal base with a removable filter cartridge or (b) plastic slotted cap with built-in (not
removable) filter element.
Depending on the conditions of measurement, the filter should be checked from time to time. If
the probe has a removable filter cartridge, this can be easily removed for cleaning.
If the probe has a plastic slotted cap with a built-in filter element, cleaning should be done
without removing the filter from the probe. In that case, do not use detergents, solvents or
other strong chemicals. Either brush the filter or use a little bit of clean water.
Corroded, discolored or clogged filters should be replaced. If the probe has a removable
cartridge, simply replace the cartridge (leave the metal base on the probe).
If the probe has a plastic slotted cap with built-in filter element follow these instructions:
1) Unscrew the filter from the probe and pull it straight away, in the alignment of the probe, so
as not the catch the humidity and temperature sensors.
2) Before putting on a new dust filter, check the alignment of both sensors with the probe. The
wires that connect the sensors to the probe are very thin and bend easily. If necessary, correct
the alignment by tapping the sensor very gently with a smooth object such as a small plastic
rod. Do not use sharp pliers or tweezers as this could puncture the sensor and do not pull
hard on the sensor.
Periodic calibration check
Long term stability of the ROTRONIC Hygromer humidity sensor is typically better than 1
%RH per year. For maximum accuracy, calibration of the probe should be verified every 6 to
12 months. Applications where the probe is exposed to significant pollution may require more
frequent verifications.
Both the Pt 100 RTD temperature sensor and associated electronics are very stable and
should not require any calibration after the initial factory adjustment.
For routine calibration checks, the probe should be verified at one or two values of humidity.
For more details, see Probe calibration basics and Functions – ADJUST M.PT.