AFS-G1
page 8
AFS-G1 K04/1019
9. Maintenance
The measuring element is normally maintenance-free in pure ambient air.
Aggressive media containing solvent can cause measuring errors and failure,
depending on the type and concentration. As with almost all humidity measuring
elements, deposits that eventually form a water-repellent film over the sensor are
harmful. Such substances are resin aerosols, lacquer aerosols, smoke deposits,
etc. The water-resistant property of the measuring elements allows cleaning to be
carried out in water. Solvents cannot be used for this purpose. A light-duty
detergent is recommended, but any residue should always be washed out
thoroughly. A special process ensures that sensors have good long-term stability.
Regeneration is not necessary, but is also not harmful.
9.1. Cleaning Process
1. Dip the sensor tube into a receptacle containing clean water (20 °C) and, with
a gentle rotating motion, disperse the dirt deposits. If the dirt contains grease
deposits, it is recommended that a mild detergent be added to the water.
Attention! Do not brush or treat with any other cleaning utensils.
Only the sensor tube should be immersed - not the housing.
The sensor tube is open to the housing interior (0.8 mm hole)
2. As mild detergents are known to contain chemical substances, rinse carefully
after cleaning. Cleaning residue will impair the measured result.
3. Air drying. Where a measuring element is moistened with water, the device
indicates 100 % relative humidity. If necessary, it is possible to carry out
sensitive recalibration at the adjusting spindle at the end of the sensor. This
should only be done where there are large deviations. Slight movement of the
adjusting spindle of a wet element will cause the measured value in the dry
area to be change greatly. Here, there is an intensifying effect of the
linearisation (factor 6). Indications of 98 – 100 % relative humidity at the wet
element are adequate. The accuracy in the dry area must be determined
under normal climatic conditions.
Attention! The measuring element must not be dried using warm or
hot air (hair dryer).
Cleaning should be carried out for no longer than 10 minutes.
