6.2. MAINTENANCE METHODS
6.2.1 Interior and exterior cleaning
The cabinet interior and exterior should be kept clean and free from deposits.
The exterior surface is easily cleaned with warm soapy water. When cleaning any
stainless steel surface do not use any cleaning agent containing chloride or hypochlorite
ions as these will cause corrosion.
6.2.2 Cleaning of cabinet drain(s)
Either one or two drains are situated centrally in the base of the treatment chamber.
Access to the treatment chamber involves the removal of the working chamber base.
Remove the front cover and slide out the working chamber base. Any accumulation of
contaminants from the test sample can cause the treatment chamber to block. The drain
should be checked regularly to ensure that particles are not collecting around it.
6.2.3 Inspection and replacement of the wet wick(s)
Access to the sensors and wicks is through the sliding panel in the right hand wall of the
working chamber. See fig. 4 for the position of the wet and dry bulb sensors.
The accuracy of all wet and dry bulb systems for the control of relative humidity is totally
dependent on the wet wick. The rate of evaporation from the wick determines the
cooling of the sensor and hence the temperature differential (wet bulb depression) of the
control or recording instrument. Adherence to the following notes is recommended for
all serious work at controlled relative humidities.
a) Wick must be clean - handle with care and clean hands - store in a clean place - change
regularly (once a month).
b) Wick must cover the entire exposed length of the sensor ie: extend well beyond the
sensitive tip and fit tightly to the sensor.
c) Wick must be the correct length to fit over the sensor and well down into the rubber
wick reservoir, to prevent the high speed, necessary for correct evaporation, from
blowing the wick out of the reservoir.
d) If wicking quality of the material is suspect, test by cutting off 1 cm of dry material
and dropping into a cup of distilled water. Sample should wet and sink within 2 seconds.
Often wicking quality can be restored by boiling for a few minutes in clean distilled .
water.
Figure 4.
RECORDER CONTROLLER
DRYRT WETRT WETRT DRYRT
/white\ /white
Temperature sensor positions (as viewed from inside working chamber)
20