Casella CEL Software for the Microdust dust monitor - Manual (Page 50)

If this is not done, the clean purge air emerging from the measurement
chamber will prevent entry of particulate matter.
5.2.2 Cleaning
When it is suspected that lens contamination has occurred (recognised by
the inability to zero or calibrate the instrument correctly), attach the air purge
bellows to the probe inlet and pump vigorously with the measurement
chamber open. Any dust deposited on the surface of optical components
should be blown clear.
To prolong the serviceable life of the instrument, it is recommended that this
operation be performed after each use.
If the lenses become so heavily contaminated that using the air purge pump
is ineffective, the instrument should be returned to Casella CEL for cleaning
and re-calibration. Note that the Warranty does not extend to cleaning or
general servicing of the instrument.
5.3 Fault Finding Tips
The MicroDust pro contains no user serviceable components. Repairs should
be performed only by authorised personnel.
If an electrical fault is found, or a fault persists after carrying
out the recommendations in the service hint, return the
instrument to Casella CEL Ltd for repair.
Fault Symptom Possible Cause Service Hint
Instrument does not
switch ON
Battery discharged, or
failing to charge. Confirm
charger indicator is lit
Recharge or replace
battery if necessary.
Use external power supply.
Probe always reads zero Fault with Infrared
transmitter or receiver.
Check the probe
connection.
Continuous “over range”
indication
Optical misalignment due
to mechanical shock.
Excessive contamination.
Return the instrument to
the service department for
optical alignment, cleaning
and re-calibration.
Unstable or drifting zero in-
dication with probe cover
on
Sample chamber may be
contaminated by dust or
fibre.
Use the bellows pump to
purge the probe with clean
air prior to setting zero.
The probe cover should be
open slightly when
purging, to allow venting of
purge air.
Probe contamination
message is displayed
Excessive contamination of
probe or optical
misalignment due to
mechanical shock.
Purge the probe with clean
air from the bellows pump.
Page 50 of 60
Maintenance
& Servicing MICRODUST pro Aerosol Monitoring System &
WinDust pro Application Software - Handbook