Casella CEL Environmental enclosure for Microdust - Manual (Page 5)

3.6 Service Interval for Key Components
The equipment is designed and engineered for long and dependable service
but as a precision instrument it should be given the best of care. The typical
service intervals for key sampler components are as follows.
Valves Part No 101189A 1500 hours,
Pump diaphragm Part No 102164B 1500 hours,
Damper assembly Part No B8351/7 1500 hours,
Eccentric 2.85 stroke Part No 158008A 1500 hours,
Bearing Part No BRE42 1500 hours,
Motor Part No 104056B 3000 hours.
For rapid first line maintenance of the samplers, it is recommended that the
following stock of modular sub-assemblies also be purchased.
Diaphragm pump Part No 151312A.
3.7 Fault Finding
SYMPTOM POSSIBLE CAUSE SERVICE HINT
PUMP does not run,
(green LED not lit).
BATTERY fully
discharged.
RECHARGE.
FLOW adjustment
set too low.
Turn FLOW
CONTROL up.
WIRING LOOM
disconnected at
some point.
LOCATE & re-solder.
Fault on JOINT. REPLACE circuit
board.
PUMP does not run,
(green LED is lit).
Eccentric BEARING
SEIZURE.
REPLACE bearing.
Motor SHAFT
SEIZURE.
REPLACE motor.
Broken WIRE. REPAIR connection.
Motor runs but PUMP IN-
OPERATIVE
GRUB SCREW
securing eccentric to
motor shaft LOOSE.
RE-TIGHTEN.
Health and Safety Executive publication MDHS 14/3. The foam filter
specifications and dimensions determine the desired aerosol size selection
characteristics and eliminate particle sizes greater than PM
10,
PM
2.5
or
Respirable (4 µm) as appropriate. The larger particles become trapped and
collect within the foam matrix, whilst all particles below these “cut-off
points” pass through the PUF filters and enter the measurement chamber,
where the real time mass concentration is established.
After passing through the Microdust pro, particulate matter is deposited on a
37 mm filter which may be used for gravimetric or chemical analysis.
Remember however, although the Environmental Enclosure has been
designed to monitor particulate fraction concentrations in a variety of
environments, it does have some operating limitations. The instrument is
not designed to operate continuously out of doors for long periods of time (in
the order of days or weeks).
Due to the light scattering principle used within the instrument, any moisture
which individual particles attract at periods of high humidity or temperatures
approaching “dewpoint” will be “seen” by the instrument as larger particles.
This biases results towards greater concentrations. Also, during these
periods, any air being drawn through the instrument which is high in humidity
may condense on the optics and distort the light beam, producing spurious
results.
With this limitation in mind, it is recommended that the Microdust pro not be
used to monitor continuously for days at a time. Any application requiring
this type of monitoring regimen, will need a particulate monitor with internal
heater, to drive off any water vapour within the incoming air stream, thus
eliminating erroneous readings.
The Casella Ambient Particulate Monitor (APM950) is considered the best
tool for this job and can run continuously and unattended for months at a
time. Please contact CASELLA CEL or your distributor for more information.
1.2 System Overview
The internal configuration of the Environmental Enclosure is shown in
Figure 2.The system incorporates a sampling pump to draw the sample air
through the inlet pipe at a user selected flow rate. PUF filters are designed to
operate at a flow rate of 3.5 litres/minute. The inlet head is designed to
prevent the ingress of insects and other large foreign objects. A dust cap is
provided to seal the inlet port on the case lid whenever the inlet tube is
removed for transit purposes.
Size selection of the sample stream is performed by passing the sample
through a PUF foam filter appropriate to the chosen sampling strategy,
Page 16 of 20 Page 5 of 20
Introduction VORTEX Pump
ENVIRONMENTAL ENCLOSURE
For MICRODUST pro - User Manual ENVIRONMENTAL ENCLOSURE
For MICRODUST pro - User Manual