Casella CEL Software for the Microdust dust monitor - Manual (Page 43)

4. SAMPLING ACCESSORIES
When used in static monitoring applications, the sampling probe’s
measurement chamber should have some form of aspiration, either in the
form of an Apex (or Vortex) sampling pump or a fan aspirator unit.
Maintaining airflow through the probe eliminates potential errors due to
orientation of the probe inlet and size selectivity.
The gravimetric and respirable adapters incorporate 25 or 37 mm filter
cassettes and provide a convenient method of gravimetrically calibrating
MicroDust pro instruments.
4.1 Gravimetric Adapters
The gravimetric adapter units may be used in conjunction with a sampling
pump to enable all sampled particulate matter to be drawn through the probe
measurement chamber and then deposited on to a 25 or 37 mm filter. There
are three gravimetric adapter options available.
Total Suspended Particulate (TSP)
All sampled particulate is monitored in real time and then deposited
on to a sample filter. The design provides no size selective
characteristics.
Respirable (4 µm)
The respirable adapter design incorporates a Cyclone size selective
unit. Only the respirable fraction of particulate passes through the
probe and is deposited on to the filter.
PUF (Polyurethane Foam Filter)
The PUF gravimetric adapter uses foam filter inserts to provide size
selective sampling characteristics. Filters are available for PM 10 ,
Respirable (4 µm) and PM
2.5
size fractions.
All components fit together using “O” rings for sealing. These should be
checked for signs of damage, which may result in erroneous readings due to
air leakage. The adapters enable standard gravimetric techniques to be used
and provide a cross check between the readings of the MicroDust pro and a
weighed sample.
If errors are found between the instruments reading and the gravimetric
value, a correction figure can be determined and applied to give a closer
correlation of the two readings. (Please refer to Calibrating for a Specific Dust
Type in Section 2.3.2.)
The sampling probe should be inserted into the adapter block and correctly
aligned over the sample inlet. The locating spigot of the Cyclone, TSP inlet
tube or PUF filter holder should be inserted into the probe’s sample inlet so
that the complete assembly cannot rotate or move laterally on the probe.
Page 43 of 60
Sampling
Accessories
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