Casella CEL Microdust Pro real time dust monitor - Manual (Page 37)

MicroDust Pro Aerosol Monitoring System
37 Casella CEL
6 Sampling Accessories
When you use the MicroDust Pro instrument in static monitoring applications,
you should use some form of aspiration with the sampling probe. This can be
either a TUFF (or Apex) sampling pump or a fan aspirator.
By maintaining an air flow through the sampling probe you can eliminate
possible errors caused by the orientation of the probe’s inlet and size selectivity.
The gravimetric and respirable adapters include 25 mm or 37 mm filter
cassettes, and provide a convenient method of calibrating the instrument.
6.1 Gravimetric adapters
The gravimetric adapter units draw particulate matter through the sampling
probe’s measuring chamber and deposit it on a 25 mm or a 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
onto a sample filter. The design does not allow selection based on
particulate size.
• Respirable (4 µm)
The respirable adapter design includes a Cyclone size-selective unit.
This means that only respirable particulate passes through the sampling
probe and is deposited onto the filter.
• Polyurethane Foam Filter (PUF)
The PUF gravimetric adapter uses foam filter inserts to provide size-
selective sampling. Filters are available for PM
10
, Respirable (4 µm), and
PM
2.5
fractions.
These adapters allow you to use standard gravimetric methods to cross-check
readings from the MicroDust Pro instrument against a weighed sample.
All components of these adapters fit together using O-ring seals. You should
check these regularly, and you should fit new O-rings if there are any signs of
damage. Damaged O-rings can cause measurement errors due to air leakage.
If errors exist between the instrument’s measurements and the true gravimetric
value, you can determine and apply a correction factor to the instrument’s
measurements. Refer to “
Calibrating the instrument for a specific type of
particulate ” on page 25 for instructions to do this.
Align and insert the sampling probe into the adapter block. Insert the adapter’s
locating spigot into the probe’s inlet so that the adapter cannot rotate or move
on the probe.