Casella CEL Indoor air quality monitor - Manual (Page 35)

Sensor Specifications
12.6 Airborne Particulate
Monitor
The MicroDust pro is a versatile
instrument designed to measure the
concentration of airborne dust particles.
It uses a beam of infra-red light projected
forward into a measurement chamber.
The light within the chamber is blocked
from reaching the receiver by a modified
Woods horn. When dust particles pass
through the measurement chamber, the
light beam is scattered forward within a
narrow angle to the receiver. This narrow
angle of scatter reduces the instrument’s
sensitivity to variations in the refractive
index of measured particles.
Optional adapters are available for use
with the MicroDust pro to ensure accurate
measurement when static site monitoring,
as well as to obtain dust samples.
The MicroDust pro must be mechanically aspirated when used in fixed-site
applications. A fan-driven Aspirating Unit can be used to draw all suspended
particles through the probe for ambient monitoring. If however, a gravimetric
filter is required for further analysis, then one of our gravimetric adapters can
be used. This, in turn, is connected to a personal sampling pump such as the
AFC124, which is a self contained unit with internal rechargeable batteries.
Two dust sampling adapters are available. The Respirable Dust Adapter uses
the cyclone principle of dust separation to draw only the respirable fraction of
dust particles through the measurement chamber. Samples of respirable dust
can be taken by incorporating a push-fit cassette-type filter holder. The
Gravimetric Adapter provides a total dust sample, using either 25 mm or 37
mm membrane filters, which can be used to check the calibration of the
instrument for a pre-defined aerosol monitoring application. Both adapters fit
and lock on to the probe using “O” rings to seal the critical areas. The probe
clip that is attached to the unit has a tripod mounting bush to enable fixed site
monitoring.
Specification
Measuring Ranges 0.001 - 2.5 mg/m
3
, 0.01 - 25 mg/m
3,
0.1 - 250 mg/m
3
& 1.0 - 2500 mg/m
3
Response Time Adjustable between 1 S and 60 S
Resolution 0.001 mg/m
3
Zero Stability <2 µg/m
3
/
o
C
Span Stability ±0.7%/ o C
Operating Temperature 0 to 50
o
C
Power Requirement 4 x AA / MN1500 Alkaline or NiCd cells
Page 35 of 42
MICROTHERM indoor air quality &
WinIaq Application Software - User Manual