Casella CEL Software for the Microdust dust monitor - Manual (Page 8)

The MicroDust pro is able to exhibit the highest degree of sensitivity for
particle sizes within the respirable domain, while the detachable probe allows
readings to be taken in relatively inaccessible areas.
The MicroDust pro offers measurement over four ranges:
¤ 0.001 to 2.500 mg/m 3
¤ 0.01 to 25.00 mg/m 3
¤ 0.1 to 250.0 mg/m 3
¤ 1 to 2500 mg/m 3
All instruments are calibrated at the factory using reference test dust (ISO
Fine 12103-1 A2, equivalent to Arizona Road Dust). These facilities allow the
calibration concentration to be determined using traceable gravimetric
analytical techniques. An optical calibration element is supplied as a reference
to confirm the factory calibration point. For optimum calibration against local
dust conditions, a sampling pump and optional gravimetric or respirable
adapter unit may be used to provide comparative analysis between
gravimetric and real time data.
The high definition liquid crystal display is capable of showing both text and
graphical information. It shows instrument configuration details, contaminant
levels, logger information and battery condition.
1.2 Principle of Operation
The instrument uses a modulated beam of infra-red light projected forward
into a measurement chamber.
Under clean air conditions all light is prevented from reaching the receiver by
a light stop. When dust particles enter the sample volume, the light beam is
scattered forward within a narrow (12 - 20 o ) angle to the receiver.
By using this narrow angle of scatter, the instrument’s sensitivity to variations
in the refractive index and colour of measured particulate is reduced.
Excellent linearity is achieved right up to 2500 mg/m
3 as shown in Figure 3.
Figure 2: The sampling probe
Infra Red
Emitter
Infra Red
Detector
Sample
Volume
Light Stop
00009
Page 8 of 60
Description MICRODUST pro Aerosol Monitoring System &
WINDUST pro Application Software - Handbook