Casella CEL Microdust 880 IS real time dust monitor - Manual (Page 5)

Microdust 880nm & WinDust Application Software
Handbook HB3255-03
Page 5 of 51
The Microdust 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.
Microdust instruments are available in four range options:-
• 0.001 to 2.500 mg/m 3 and 0. 01 to 25.00 mg/m 3
• 0.01 to 25.00 mg/m 3 and 0.1 to 250.0 mg/m 3
• 0.1 to 250.0 mg/m 3
and 0 to 2500 mg/m
3
• 0.001 to 2.500 g/m 3
and 0.01 to 25.00 g/m
3
All instruments are factory calibrated using a wind tunnel system based on 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, an optional gravimetric or
respirable adapter unit and sampling pump may be used to provide comparative analysis between
gravimetric and real time data.
A 2 line alpha-numeric Liquid crystal display is used to show instrument configuration details,
contaminant levels, logger information and battery condition.
Principle of Operation
In fra R e d
E m itte r (8 8 0 n m )
In fra R e d
D e te c to r
L ig h t S to p
S a m p le
V o lu m e
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
angle to the receiver. By using a narrow angle of scatter, the instrument's sensitivity to variations in
the refractive index and colour of measured particulate is reduced.