SKC Limited EPAM-5000 - Manual (Page 14)

Real-Time Dust Monitoring Principles
Principles • The SKC EPAM-5000 uses the principle of near-forward light scattering of
an infrared radiation to immediately and continuously measure the
concentration in mg/m
3 of airborne dust particles.
• This principle utilizes an infrared light source positioned at a 90-degree
angle from a photo detector.
• As the airborne particles enter the infrared beam, they scatter the light. The
amount of light received by the photo detector is directly proportional to the
aerosol concentration.
• A unique signal processes internally and compensates for noise and drift.
This allows high resolution, low detection limits and excellent base line
stability.
Figure 1.5. Diagram showing the principle of near-forward light scattering used in the SKC
EPAM-5000.
Light Scattering vs. Gravimetric Filter
0
0.2
0.4
0.6
0.8
1
0 0.2 0.4 0.6 0.8 1
Gravimetric Filter Weight
Relative Optical
Response
ARD = Arizona Road Dust
RTD = Real-Time Dust
ARD
0.1 ARD
Filter
Figure 1.6. Graph illustrating the principle of near-forward light scattering.
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