SKC Limited EPAM-7500 - Manual (Page 14)

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Real-Time Dust Monitoring Principles
Principles • The EPAM-7500 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 Haz-
Dust..
Figure 1.6. Graph illustrating the principle of near-forward light scattering.
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Gravimetric Filter Weight
Light Scattering vs. Gravimetric Filter
ARD
0.1
ARD = Arizona Road Dust
RTD = Real-Time Dust
ARD
Filter