What Is a Dust Meter?
A dust meter is a device used to measure the concentration of dust in a space. In addition to a dust meter, a particle counter is another device that measures particles in a space. The two devices are very similar, but a dust meter can measure higher concentrations.
Dust meters and particle counters differ in the units of concentration they measure and display. A dust meter measures and displays mass concentrations, while particle counters measure and display piece concentrations.
Another difference between the two instruments is the suction speed. For a dust meter used to measure high concentrations, a suction rate of a few liters per minute is sufficient. Particle counters, on the other hand, are used to measure gases with relatively low particle concentrations and require higher suction volumes, with suction rates as high as 100 liters per minute.
Uses of Dust Meters
Dust meters are used to measure relatively high concentrations of dust. PM2.5 is measured in air, so dust meters are used.
In contrast, particle counters are usually used in spaces with lower particle concentrations than dust counters. For example, they are suitable for measurement in spaces with high cleanliness, such as clean rooms in manufacturing plants in the medical, electronic materials, and food industries.
Principle of Dust Meters
A laser is generally used to detect dust. It is known that when a laser is shone on dust if the dust is uniform in shape, color, and other properties, the intensity of the scattered light is proportional to the mass concentration of the dust. The laser dust meter measures the mass concentration of dust by converting the intensity of the scattered light into an electrical signal.
In contrast to the indirect measurement of dust concentration using a laser (relative concentration measurement method), the direct measurement of the mass of particles collected by a filter is called the direct gravimetric measurement method. Compared to measurement using filters, laser measurement has the advantage of requiring only a small amount of suction and a short measurement time. This advantage can be used to measure changes in dust concentration and distribution over time.
However, the relative concentration obtained with laser dust meters is only an indirect measurement based on the assumption that the dust properties are uniform. To confirm the validity of the concentration obtained, a comparison test with the direct gravimetric method was performed.