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Suspended particles in the air are
sampled at 40 ACFM through the circumferential inlet of the size selective
inlet. The symmetrical design insures wind-direction insensitifity, and
the inlet design and internal configuration makes the collection efficiency
independent of the wind speed from 0 to 36 km/h. The particles are then
accelerated through multiplecircular impact nozzles.
By virtue their large momentum, particles larger than 10 µm impactor
cut-point impact onto the greased impaction surface. The PM-1ß particles
smaller than 10 microns are carried vertically upward by the air flow
and down multiple vent tubes to the 8"x10" hi-vol. filter, where
they are collected.
The large particles settle out in the impaction chamber on the collection
shim and are removed/cleaned during prescribed maintenance periods. The
quartz fiber high-vol filter is weighed before and after sampling. The
weight increase is the mass of particles smaller than 10 µm.
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