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Filtration Table of Contents
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Filter Suppliers
Distribution of Particle, the chart given
below, shows the
distribution of particles (by weight percent) in atmospheric
air as a function of particle shape. Variations in particle
shape, mean particle size, particle size range, and
concentration affect filter life, maintenance costs, and
operational effectiveness. The size range of various types of
particles, the technical nomenclature of various types of
aerosols, and the applicability of various types of air
cleaning devices as a function of particle size are shown
below . A major source of the lint often found on filters is
derived from the abrasion of clothing as people move about.
In addition, a person at rest gives off more than 2.5 million
particles (skin, hair, etc.) and moisture droplets/minute in
the size range of 0.3 to 1 µm.3 Process-generated aerosols
fall into two general size ranges. Those produced by
machining, grinding, polishing, and other mechanical
operations are generally large, (from 1 to several hundred
µm), according to the nature of the process, and can be
removed effectively by common air filters or other
conventional air cleaning techniques. The other size range
includes those produced by evaporation/condensation and other
chemical operations, which generate droplets and solid
particles that are often sub micrometer-sized. These aerosols
are more difficult to separate from air or gases, requiring
collectors such as HEPA Air filters. Ultra Low Penetration Air (ULPA)
filters provide a higher cleaning efficiency (up to 99.9999
percent for sub-micrometer particles). [Note: A need for this
level of efficiency is rare for industrial applications. The
media used in ULPA filters is weaker than that used in HEPA
Air filters, a factor that must be considered for any application
of ULPA filters to air cleaning system or other applications
where durability and reliability are concerns.]
Characteristics of atmospheric and
process-generated particulates, fumes, and mists and
effective range of air cleaning equipment.
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