Mist collectors and fume collectors reduce the amount of mist, aerosols and fumes in the workplace atmosphere. Smoke and fume is sub micron particulate created by processes such as welding, rubber and plastic processing, high speed machining with coolants, tempering, and quenching.
Mist collectors and fume collectors may be available in a number of different models. Ambient units are free-hanging systems for use when applications limit the use of source-capture arms or ductwork. Collector booths require no ductwork, and allow the worker greater freedom of movement. They are often portable. A downdraft table is a self-contained portable filtration system that removes harmful particulates and returns filtered air back into the facility with no external ventilation required. Portable units are for collecting dust, mist, fumes, or smoke at the source. Stationary collectors are not portable and may be large self-contained units such as a baghouse.
Applications for mist collectors and fume collectors are numerous. They can be used for abrasives, coolant smoke and mist from metal finishing and forming processes, machining oil mists, explosive dusts, mists, and/or fumes, fine powders, general cleaning, toxic mist, fume, or smoke, and welding fumes or dust; these may include flux recovery systems.
The filtration system used is often dependent on the application. A baghouse is an air pollution abatement device used to trap particulate by filtering gas streams through large fabric bags. They are typically made of glass fibers or fabric. Filter cartridges are made out of a variety of synthetic fibers and are capable of collecting sub-micronic particles without creating an excessive pressure drop in the system. Filter cartridges require periodic cleaning. A cyclone separator is an apparatus for the separation, by centrifugal means, of fine particles suspended in air or gas. An impinger system is a device in which particles are removed by impacting the aerosol particles into a liquid. Modular media type units combine a variety of specific filter modules in one unit. These systems can provide solutions to many air contaminant problems. A typical system incorporates a series of disposable or cleanable pre-filters, a disposable vee-bag or cartridge filter. HEPA or carbon final filter modules can also be added. Various models are available, including free-hanging or ducted installations, vertical or horizontal mounting, and fixed or portable configurations. Electrostatic precipitators are a type of air cleaner, which charges particles of dust by passing dust-laden air through a strong (50-100 kV) electrostatic field. This causes the particles to be attracted to oppositely charged plates so that they can be removed from the airstream. A wet scrubber, or Venturi scrubber, is similar to a cyclone but it has an orifice unit that sprays water into the vortex in the cyclone section, collecting all of the dust in a slurry system. The water media can be recirculated and reused to continue to filter the air. Eventually the solids must be removed from the water stream and disposed.
The power of the mist collector or fume collector system is usually specified in horsepower. The motor may be powered by AC single phase, AC three phase, DC power, compressed air, diesel, natural gas, or gasoline.
Mist collectors and fume collectors may also be specified by the airflow, storage capacity, or minimum particle size filtered.
Features that may be offered with some mist collectors or fume collectors are collection arms for source collection, a continuous duty cycle, HEPA or ULPA filters, or an instrument panel for user operation.
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