Filters

A HEPA (High Efficiency Particulate Air) filter is described as the “workhorse” of the cleanroom. Their efficiency is rated at 99.97% on 0.3 micron particles (i.e. only three out of 10,000 particles, 0.3 in size can penetrate through the filter). HEPA filters are constructed of a single sheet of filter medium folded many times, with the pleats separated from each other by corrugated anodized aluminum elements called separators. The medium and separators are housed in a frame, usually made from anodized aluminum. By pleating the media a large amount of filter surface area can be compacted in a small volume. The filter medium is a collection of randomly oriented fibers of varying lengths and diameters compressed into mats.

A ULPA (Ultra low Particulate/Penetration Air) filter is more efficient than HEPA filters. ULPAs’ are efficient to 99.99999% for 0.12 micron particles and more expensive. These filters are constructed and will function in the same manner as a HEPA filter. The difference is in the filter medium, it has a higher proportion of smaller fibers and the pressure drop is a little higher.

If you have questions about which type of filtration is best suited for your application please call at 408.842.2400.