Filter Classification - Airgas.com

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Filter Classification

With the NIOSH 42 CFR 84 Standard, nine classes of filters (three series of filters with three levels of filter efficiency) were developed. The series are referred to as N, R, and P. The three different levels of efficiency are 95%, 99% and 99.97%, against the most difficult size particle to filter.

N - Series Filter: These filters are restricted to use in those atmospheres free of oil aerosols. They may be used for any solid or liquid airborne particulate hazard that does not contain oil. Generally these filters should be used and reused subject only to considerations of hygiene, damage and increased breathing resistance.

N95 Particulate Filter – At least 95%filter efficient when tested with ~0.3 ìm NaCl aerosol.

N99 Particulate Filter – At least 99%filter efficient when tested with ~0.3 ìm NaCl aerosol.

N100 Particulate Filter – At least 99.97%filter efficient when tested with ~0.3 ìm NaCl aerosol.

R – Series Filters: Filters intended for removal of any particle including oil based liquid aerosol. They may be used for any solid or liquid airborne particulate hazard. If the atmosphere contains oil, the R-series filter should be used only for a single shift (or up to 8 hours continuous or intermittent use).

R95 Particulate Filter – At least 95%filter efficient when tested with ~0.3 ìm DOP (Dioctyl Phthalate) aerosol.

P – Series: Filters intended for removal of any particle including oil based liquid aerosols. They may be used for any solid or liquid particulate airborne hazard. NIOSH recommends that respirator manufacturers establish time use limitations for all P-series filters. P-series filters should be used and reused for no more than 40 hours of use or 30 days, whichever occurs first, in atmospheres that contain oil aerosols unless the filter needs to be changed for hygiene reasons, is damaged, or becomes difficult to breathe through before the time limit is reached.When used in atmospheres containing non-oil aerosol, P-series filters should be used and reused subject to conditions of hygiene, damage and increased breathing resistance.

P95 Particulate Filter – At least 95%filter efficient when tested with ~0.3 ìm DOP (Dioctyl Phthalate) aerosol.

P100 Particulate Filter – At least 99.97%filter efficient when tested with ~0.3 ìm DOP (Dioctyl Phthalate) aerosol.

Oil: Any of numerous mineral, vegetable and synthetic substances and animal and vegetable fats that are generally slippery, combustible, viscous, liquid or liquefiable at room temperatures, soluble in various organic solvents such as ether, but not in water.

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