Respirator filter media studies for protection against particulate contaminants

Respirators play an important role in preventing internal contamination in nuclear facilities. Apart from the requirements such as ease of breathing (breathing resistance), hygiene aspects etc, respirator filter media should have the ability to trap the specified contaminant (removal efficiency) to the desired level. The study was aimed to carry out pressure drop measurements across the filter for various flow rates and estimation of filtration efficiency of various respirator filter media for particulates. The results of the studies indicate that the efficiency of the HEPA filter media and HEPA plus carbon granules filter media are 99.97 and 99.99 respectively for 0.3 μm particles and the efficiency increases further for particles ranging from 0.25 to 1 μm. HEPA plus carbon granules filter media is found to show higher filtration efficiency as well as lower pressure drop compared to HEPA filter media. (author)