What is the difference between ASHRAE 52.1 and 52.2?
Standard 52.1-1992: Consists of two tests, the atmospheric dust spot efficiency test and a dust arrestance test. The arrestance test quantifies filter efficiency by mass of particles removed or ‘arrestance’ and is generally only used to measure performance of prefilters or low efficiency filters – efficiencies measured by weight give little indication of their performance for the smallest, lightest particles (the most respirable and hazardous). The atmospheric dust spot efficiency test is based upon the amount of stain or discoloration that appears on a filter when subjected to specific test conditions and is not based on a specific particle size. The atmospheric dust spot efficiency is commonly shortened and referred to as ASHRAE efficiency. Standard 52.2-1999: This test method actually counts the number of particles of varying sizes before and after a filter to determine its true efficiency to filter out particles of various size ranges by count. Standard 52.2 testing measures effici
