Measurement of the performance of free-standing filtering extraction units used in the woodworking industry

摘要

The filtration efficiency of free-standing dust extractors fitted with filter bags of various types and challenged with wood dust of various grades has been measured. During each test, the air pressure inside the filter bag, the extractor air flow rate and the concentration of dust penetrating the filter bag were monitored. Needlefelt filter bags allowed a limited quantity of dust, usually at a concentration well below the maximum exposure limit(MEL)of 5 mg m~-3, to penetrate when they were clean and improved greatly as they became loaded with dust. Filter bags made from woven cotton let more dust through.