Separation efficiency of a wood dust collector-field measurement using a fluorescent aerosol

Given the dangerous nature of the dust emitted in the wood industry, the quality of the recycled air in the work premises after cleaning must be strictly controlled.A method of measuring the efficiency of a wood dust collector as a function of the particle diameter has been developed using a fluorescein tracer aerosol generated upstream of the equipment. The separation efficiency is determined from the particle size mass distribution of the tracer, both upstream and downstream, measured by means of two cascade impactors. The mass efficiency measured by tracer technique was compared on a test rig to the number efficiency measured using a reference method based on optical counting. The agreement between the two efficiencies is quite good; nevertheless, the tracer method leads to results that are slightly below those obtained using the reference method. The method was applied to measure the efficiency of a 11 500 m(3) h(-1) wood dust collector. The results are presented along with those obtained from a sample of plane filter media making up the bags of the dust collector.