Laboratory testing of air cleaners for removing indoor contaminants

With the rapidly growing consumer markets for air cleaners, product performance evaluations are needed to assist the selection by consumers as well as design and manufacturing. VOCs (and odors) and particulates are two major contaminant categories for which many air cleaners are claimed to have good removal efficiency. However, no standard method for combined VOC and particulate removal testing exists, and published data are limited. In this study, a chamber "pull-down" method and procedure for concurrent testing of VOC and particle removal was developed. Eight air cleaners (including 6 portable and 2 in-duct devices) were tested accordingly with a mixture of 8 representative VOCs and potassium chloride (KC1) particles in a 24.1m ³ stainless steel chamber. Their initial performances were evaluated in terms of clean air delivery rate (CADR), removal efficiency and watts/CADR. Ozone generation rate (if any) was also estimated. These air cleaners cover the major off-the-shelf technologies (mechanical filtration, electrostatic precipitator, sorption filtration, ionizer, etc.). The test procedure and data analysis method worked successfully, especially for portable air cleaners for which the airflow is typically less than 400 CFM. Results indicate that the ionizer had no significant effect on VOCs and very modest effect on particulate removal, and generated ozone contamination. The other products/technologies evaluated had significant effects on particulate and VOCs removal although efficiencies varied from product to product. Based on test results, the qualitative relationships between performance and product design (technology selection, flow arrangement, etc.) as well as contaminant properties (particle size, vapor pressure of VOC, etc.) are discussed. The applicability and uncertainty of the developed test method are also briefly analyzed.