Performance characteristics of soaked air filters

Several studies have shown that supply air filters in office buildings, schools etc. occasionally get wet due to weather impacts. The aim of this study was to investigate whether performance characteristics, such as pressure drop across the filter and filtration efficiency, change when two different kinds of air filters become soaked and dried. The filters used, were a fiberglass bag filter and a plastic fiber bag filter, each of filter class F7. The study showed that getting wet did not affect the shape of the dried filter material of plastic fibers. Therefore, neither the pressure drop nor filtration efficiency changed. Instead, the material of the fiberglass filter transformed its structure from wadding-like to papery. Hence its pressure drop clearly increased and the filtration efficiency improved.