PARTICLE SHEDDING CHARACTERISTICS OF MEMBRANE FILTERS UNDER PULSED-FLOW CONDITIONS IN LIQUID FILTRATION

摘要

Microporous membrane filters are extensively used in the production and delivery system of deionized water and ultrapure liquid chemicals to assure the low level of paniculate impurity. A pressure shock to the filter during the operation of the liquid production and delivery' system induces particle shedding from the filler. The membrane filters used commonly were tested for particle shedding at different pulsed-flow conditions. The flow pulses of various strength were produced by turning on and off the valves at the downstream and upstream of the test filters. The results showed that the particle shedding of the membrane filters depended on the strength of the flow pulse, the duration of the flow stopping time, and the duration of the pulse. The flow pulse due to the pressure release (turning on the downstream valve) induces less particle shedding than the pulse due to pressure exertion (turning on the upstream valve). A soft-open valve operation mode is recommended to reduce the particle shedding.