Backwashing filter candles comprises forcing constantly maintained liquid layer through candle by compressed air pulses

摘要

The candle (4), seated in a support plate (3), has an integrally molded, or separately fitted, tube extending into the upper opening. A radial gap is formed between the tube and the bore of the candle that will determine the thickness of a layer of cleaning fluid passed into the gap. Compressed air entering the tube as timed pulses forces the layer uniformly through the candle wall. The frequency of the pulses is chosen so that the layer of cleaning fluid can re-establish itself between pulses. The air enters at a lower level than the cleaning fluid.