A self-cleaning vacuum head is disclosed which has the ability to discriminate between particles of different size, or the ability to separate fluids from particulate matter. The invention has two relatively moving surfaces which provide a changing locus of vacuum so that particles drawn against the...http://www.google.es/patents/US5076919?utm_source=gb-gplus-sharePatente US5076919 - Self-cleaning vacuum filter with relatively moveable surfaces for recovering oil from beaches
Self-cleaning vacuum filter with relatively moveable surfaces for recovering ...
