SAND FILTER Russian patent published in 2000 - IPC

FIELD: filtering systems, possibly used at working of oil and gas wells. SUBSTANCE: filter includes concentrically arranged outer, intermediate, inner tubes and adaptor. Inner tube has openings and filtering network in the form of auger arranged inside it and secured in front of openings arranged along helical line. Outer and inner tubes are mutually joined in their upper portions by means of tangential pipe branches. Inner and intermediate tubes are mutually joined in their lower portions by means of tangential branch pipes oriented opposite relative to above mentioned branch pipes. There are stoppers in annular gap between intermediate and inner tubes in their upper portions and in upper and lower portions of inner tube. Outer tube has elastic rings in upper portion and stopper - in lower portion. EFFECT: increased useful life period of filter due to elimination of clogging of filtering network. 3 dwg