Patent ID: 8002983

Claim:
A strainer device, comprising: a tubular main chamber with a hollow interior with a top and a bottom and a longitudinal axis that is generally vertically oriented; a generally horizontal inlet with a tangential inlet flow nozzle; a generally horizontal outlet coupled to the main chamber, wherein a fluid flow path is defined from the inlet to the outlet through the hollow interior of the main chamber; a collection area at the bottom of the main chamber, wherein the collection area is offset from the flow path; a pipe internal to the main chamber and with the inner wall of the main chamber, defining an annular flow path from the inlet, downwards from the inlet and then upwards within the pipe, the pipe having at least one external helical guide vane to impart a swirling motion to the fluid in its downwards flow; a distributor connected to the top of the main chamber with a back flush valve to couple the distributor selectively to a flushing fluid source to provide a flow of flushing fluid into the main chamber; said at least one helical guiding vane on the exterior of the pipe and, a screen assembly positioned within the hollow interior in the flow path between the inlet and the outlet and between the distributor and the collection area and at the top of the internal pipe, wherein the screen assembly includes a plurality of spaced screen elements with openings sized to collect solid particles from fluid flowing in the fluid flow path, wherein each screen element has openings progressively smaller in the direction of the fluid flow path.