Abstract: Disclosed is an improved pressure differential circulating valve which can be connected to and form a portion of the tubing string disposed in casing for flow of fluid from a formation traversed by the casing and the tubing or for other uses in well bores which has the following improvements: the valve seat is detachable from the main valve body and a seal arrangement is provided so that the valve seat is movable longitudinally and transversely of the body effective to align the valve seat with the valve sleeve seating surface to form a complete 360 degree seat; the detachable valve seat permits the use of different metal alloys or other materials on the main valve seating surface to withstand various conditions of use; the throat area has been opened which increases the hydraulic lifting forces of the valve sleeve thereby permitting lower treating pressures; and a manifold area is provided which uniformly distributes fluid from the ports in the body causing the downhole differential circulating valve to snap

Abstract: Disclosed is a pressure differential circulating valve which can be connected to and form a portion of the tubing string disposed in casing for flow of fluid from a formation traversed by the casing and the tubing. Advantageously, the pressure differential circulating valve has an unrestricted passageway of substantially the same size and shape as that of the tubing string, yet is small enough in external diameter to be disposed in normal casing set in a well bore, can be set to open at any flow pressure and can be placed at any depth. Thus, in pumping fluids down the tubing, such as hot oil to remove paraffin from the inside of the tubing and pump rods and the like, or other treating fluids, such as to treat corrosion problems, the pressure differential circulating valve opens at the predetermined pressure permitting flow of fluid therethrough into the annulus between the casing and the tubing string.