GB884537A - Check valve - Google Patents

Abstract

884,537. Valves. CHATLIFF VALVE & MANUFACTURING CO. Sept. 29, 1959 [Jan. 29, 1959], No. 33007/59. Class 135. A check valve has a plunger 7 carrying a gasket 8 for co-operation with a seat 4 surrounding the inlet 3 and a connection by way of grooves 9, 10 between the outlet or outlets 5 and a chamber at the end of the plunger remote from the inlet. The valve opens rapidly due to the momentum acquired by the plug before the lower part 7 below the groove 10 permits communication between the inlet and outlet, and also due to the tendency for fluid flowing through the outlet to reduce the pressure in the groove 10 and to the impact force acting on the plug due to the change of direction of the escaping fluid. The plunger is arrested by fluid trapped when the groove 10 has moved beyond the upper limit of the outlet. When reverse flow commences the static pressure on the lower face of the plunger is reduced causing the pressure behind the plunger to initiate closure whereupon the groove 10 is brought into communication with the outlet so that outlet pressure has access to the space behind the plunger to complete the closure. In modifications the end of the plunger that coacts with the seat may be conical, or closure may be effected by engagement of the cylindrical part of the plunger with an 0-ring in a groove in the housing, and the groove 9 may be helical or interrupted by an additional circumferential groove in which case the two parts of the groove 9 may be of different cross-section to give two different rates of leakage from the space behind the plunger and consequently a variable rate of movement of the plunger. The passage between the outlet and the upper side of the plunger may alternatively be formed by a clearance between the upper part of the plunger, which may have flats, and the bore, or by a porous upper portion of the plunger. Further modifications, in one of which the plunger is spring loaded, are described in which the passage is constituted by a radial bore or bores in the plunger opening to an axial recess open at the upper end.