GB526242A - Improvements in unloading valves for reciprocating ram pumps - Google Patents

Abstract

526,242. Regulating delivery of pumps. TOWLER, J. M., and TOWLER, F. H. March 6, 1939, No. 7219. [Class 102 (i)] [Also in Group XXIX] A relief device for a reciprocating ram pump comprises a piston valve which is movable relative to a discharge outlet in the wall of each pump bore to byepass some or all of the liquid in one or more pump bores either progressively as the delivery pressure increases or immediately it attains a predetermined pressure. Fig. 1 shows the device applied to a three-ram pump having discharge valves 25 leading to a common discharge pipe 8. The unloading valve comprises a tubular piston valve 13 having an axial bore 14 discharging at one end into the sump and radial ports 18 leading to two peripheral grooves 15, 16. The control edges of these grooves may be chamfered to give a gradual opening. The discharge pressure acts on a ram 26 connected to the valve and as the pressure rises it moves the valve against the action of an adjustable loading spring 20, first bringing the groove 15 opposite the port 9 to unload the first cylinder, further movement unloads the second cylinder and still further movement brings the tapered end 17 opposite the port 11 and partly unloads the third cylinder. In a modification this tapered end is replaced by a third peripheral groove and the valve member is extended into the control chamber to replace the plunger 26. The endwise movement of the valve is limited by a collar 28 on the plunger 26. The rams may be unloaded in any desired order, either together or one or more at a time. In a modification the movement of the valve is under the control of a loose-ball auxiliary valve opened against the action of a spring by discharge conduit pressure. Specification 392,992 is referred to.