GB1409461A - Close clearance viscous fluid seal system - Google Patents

Abstract

1409461 Pump plunger seals UNION CARBIDE CORP 6 April 1973 16638/73 Heading F2B The plunger 104, Fig. 1, of a high pressure pump 101 is sealed by means comprising circulating sealing liquid under pressure to an annular clearance seal zone 110 surrounding the plunger, the zone being sealingly separated from the pumped liquid chamber 103 by a floating piston whereby the sealing liquid is subjected to the pressure of the pumped liquid in the chamber 103. The piston is sealed in a chamber in the pump body 102 by seals 108 and 109 and divides the chamber into two parts 106a and 106b communicating respectively with the pump chamber 103 and via the seal zone 110 with a leakage chamber 111 sealed by seals 112 and connected by a conduit 113 with a sealing liquid reservoir 114. A pump 115 pumps liquid from the reservoir to the zone 110 at a constant pressure controlled by a regulator 119 to be slightly above the minimum pressure of the liquid in the chamber 103 during the suction stroke. In operation, during the compression stroke the pressure of the pumped liquid moves the piston 107 to the left to impose the same pressure on the sealing liquid in the chamber part 106b and in the zone 110, and during the suction stroke, the piston is returned to the right by the pressure of sealing liquid supplied by the pump 115. A vent passage 120 and valve 121 may be fitted. In a modification, Fig. 2 (not shown), the piston (207) is located in a bore in the pump body (202) and the seal chamber parts (206a and 206b) communicate with the pump chamber (203) and seal zone (214) through passages (205, 213) in the body. In a further modification, Fig. 3 (not shown), sealing liquid is supplied to the seal zone (320) through a passage (316) and a spring-loaded valve (315) in the plunger (304). In the embodiment shown in Fig. 4, the seal zone 416 is separated from the pump chamber 403 by a seal ring 419 and the floating piston 407 is housed in a chamber 406 external to the pump body 402 and connected to the chamber 403 and zone 416 by conduits 405 and 414, 417 respectively.