NEW SERIES OF HIGH-PRESSURE PUMPS FOR CRYOGENIC LIQUIDS.

A description is given of pumps which are being manufactured to deliver 35-600 liter/h of liquid nitrogen, oxygen, or argon supplied discharge pressures of up to 23 and 42 MPa. The pumps are single-line reciprocating pumps with a shaft rotation speed of 3. 3 sec** minus **1, operating with supercooling of the aspirated liquid for 6-8 degree K. The delivery can be adjusted by changing the stroke of the piston in the range 65-130 mm, only when the pump is stopped. Practical tests have shown that the pumps are reliable in operation and that they have favorable hydraulic characteristics. The maximum stroke of the piston of the new pumps is 30 mm; the mean velocity of the piston is not higher than in the case of pumps from serial production. This offers a long duration of the piston rings and the stuffing box collars, made of F4K20 self-lubricating fluoropolymer. Based on the investigation of different schemes for the liquid supply to the inlet and cooling of the cylinder a design of the cylinder group was selected at which the pump operated steadily at minimum supercooling of the entering liquid. The radial supply of the liquid provides a convenient approach to the inlet valve and pressure pulsations at the inlet are reduced (on air fractionation units the liquid must be supplied to the pump through the pipe A while the suction chamber must be purged through the pipe B when oxygen is pumped at pressures up to 23 MPa).