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Cryogenic Liquid Pump Failure And Handling

Jun 10, 2018

1 Difficult to drain or not to drain completely
(1) The suction pressure provided in the suction pipe is insufficient. It  is possible to increase the suction pressure, increase the liquid  level, increase the inner diameter of the suction line if necessary, and  shorten the length of the suction line.
(2) Insufficient insulation and cooling, a large amount of heat intrusion, so that the liquid temperature rises and vaporizes. To  improve the insulation performance of the insulation layer, it is  generally preferable to use anhydrous insulation outside the insulation  layer.
(3) There is a gas blocking phenomenon. Check the inlet pipe and add an exhaust pipe to make the exhaust air unobstructed.
(4) The inlet and outlet valves are stuck. If  it is due to wet icing, it needs to be heated to blow dry and then  start; if it is an impurity, it will be removed after removal and drying  and restart.
(5) The return air line is closed. Open the return air line.
(6) The liquid is too close to the vapor phase. Open the tank vent valve and let go of some of the gas.
(7)  The inlet valve did not emit a slight working impact sound, the motor  load was significantly reduced, the pump could not normally enter the  liquid, and there was gas in the cylinder liner. Exhaust measures should be taken; cooling may not be sufficient and cooling may be performed again.
(8)  Damage to the sealing surface of the inlet and outlet valves, spring  breakage, and foreign matter attached to the sealing surface. Remove and repair damaged parts and correct the seal.
(9) Piston ring wear. This is a gradual process that does not happen suddenly. Replace the piston ring.
5.2 Pressure instability or pressure
(1) The liquid damper has insufficient capacity or insufficient gas phase volume. Select the appropriate liquid damper. The upper part of the damper should not have insulation material, and the upper part should be gas-phase space.
(2) Gas exists in the pump head. Take exhaust measures and check the pressure gauge; check if the vacuum jacket loses vacuum.
(3) Sealer leakage. The sealer has severe frost and prevents normal operation. The  specific pressure of the seal should be adjusted again; if there is any  foreign matter, ice will enter the sealing part; if the seal is worn  out. For the cause of the fault, replace the parts and dry them.