Used Cryogenic Pumps for Sale

It moves liquefied gas (nitrogen, oxygen, argon, CO2, LNG) out of a tank to transfer it or push it to a higher delivery pressure. The liquid must stay above its boiling pressure the whole way through. If it doesn't, it turns to vapor inside the pump (cavitation) and the pump stops delivering. Centrifugal, submerged and reciprocating designs each cover different ranges of flow and pressure.

Sources: AIGA 089/14 · Cryostar HP pumps · Nikkiso centrifugal pumps

A reciprocating (piston) pump gives nearly steady flow across a wide pressure range, which suits high-pressure, lower-volume work like cylinder filling, with ratings in the hundreds of bar. A centrifugal pump moves much more volume, but its pressure falls as flow rises, so it suits transfer, tank filling and truck loading.

Sources: Pumps & Systems · Cryostar HP pumps · Cryostar submerged pumps

In a submerged pump, the motor and pump sit together inside the liquid, in a sealed vessel or the tank itself. That eliminates the shaft seals an external-motor pump needs. They're multistage centrifugal pumps used for LNG fueling, microbulk delivery, truck loading and storage transfer.

Sources: Nikkiso submerged pumps · Cryostar submerged pumps

It depends on the manufacturer and the pump model, so contact the manufacturer before changing service. In general, oxygen service requires every wetted part cleaned for oxygen and verified, and the pump built so leaking oxygen can't reach a hydrocarbon lubricant. Pumps built for LNG stay in LNG service.

Sources: AIGA 089/14 · EIGA Doc 159 · CGA G-4.1

Start with the cold end and its seals; cold liquid leaking past worn gland seals has made warm-end parts brittle enough to fail. Listen for abnormal noise or vibration, which can mean damaged bearings or cavitation, and look for pitting on a centrifugal pump's impeller. Check the vacuum jacket on the cold end if it has one, and ask how the pump was stored, since idle equipment picks up moisture and corrosion.

Sources: AIGA 089/14 · EIGA Doc 159 · Wilo — cavitation · Machinery Lubrication — equipment storage

Ask for the make, model and serial; the product it pumped; the running hours; and the maintenance and repair log. Guidance calls for a dated repair record, because it shows chronic problems. Ask why it came out of service and whether it was ever in oxygen service, since oxygen parts need special cleaning and handling. Seal condition is judged against running hours.

Sources: EIGA Doc 148 · AIGA 089/14 · EIGA Doc 159

Look for flow or pressure below normal, leaking piston gland seals, or a noisy pump. First rule out supply problems: valve positions, tank level and blocked filters. After that, low output can mean damaged, stuck or leaking suction or discharge valves. Seal leaks are checked against seal wear and running hours.

Sources: EIGA Doc 159 · AIGA 089/14

NPSH is the margin between the pressure of the liquid reaching the pump and its boiling pressure; sub-cooling creates that margin. Too little causes cavitation and loss of prime. Guidance calls for short, continuously sloped suction lines with no low points or long horizontal runs, insulation to cut heat leak, and a written minimum sub-cooling and tank pressure before startup.

Sources: AIGA 089/14 · EIGA Doc 159 · EIGA Doc 148

The whole cold end must be cold before it runs. Starting warm wears the plastic piston rings and risks overheating. Guidance calls for a temperature check on the suction return, interlocked so the pump can't start until it's cold, plus a loss-of-prime shutdown on every pump.

Sources: AIGA 089/14 · EIGA Doc 159