LPG & LNG Transfer Pumps
AxFlow supplies LPG and LNG transfer pumps for the safe and reliable handling of volatile liquefied gases across storage terminals, tank farms, loading and unloading systems, marine installations and industrial processes.
Our range includes canned motor, magnetic drive, submerged in-tank, side channel, regenerative turbine and rotary vane pumps, allowing the pump technology to be selected around the liquid, temperature, flow, pressure and available NPSH of the application.
From LPG tanker unloading and cylinder filling to demanding cryogenic in-tank duties, AxFlow can engineer pump solutions for applications where high vapour pressure, low viscosity, low NPSH and fluid containment are critical.
What is an LPG or LNG transfer pump?
An LPG or LNG transfer pump is designed to move liquefied gas while maintaining the pressure and temperature conditions required to keep the product in its liquid phase.
This is more demanding than pumping conventional hydrocarbons. Liquefied gases can operate close to their vapour pressure, so relatively small pressure losses at the pump inlet can cause vaporisation, loss of performance and cavitation.
LPG and LNG also require different pump considerations.
LPG (Liquefied Petroleum Gas) generally consists primarily of propane, butane or mixtures of the two and is commonly stored as a liquid under pressure.
LNG (Liquefied Natural Gas) consists predominantly of methane and is stored at cryogenic temperatures of approximately −162°C at atmospheric pressure. LNG pumps therefore require materials and pump designs specifically engineered for cryogenic service.
For this reason, an LPG pump should not automatically be assumed to be suitable for LNG.
Challenges When Pumping LPG and LNG
Low NPSH and high vapour pressure
LPG and LNG are frequently pumped close to their boiling point. If the pressure at the pump inlet falls below the liquid's vapour pressure, part of the liquid can vaporise.
This can result in:
- cavitation and unstable operation
- reduced pump capacity
- increased vibration
- loss of discharge pressure
- damage to hydraulic components
- difficulty emptying storage tanks to low liquid levels
Pump selection must therefore consider NPSHa, NPSHr/NPSH3, vapour pressure, suction losses and tank operating pressure, rather than flow and differential pressure alone.
Low viscosity and lubricity
Liquefied gases are thin liquids and may provide relatively poor lubrication compared with conventional oils and hydrocarbons. Bearing design, internal clearances and pump technology therefore become important considerations.
Cryogenic temperatures
For LNG service, the pump and its materials must tolerate extreme low temperatures. LNG is normally maintained at approximately −162°C, making it fundamentally different from most pressurised LPG transfer duties.
Fluid containment
Propane, butane, LNG and other liquefied hydrocarbons are flammable. Preventing uncontrolled releases is therefore an important part of pump selection.
Where the application requires enhanced containment, canned motor and magnetic drive pumps eliminate the conventional rotating mechanical shaft seal, removing a potential leakage point.
LPG & LNG Pump Applications
AxFlow can support liquefied-gas pumping applications across LPG storage depots, LNG terminals, tank farms, petrochemical plants, refineries, marine installations and industrial gas facilities.
Typical duties include bulk tank transfer, storage-tank unloading, road-tanker and rail-tanker loading or unloading, LPG bottle filling, plant-to-plant transfer, process circulation, marine fuel transfer and bunkering, high-pressure boosting and cryogenic in-tank pumping.
For LPG installations where recovering the remaining liquid and vapour from tanks or tankers is required, AxFlow can also provide vapour recovery systems using specialist liquefied-gas compressor technology.
Which Pump Type Is Best for LPG and LNG?
There is no single pump technology that is ideal for every liquefied-gas application.
| Application | Typical pump technology | Key advantage |
|---|---|---|
| LPG tanker loading/unloading | Rotary vane | Strong priming and efficient LPG transfer |
| LPG cylinder/bottle filling | Rotary vane | Consistent transfer and compact installation |
| Low-flow, high-head LPG | Side channel / regenerative turbine | High head from relatively low flows |
| LPG with vapour present | Side channel / turbine | Better tolerance of partially gaseous inlet conditions |
| Hazardous LPG process transfer | Canned motor / magnetic drive | No conventional mechanical shaft seal |
| High-head liquefied gas | Multistage canned motor | High differential head with sealless containment |
| API process duties | API 685 canned or magnetic drive | High-integrity sealless process pumping |
| LNG storage tanks | Cryogenic submerged/in-tank | Flooded suction and reduced NPSH problems |
| LNG marine or terminal transfer | Cryogenic pump selected for the exact duty | Materials and hydraulics engineered for LNG temperature |
Why Choose AxFlow for LPG & LNG Pumps?
AxFlow combines multiple pump technologies rather than trying to apply one design to every liquefied-gas duty.
Our portfolio includes rotary vane, side channel, regenerative turbine, magnetic drive, canned motor and submerged in-tank pump technologies, allowing the equipment to be selected around the actual process conditions.
AxFlow UK has more than 30 years' experience with cryogenic pump applications, while its long-standing HERMETIC relationship provides access to specialist canned motor technology for demanding containment and liquefied-gas duties.
Need help selecting an LPG or LNG pump?
Send us your liquid, temperature, flow, required pressure/head, tank pressure and available NPSH, and our engineers can recommend the most suitable pump technology for your application.
