Liquid Gas Pumps Liquid Gas Pumps are typically centrifugal pumps used to pump liquefied hydrocarbons such as propane, butane, propylene and ethylene. These liquefied hydrocarbons are pumped at -104�°C, and liquefied natural gas (LNG) (usually methane) is pumped at -161�°C, where they remain liquid because above this temperature the gas begins to boil and evaporate. SUNCENTER Liquid Gas Pumps are air driven at a drive air pressure of 2 to 10bar (29 to145 psi) by the normal air compressor. Basically the principle of operation is similar to a reciprocating amplifier where control of the piston at the end position is regulated by a pilot operated 4/2 way valve.