Abstract: A seal-less, magnetic drive pump for pumping fluids at very low temperatures below about −100 degrees centigrade such as liquid nitrogen and at cryogenic temperatures below about −150 degrees centigrade such as liquefied natural gas (LNG). The pump includes a housing having an intake and exhaust with a back plate mounted therein in which a shaft is journaled in self-lubricating ball bearings having metallic balls and races and having polymeric ball retainers. An impeller is mounted on the first end and a first magnet is mounted on the second end of the shaft. A second magnet is positioned so as to rotate around the first magnet to rotate the impeller. The first magnet is encased in a material having a coefficient of thermal expansion greater than that of the magnetic material.

Abstract: A seal-less, magnetic drive pump for pumping fluids at very low temperatures such as liquid nitrogen and liquefied natural gas (LNG). The pump includes a housing having an intake and exhaust with a back plate mounted therein in which a shaft is journaled. An impeller is mounted on the first end and a first magnet is mounted on the second end of the shaft. A second magnet is positioned so as to rotate around the first magnet to rotate the impeller. The first magnet is encased in a material having a coefficient of thermal expansion greater than that of the magnetic material.