Pump for very cold liquids

Pumping apparatus for very cold liquids comprising:

• a thermally insulated and pressure-tight sealed vessel having a thermally insulated neck (8) and equipped with an inlet and an outlet respectively for introduction and removal of a very cold liquid;
• an immersion-type rotary pump (13) mounted on suspension means through said neck of said vessel for operation when immersed in very cold liquid in said vessel, and connected directly to one of said inlet and outlet and to the interior of said vessel;
• a drive-shaft (19) for said rotary pump passing through said vessel neck and through said suspension means for said pump;
• bearings (20,21) for said drive-shaft held by said suspension means;
• thermal insulation means interposed in said drive shaft and in said pump suspension means for opposing heat flow down the neck of said pump, including an insulation (23) on the pump side of said bearings (20,21) and
• means for pressure-tight sealing of said neck (8) of said vessel. in the form of a seal cap (29) covering the end portion of said drive shaft (19) remote from said pump;
• a permanent magnet coupling (20) for transfer of torque to said drive shaft (19) through said cap (29), connected above said cap to a motor shaft coaxial with said drive shaft;
• a motor (25) outside said vessel for driving said motor shaft and thereby said drive shaft.