PUMP APPARATUS FOR VERY COLD LIQUIDS

摘要

A pump for cryogenic liquids is provided with an enclosing vessel of the construction of a Dewar flask. A submerged multistage rotary pump is suspended from the mouth of the flask by means of a system providing thermal insulation opposing the flow of heat down the neck of the flask. The drive motor is coupled to the drive shaft of the immersion pump through a magnet coupling of which the elements are separated by a pressure seal. The latter and the extensive thermal insulation make the pump suitable for pumping liquid air or liquid nitrogen in a pressurized closed circuit and the presence of a supply of the cryogenic liquid around the pump itself makes it possible to start the pump at once after a quiescent period. A level-control sonde operates to assure that the presence of the necessary minimum of liquid in the vessel.