A pump for pumping a cryogenic liquid includes a pump housing having a cylinder with a piston slidably positioned therein. An intermediate fluid chamber that receives an intermediate fluid is defined within the cylinder adjacent to a first end of the piston and a fluid pumping chamber is defined within the cylinder adjacent to a second end of the piston. An intermediate fluid seal is attached to the piston and engages the cylinder. A pumped fluid seal attached to the piston and configured to engage the cylinder, said pumped fluid seal spaced from the intermediate fluid seal so that a differential pressure space is defined within the cylinder between the intermediate fluid and pumped fluid seals. A differential pressure vent valve is in fluid communication with the differential pressure space. A differential pressure switch senses a pressure within the differential pressure space and opens the differential pressure vent valve when the pressure within the differential pressure space reaches a predetermined pressure level.

A pump for pumping a cryogenic liquid includes a pump housing having a cylinder with a piston slidably positioned therein. An intermediate fluid chamber that receives an intermediate fluid is defined within the cylinder adjacent to a first end of the piston and a fluid pumping chamber is defined within the cylinder adjacent to a second end of the piston. An intermediate fluid seal is attached to the piston and engages the cylinder. A pumped fluid seal attached to the piston and configured to engage the cylinder, said pumped fluid seal spaced from the intermediate fluid seal so that a differential pressure space is defined within the cylinder between the intermediate fluid and pumped fluid seals. A differential pressure vent valve is in fluid communication with the differential pressure space. A differential pressure switch senses a pressure within the differential pressure space and opens the differential pressure vent valve when the pressure within the differential pressure space reaches a predetermined pressure level.

The invention relates to a fluid compression apparatus comprising a housing having a compression chamber, an intake system communicating with the compression chamber which is configured to allow fluid to be compressed into said compression chamber, and a mobile piston for ensuring the compression of the fluid in the compression chamber. The apparatus further comprises a discharge port which is configured to allow the exit of compressed fluid from the compression chamber, the compression chamber being defined by a portion of the body of the piston and a fixed wall of the apparatus, the piston being translationally mobile along a longitudinal direction. The invention is characterized in that the piston has a tubular portion mounted around a fixed central guide, a first terminal end of the central guide forming the fixed wall delimiting a part of the compression chamber. The apparatus also comprises a sealing system formed between the central guide and the piston according to the longitudinal direction of translation of the piston, the intake system being located at a first end of the apparatus, the discharge port being located at a second end of the apparatus.

Apparatus, consisting of a probe, containing a lumen and having a distal end configured to contact tissue of a living subject. A temperature sensor is located at the distal end, and a pump, having a pump motor, is coupled to deliver a cryogenic fluid through the lumen to the distal end of the probe and to receive the cryogenic fluid returning from the probe. There is a separator, coupled to separate the returning cryogenic fluid into a returning cryogenic liquid and a returning cryogenic gas, and a flow meter, coupled to measure a rate of flow of the returning cryogenic gas. A processor is configured to control a rate of pumping of the pump motor in response to a temperature measured by the temperature sensor and the rate of flow of the returning cryogenic gas.

The invention relates to a fluid-compression device including a compression chamber comprising a movable piston, the device comprising a first end housing a first end of the compression chamber, the device comprising a second end housing a second end of the compression chamber, the piston being translatable between the first and second ends of the compression chamber, the device comprising a regeneration pipe connecting the first and second ends of the compression chamber and including a regenerator, the device comprising a supply pipe comprising an upstream end intended to be connected to a source of fluid to be compressed and a downstream end opening into the first end of the compression chamber, the supply pipe comprising a valve assembly, the device comprising a pipe for discharging the compressed fluid comprising an upstream end connected to the compression chamber and a downstream end intended to be connected to a receiver of the compressed fluid, the discharge pipe comprising a valve assembly, characterized in that the upstream end of the supply pipe is connected directly to the first end of the compression chamber, i.e. without passing through a pre-compression chamber in the first end of the device.

The invention relates to a fluid-compression device including a compression chamber comprising a movable piston, the device comprising a first end housing a first end of the compression chamber, the device comprising a second end housing a second end of the compression chamber, the piston being translatable between the first and second ends of the compression chamber, the device comprising a regeneration pipe connecting the first and second ends of the compression chamber and including a regenerator, the device comprising a supply pipe comprising an upstream end intended to be connected to a source of fluid to be compressed and a downstream end opening into the first end of the compression chamber, the supply pipe comprising a valve assembly, the device comprising a pipe for discharging the compressed fluid comprising an upstream end connected to the compression chamber and a downstream end intended to be connected to a receiver of the compressed fluid, the discharge pipe comprising a valve assembly, characterized in that the upstream end of the supply pipe is connected directly to the first end of the compression chamber, i.e. without passing through a pre-compression chamber in the first end of the device.

An improved filter apparatus for a cryogenic fluid includes a filter and a support. The filter includes a mesh having an internal space and an open end. The support is associated with the mesh for maintaining a volume of the internal space above a predetermined value. In operation cryogenic fluid enters the internal space through the mesh and exits the open end thereof.

An improved filter apparatus for a cryogenic fluid includes a filter and a support. The filter includes a mesh having an internal space and an open end. The support is associated with the mesh for maintaining a volume of the internal space above a predetermined value. In operation cryogenic fluid enters the internal space through the mesh and exits the open end thereof.

A flange for a pump comprises first and second faces and a passageway for cryogenic fluid flow extending from the first face to the second face and at least one of (1) the passageway is for a pipe and comprises a first portion of a first diameter and a second portion of a second diameter greater than the first diameter, wherein when the pipe has an outer diameter that is smaller than the second diameter a gap is formed between the pipe and the passageway where the pipe passes through the second portion; and (2) a first annular groove in one of the first face and the second face and extending around the passageway, wherein the first annular groove in cooperation with the passageway forms a bellows. The gap and bellows increase the thermal resistance between the passageway and the flange, and the bellows allows for flexure during thermal contractions of the flange reducing thermal stress on welded fluid seals.

A flange for a pump comprises first and second faces and a passageway for cryogenic fluid flow extending from the first face to the second face and at least one of (1) the passageway is for a pipe and comprises a first portion of a first diameter and a second portion of a second diameter greater than the first diameter, wherein when the pipe has an outer diameter that is smaller than the second diameter a gap is formed between the pipe and the passageway where the pipe passes through the second portion; and (2) a first annular groove in one of the first face and the second face and extending around the passageway, wherein the first annular groove in cooperation with the passageway forms a bellows. The gap and bellows increase the thermal resistance between the passageway and the flange, and the bellows allows for flexure during thermal contractions of the flange reducing thermal stress on welded fluid seals.