Helix Technology Corporation

David C Planchard

Paul D Lanoue

Michael J Eacobacci

Robert C Pandorf

Anthony M Guerra

When a refrigerator unit is removed, inner surfaces of a refrigeration unit housing extending into a cryogenically cooled system are heated. The method is performed in such a way as to prevent the external atmosphere from coming in contact with the housing inner surfaces, thus avoiding the problem of ice formation within the housing. A heat gun is used in conjunction with an apparatus which fits into the housing and distributes heated gas, such as nitrogen, from the heat gun to different parts of the housing in relative quantities. The inner surfaces are brought to the same temperature in the same time allowing the housing to be cleaned before the refrigeration unit is replaced. The apparatus guiding the heated gas is mounted on the outside of the housing and includes stops on its supports to keep the apparatus from making contact with the inner surfaces of the housing. Spring loaded temperature sensors attach to the apparatus at different points and make contact with the inner end surfaces of the housing, allowing the housing temperature to be monitored during the heating process.

Replacement method and apparatus for a cryogenic refrigeration unit

The present invention discloses a relief valve containing a poppet valve which is designed to eliminate resonant chattering within the relief valve. The poppet valve contains a plurality of holes of sufficient size and number within the truncated portion of the valve to maintain a fluid pressure difference of about zero between the area within the internal cylinder of the poppet valve and the area within the valve housing about the truncated portion of the poppet cavity.

Bypass relief poppet valve

An exhaust port from a cryopump vacuum vessel leads to an exhaust valve. The valve is protected from contamination by a filter standpipe which extends from the exhaust port into the vacuum vessel and which is open at its end opposite to the exhaust port. The standpipe is of porous material which allows the free flow of gas, water, and liquid cryogens therethrough while retaining contaminating debris within the vacuum vessel. The filter conduit is of screen formed into a cylinder. One end is tapered and pressed into the exhaust conduit. The screen cylinder is stopped in the exhaust conduit by a circumferential ridge.

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Shrewsbury, MA, United States of America

David C Planchard