Virginia Chemicals Inc.

John P Clarke

Ernest W Schumacher

A method is described for manufacturing, shipping, and handling a process component of heat-exchanging, air-conditioning, and refrigerating circuits, such as a filter drier or an accumulator, so that the process component can be joined to fluid tubing of such circuits by field brazing, using phosphorus-bearing copper filler metal with little or no silver content to make the braze joints. The method finally comprises the steps of selecting the tubing used for the connectors with a diameter which is smaller than the diameter needed for the field brazing to the circuit tubing and then mechanically expanding the other end of the tubing from 2% to 20% to this field brazing diameter, whereby the tubing is work-hardened to a hardness of 45-50 F Scale Rockwell and is able to withstand damage from shipping and handling operations and thereby returns the critical tolerances needed by the field brazing. However, mechanical expansion is restricted to a maximum of 6% if it is desired to avoid an orange peel surface on the connector. Mechanical expansion is done by punching in one to four steps, each punch increasing the diameter of the tubing by 0.005 to 0.010 inch.

Rehardening of copper connectors

A combined filter and filter-drier, for the suction side of refrigeration and air conditioning systems, comprises a dual filter system straddling a cylindrical plug of dessicant. Upstream of the dessicant, a rigidly built primary filter assembly comprises an inlet deflector and a stepped filter. Downstream of the dessicant, a secondary filter assembly comprises an outlet filter pad which is compressed by a coaxially disposed spring near the inlet of the filter/filter-drier. The inlet deflector is preferably triangular in shape and is disposed transversely to the inlet. The stepped filter comprises a deflector filter pad, which preferably has the same shape but a smaller size than the inlet deflector, and a filter pad which is round, preferably is twice as thick as the deflector filter pad, and has a smaller diameter than the inside diameter of the filter/filter-drier, whereby an annular space is provided for swirling flow of an incoming vaporous mixture which thereby enters the peripheries of the stepped filter. In consequence, particles are gradually deposited throughout the interiors of the deflector filter pad and inlet filter pad so that pressure build up across the filter/filter-drier is also gradual and provides a warning of impending need for replacement. A method for constructing the filter-drier is also disclosed.

Growing community of inventors

DeSoto, TX, United States of America

John P Clarke