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A full understanding of solenoid valves and some selection and installation tips will help to avoid trouble and provide an optimum application.
SOLENOID CONSTRUCTION
There are two types of solenoid valve construction: hermetic and take-apart.
Hermetic valves are brazed or welded together at the factory and have the advantage of being inherently free of external leaks. Hermetic construction is most common in valves having a port size of 1/2 in. or less. Hermetic valves, of course, cannot be disassembled for cleaning or repair.
Take-apart types can be serviced and repair kits are normally available from the manufacturer. Some form of seal, usually elastomer gaskets or 0rings, is required.
This produces the potential for leakage after a period of service, particularly when prolonged high temperatures are encountered. The variety of refrigerants and lubricants now used results in a difficult application for seal materials. Also, formulas published by O-ring manufacturers indicate that permeability directly through the seal material can account for as much as 0.25 oz/year of refrigerant loss in a medium- to large-size valve.
PILOTED OR DIRECTLY OPERATED
Valves with...