The S4AD is based on the same valve body, principles, and length dimension as the standard S4A valves making for easy field replacements. This heavy duty solenoid valve is suitable for ammonia, R-22, other refrigerants,andcertainoilsandotherfluidsapproved for use in refrigeration. The S4AD is a pilot operated, dual-position, normally closed valve. aIt will close on power failure. The S4AD may be opened by means of the manual opening stem for servicing or in case of electrical power failure. The Type S4AD Solenoid Valve is furnished with FPT InternalNPT(U.S.StandardTaperPipeThread),Socket Weld, Weld Neck orODS (solders over copper tubing of given diameter) connections. The valve may be easily removed from between the flanges for servicing. It is advisable to install as strainer upstream of each valve to prevent entrance of foreign material into the valve and the rest of the system. Refrigerating Specialties strainers are available to close-couple to valve inlets