a refrigerant recovery system including an interface connection to an existing refrigeration system high pressure relief valve , a check valve , a refrigerant recovery tank , and an interconnecting conduit . a schrader type valve is affixed to the recovery tank thereby permitting service extraction of refrigerant trapped therein . two pressure sensing switches are provided in the refrigerant recovery tank wherein a first switch has normally open contacts and is used to signal an overpressure event , and a second switch has normally closed contacts and terminates operation of the refrigeration system upon sensing an overpressure event .