This is an API gravity adapter coupling found on tanker trucks. It is used for bottom loading and unloading of petroleum tankers. It is manufactured to American Petroleum Institute (API) RP-1004 specifications which allows for connections to drop adapters and rack couplers.
This gravity adapter coupling has a 4″ API coupler on one side and a 4″ female NPT threads on the other side. The API coupler side of this coupling includes self-locking handles for a quick and secure connection to the API valve.
This coupling is used with API valves. Also this coupling’s seal is made of a standard Buna-N Gasket.