A grooved drain cap is used as a system drain on the end of a pipe run. When creating a vertical drain, either a concentric or eccentric drain cap may be used. For a horizontal application the typical drain cap style is eccentric. A drain cap may also be used as a reducer to extend the system line to a single sprinkler head or other reduced pipe size where the connecting pipe has a male thread. A standard drain cap has a 1″ female threaded outlet, but other sizes are available. The smaller 1/4″ size can be a convenient system pressure gauge point.
Concentric Drain Cap