A sphere with a through-port sits between two seats, usually PTFE or another polymer, and a 90 degree turn of the stem lines the port up with the pipe or turns it crosswise. Full-port versions match the pipe bore, while reduced-port (standard-port) versions step down one size to save cost and weight. Soft-seated ball valves give drip-tight shutoff and fast operation, which is why they dominate small isolation duty.
Swap that gate for a 2 inch full-port ball valve so operators can see from the handle whether it's open.
Handle in line with the pipe means open; handle across the pipe means shut. Rookies who forget this get laughed at once.
Also heard as
- quarter-turn ball
Related terms
Floating ball valve
A ball valve whose ball is held only by the seats and is pushed downstream by line pressure to make the seal.
Trunnion-mounted ball valve
A ball valve whose ball is anchored top and bottom on trunnions while spring-loaded seats press against it.
Bubble-tight
Shut off with no visible seat leakage when tested with air or gas under water.
Fire-safe
Describes a valve built to limit leakage through and around it during and after an external fire.
Plug valve
A quarter-turn valve that rotates a tapered or cylindrical plug with a port through it to start or stop flow.