Plumbing valve is a mechanical in-line device used to open or shut off the flow of water, gas or oil. Valves come in a variety of types and sizes and can be used for emergency shut-off, maintenance, backflow prevention, drainage, utility and other applications.
Most plumbing valves are made from brass or bronze and, if used for potable water applications, must be lead-free compliant.
Majority of valves can be categorized into 1/4-turn and multi-turn types. 1/4-turn valves can be opened or closed by turning the handle 90 degrees, whereas multi-turn valves would require turning the handle several times.
Plumbing valves come in a multitude connection options, including threaded, sweat (solder), compression, press, push-to-connect and PEX. Connections sizes vary by valve type and can be as small as 1/8" or as large as 2".
Depending on the end application, a valve may or may not require a special certification or approval. Gas ball valves, for example, must have a CSA approval, while outlet stop valves must be lead-free compliant, since they come in direct contact with drinking water.
Unlike valves used for heating, plumbing valves are generally not categorized as normally open or normally closed, since most of them are manually operated. Check valves, however, are always closed, while y-strainers are always open.