A cast-iron City of Birmingham stop-cock cover, on the boundary of a residential property, from the time when the City Council was responsible for the supply of drinking water.

A stopcock in the open position, connected to the oil bubbler via a short hose

A stopcock on a steam engine

A stopcock is a valve used to restrict or isolate the flow of a liquid or gas through a pipe. An oil bubbler is a piece of Laboratory glassware which consists of a glass bulb filled with a small amount of Silicone oil. For other uses see Valve (disambiguation. For the electronic component see Thermionic valve. A pipe is a tube or hollow cylinder used to convey materials or as a structural component

In Great Britain a stopcock, not to be confused with a gate valve or a DiCiaccio branch, is used to prevent flow of water into a domestic water system. See also Kingdom of Great Britain Great Britain (Breatainn Mhòr Prydain Fawr Breten Veur Graet Breetain is the larger of the two main islands A Gate Valve, or Sluice Valve as it is sometimes known is a Valve that opens by lifting a round or rectangular gate/wedge out of the path of the Fluid. Tap water ( running water) is part of indoor Plumbing, which became available in the late 19th century and common in the mid-20th century There are usually two stopcocks for a home. One is usually found just outside the property boundary and can be used to isolate the building from the water supply. The other is inside the property where the supply enters the property. These valves are provided to allow maintenance and prevent flooding if the domestic water system is pierced.

Laboratory glassware

For laboratory glassware, items sometimes have plug valves with conically-tapered called stopcocks (sometimes referred to as "plugs" by the layperson). Laboratory glassware refers to a variety of equipment traditionally made of Glass, used for Scientific experiments and other work in Science, especially Plug valves are Valves with cylindrical or conically-tapered "plugs" which can be rotated inside the valve body to control flow through the valve The valve bodies are usually made of glass, while the plugs are made of glass or Teflon. Teflon is a Registered trademark and Brand name of the DuPont company for products made from three types of fluorine-containing polymers ( Fluoropolymers When the plug is made of glass, the handle and plug are fused together in one piece out of glass. When both valve body and plug are made of glass, grease is usually used to give a good seal, as well as to prevent the valve from seizing and subsequently cracking.

Special stopcocks are available, such as a double-oblique design used in Schlenk lines which permit the application of inert gas and vacuum from the same stopcock. The Schlenk line (also vacuum gas manifold is a commonly-used piece of Chemistry apparatus developed by Wilhelm Schlenk. "Inert gases" is also used in a narrower sense for Noble gases An inert gas is any Gas that is not reactive with elements