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2. Backflow prevention device - Wikipedia

   en.wikipedia.org/wiki/Backflow_prevention_device

   [example needed] A typical backflow assembly has test cocks and shut-off valves, and must be tested when installed, if relocated or repaired, and also on a periodic basis. [citation needed] In the US, the Environmental Protection Agency (EPA) holds local water suppliers responsible for maintaining a certain amount of purity in potable water ...

3. Shutdown valve - Wikipedia

   en.wikipedia.org/wiki/Shutdown_valve

   A shutdown valve (also referred to as SDV or emergency shutdown valve, ESV, ESD, or ESDV; or safety shutoff valve) is an actuated valve designed to stop the flow of a hazardous fluid upon the detection of a dangerous event. This provides protection against possible harm to people, equipment or the environment.

4. List of valves - Wikipedia

   en.wikipedia.org/wiki/List_of_valves

   Valves can be categorized into the following types, based on their operating mechanism: Ball valve, for on–off control without pressure drop. Ideal for quick shut-off, since a 90° turn completely shuts off, compared to multiple 360° turns for other manual valves; Butterfly valve, for on–off flow control in large diameter pipes

5. Reduced pressure zone device - Wikipedia

   en.wikipedia.org/wiki/Reduced_pressure_zone_device

   A reduced pressure zone device (RPZD, RPZ, or RPZ valve) is a type of backflow prevention device used to protect water supplies from contamination. RPZDs may also be known as reduced pressure principle (RP), reduced pressure principle backflow prevention devices , [ 1 ] [ 2 ] reduced pressure zone assemblies (RPZA), [ 3 ] or reduced pressure ...

6. Atmospheric vacuum breaker - Wikipedia

   en.wikipedia.org/wiki/Atmospheric_vacuum_breaker

   It is usually constructed of brass and resembles a 90-degree elbow with a hood on its top to allow air to enter the water system if a siphon attempts to form. Inside this elbow is a poppet valve that is held "up" by the water pressure found in the system, closing the air entrance to the device. If the pressure in the "upstream side" is reduced ...

7. Isolation valve - Wikipedia

   en.wikipedia.org/wiki/Isolation_valve

   Isolation valves must effectively stop the passage of fluids. [4] Gate valves, ball valves and plug valves are generally considered to provide tight and effective shut-off. Globe valves and Butterfly valves may not be tight shut-off due to wear on the plug or the seat, or due to their design, and may not be appropriate to provide effective ...