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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.
Bolt Shut-off Nozzle type BHP - pneumatic or hydraulic actuation. A shut-off bolt, positioned perpendicular to the melt channel moves up and down according to actuation, and thus shuts off/opens the melt flow. This nozzle type has a single melt channel. It therefore does not require rerouting of the melt around the shut-off mechanism.
The basic principle behind partial stroke testing is that the valve is moved to a predetermined position in order to determine the performance of the shut down valve. This led to the adaptation of pneumatic positioners used on flow control valve for use in partial stroke testing. These systems are often suitable for use on shutdown valves up to ...
There is a variety of manufacturers of these gauges, but most utilize either a three-valve or a five-valve design to test the RPZD in different ways. In the UK , [ 6 ] Illinois, New York , [ 7 ] Texas , [ 8 ] and Missouri ( RsMO 10c60-11 ), the RPZD valve must be tested at least every 12 months by an accredited tester.
Shut-off / On-off valve: These valves are either completely open or closed. Examples: Gate valve, ball valve, globe valve, angle valve, pinch valve, diaphragm valve; Check valve: Allows flow only in a single direction; Steam conditioning valve: Regulates the pressure and temperature of inlet media to required parameters at outlet.
[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 ...