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An isolation valve is a valve in a fluid handling system that stops the flow of process media to a given location, usually for maintenance or safety purposes. [1] They can also be used to provide flow logic (selecting one flow path versus another), and to connect external equipment to a system. [ 2 ]
Two block valves and a bleed valve are as a unit, or manifold, to be installed for positive isolation. Used for critical process service, DBB valves are for high pressure systems or toxic/hazardous fluid processes. Applications that use DBB valves include instrument drain, chemical injection connection, chemical seal isolation, and gauge isolation.
The quantity of bleed air flowing to the AC pack is regulated by the flow control valve (FCV). One FCV is installed for each PACK. A normally closed isolation valve prevents air from the left bleed system from reaching the right PACK (and vice versa), although this valve may be opened in the event of loss of one bleed system.
Piping and instrumentation diagram of pump with storage tank. Symbols according to EN ISO 10628 and EN 62424. A more complex example of a P&ID. A piping and instrumentation diagram (P&ID) is defined as follows: A diagram which shows the interconnection of process equipment and the instrumentation used to control the process.
A second function of the PCV valve is to act as a flame arrester and to prevent positive pressure from the intake system from entering the crankcase. This can happen on turbocharged engines or when a backfire takes place, and the positive pressure could damage the crankcase seals and gaskets, or even cause a crankcase explosion. The PCV valve ...
A blowdown valve (BDV) is a type of shutdown valve designed to depressurize a pressure vessel by directing vapour to a flare, vent or blowdown stack in an emergency. BDVs fail-safe to the open position upon failure of the control system. [1] The type of valve, type of actuation and performance measurement are similar to an ESD valve.
The containment isolation valves may also close on a variety of other signals such as the containment high pressure experienced during a high-energy line break (e.g. main steam or feedwater lines). The containment building serves to contain the steam/resultant pressure, but there is typically no radiological consequences associated with such a ...
Unlike a ball valve, the disc is always present within the flow, so it induces a pressure drop, even when open. A butterfly valve is from a family of valves called quarter-turn valves. In operation, the valve is fully open or closed when the disc is rotated a quarter turn. The "butterfly" is a metal disc mounted on a rod. When the valve is ...