Plug valve is a rotary control valve which is used to control flow. Plug valves are simple and often economical. The plug valve is much similar to the globe valve.
Construction and working:
The simplest form of a plug valve is the petcock. The body of a plug valve is machined to receive the tapered or cylindrical plug. The disk is a solid plug with a bored passage at a right angle to the longitudinal axis of the plug. In the open position, the passage in the plug lines up with the inlet and outlet ports of the valve.
When the cap is rotated 90 ° from the open position, the solid part of the cap blocks the ports and stops the flow of fluid. The plug valves are available in a lubricated or non-lubricated design and with a variety of styles of port openings through the plug, as well as a number of plug designs.
Plug valves are normally used in operations without throttling, especially when a frequent operation of the valve is necessary.
An important feature of the plug valve is its easy adaptation to the multiport construction. Multiport valves are widely used. Its installation simplifies the pipes and provides a more convenient operation than multiple gate valves. They also eliminate pipe fittings. The use of a multi-port valve, depending on the number of ports in the plug valve, eliminates the need for up to four conventional shut-off valves.
Multiport Plug Valves:
Multiport valves are particularly advantageous in transfer lines and to divert services. A single multiport valve can be installed instead of three or four gate valves or other types of a shut-off valve. One disadvantage is that many multiport valve configurations do not completely shut off the flow.
In most cases, one flow path is always open. These valves are intended to divert the flow of one line while shutting off flow from the other lines. If complete shutoff of flow is a requirement, it is necessary that a style of multiport valve be used that permits this, or a secondary valve should be installed on the mainline ahead of the multiport valve to permit complete shutoff of flow.
- Gas and liquid fuel control
- At boiler feed water
- low preassure steam.
- For extreme temperature flow.