Plug valve may be defined as a type of valve which consists of cylindrical or conically narrowed plugs. These plugs can be rotated inside the valve in order to control and regulate the flow of fluid within the valve. Plug valves are designed to be simple and as a matter of fact they are very economical. The key thing about the plugs in these valves is that they have number of hollow passage ways going to one side via the plug and this helps the fluid to flow through the valve when it is open.

Structure of plug valve

The structure of the plug valve is made straightforward. When the plug is conical, the stem is attached to the larger end of the plug. Though the plug valves do not have bonnets, they have handles at the end of the plugs. Usually the stem and the handle are designed to be a single piece to be attached to the end of the plug. The other end of the plugs in these valves is often exposed outside, but the plugs are retained inside the body.

The most general type of plug valve is the 2 port valve. Here, there is only two positions open and shut. The open position is for allowing the flow of fluid and the shut position is for stopping the flow of the fluid. The ports are the holes through which the fluid can enter or exit the valves. The plug inside the 2 port valve has a single passageway for fluid going through it. The ports are usually positioned at the alternate ends of the body. This requires the plug inside it to rotate a one fourth of a full turn in order to switch between the two positions of the valve. This is why the plug valves are quarter turn valves.

Applications of plug valve

The slightly conical plug valve made up of metal is typically used as the shut off valve in most of the household gas lines. Another important application for the plug valves is that they are used as stopcocks in the laboratory glassware.