The plugs here have a hollow passage through them. This passage allows passage of fluids when the valve is opened.
The good thing with plug valves is that they are simple to operate as well as they are affordable.
A common feature in these valves is that they lack the bonnets. Rather, the plug valves come with their handle on the end of the plug exposed from outside. In most cases, the handle and the stem come as single piece thus absence of a stem. It is mainly fixed as an L-shaped handle for such a plug valve. On the contrary, the opposite end comes with a mechanism to retain the plug within the body though it also exposed.
Different types of plug valves
These valves present in several designs. The most commonly found plug valve is the 2-port valve. This is the simplest type that is also very common in the market. It has two positions: shut, for stopping flow and an open for allowing flow. These ports are on the opposite ends of the body. It is for this reason that the valve is referred to as quarter-turn valve. For most households’ natural gas lines, a brass metallic plug valve is used as a shut-off valve.
The other type of plug valves is the 3-way plug valve. The flow here is directed from port one to either two or port three. Since they are multi-port plug valves, the flow direction could be in any of the three ways. There are stopcocks that are mainly applied in laboratory glassware. These plug bodies are either glass or plastic. If the plug is made of glass, the plug and handle are basically fused together. For special vacuum application, a specially made glass stopcock is designed.
Selecting a Plug valve
Always, it is wise understanding the environment of application before deciding on the type of plug valve to use. The instructions of installation and maintenance are thus very critical before purchasing a plug valve for your system.