A plug valve is like a ball valve
except that it has a tapered conical plug instead of a ball. The main advantage of this is that the body cavity
in a plug valve will not become filled with the media which is what happens in ball valve. Between the plug and the body, a teflon
seat is placed to prevent leakage. Because of the large surface
area of the seat, the torque required to open these valves is very high.
Plug valves come in a range of sizes from 1/2" to 16" and can be manual or automated. The materials of construction range from carbon steel to titanium.