The plug valve is a shut-off or plunger-shaped rotary valve. The passage port on the valve plug is the same as or separated from the passage port on the valve body by rotating 90 degrees to achieve opening or closing. The shape of the plug of the plug valve can be cylindrical or conical. In a cylindrical valve plug, the channel is generally rectangular; in a tapered valve plug, the channel is trapezoidal. These shapes make the structure of the plug valve lighter, but at the same time it also produces a certain loss. The plug valve is most suitable as a shut-off and connection medium and a shunt application, but depending on the applicable properties and the erosion resistance of the sealing surface, it can sometimes be used for throttling. Turn the plug clockwise to make the groove parallel to the pipe to open, and turn the plug 90 degrees counterclockwise to make the groove perpendicular to the pipe to close.

Main classification of plug valves

One, tight-fitting plug valve

The tight-fitting plug valve is usually used in low-pressure straight-through pipelines. The sealing performance depends entirely on the goodness of the fit between the plug and the plug body. The compression of the sealing surface is achieved by tightening the lower nut. Generally used for PN≤0.6Mpa.

2. Packing plug valve

Packing type plug valve is to realize the seal between the plug and the plug body by compressing the packing. Due to the packing, the sealing performance is better. Usually, this kind of plug valve has a packing gland, and the plug does not need to extend out of the valve body, thus reducing a leakage path of the working medium. This kind of plug valve is widely used for pressure of PN≤1Mpa.

Three, self-sealing plug valve

The self-sealing plug valve realizes the compression and sealing between the plug and the plug body through the pressure of the medium itself. The small head of the stopper extends upwards out of the body, and the medium enters the big head of the stopper through the small hole at the entrance, and presses the stopper upwards. This structure is generally used for air medium.

Four, oil-sealed plug valve

In recent years, the application range of plug valves has continued to expand, and oil-sealed plug valves with forced lubrication have appeared. Due to forced lubrication, an oil film is formed between the plug and the sealing surface of the plug body. In this way, the sealing performance is better, the opening and closing is labor-saving, and the sealing surface is prevented from being damaged.