The working principle and characteristics of Plug Rotary control valve ( plug valve )

The main part of the plug valve is a rotatable conical plug ( plug ) in the shape of a truncated cone, with a medium channel inside, a rectangular cross section , and a hole in the middle of the channel perpendicular to the axis of the plug. When the plug rotates 90 degrees, the fluid channel All closed, the plug valve is a valve that uses a taper plug with a hole to control the opening and closing. Table taper plug and the valve body a conical surface forming a nip with the surface, the upper portion of the valve body with a filler plug the gap between the seal and the valve body. An upper plug has mortise and tenon, the rotation of the square hole plugs with a special wrench used . By the rotation angle to open and close the valve . Types are : straight-through cock, three-way cock and four-way cock, etc. It is characterized by simple structure, open and close rapidly, small resistance, but turning laborious research overhaul grinding cock costs of working hours. Plug valve original design from ball valve. Besides plug valve Cowinns also has advantage on NPT 3pc titanium ball valve design.

1. The working principle and characteristics stopcock stopcock cock through holes with a valve opening and closing member. The cock rotates with the valve stem to realize the opening and closing action. The small plug valve without packing is also called " Cock " . The cock of the plug valve is mostly a cone ( also a cylinder ) , which cooperates with the cone hole surface of the valve body to form a sealing pair. The plug valve is the earliest valve used. The plug valve has a simple structure, small size, fast opening and closing, and low fluid flow resistance, but it is difficult to process and maintain the sealing surface. Ordinary plug valves rely on the precision machining between the metal plug body and the valve body
It is sealed by direct contact, so the sealing performance is poor, the opening and closing force is large, a large rotating torque is required, and it is easy to wear. Usually it can only be used in low pressure ( less than or equal to 1MPa) , small diameter (<100mm) and low temperature (<150 degrees Celsius ) occasions. Not suitable for high temperature, temperature and large-scale changes and easily stuck.

2. The main advantages of the plug valve are as follows :

(1) The plug valve is used for frequent operation, opening and closing quickly and lightly.

(2) The plug valve has low fluid resistance.

(3) The plug valve has simple structure, relatively small size, light weight and easy maintenance.

(4) It is not restricted by the installation direction, and the flow direction of the medium can be arbitrary.

(5) No vibration and low noise.