When the lift plug valve is opened, the transmission mechanism raises the plug, drives the two sides of the plate together, and then detaches the combined plug body and the valve sealing surface. Then drives the plug to rotate 90 degrees to the fully open position of the valve
When the lift plug valve is closed, the transmission mechanism rotates the combined plug 90° to the closed position, and then pushes the plug down. After the two side plates contact the bottom of the valve body, it does not move down again. The inlet and outlet ends move, so that the soft sealing surface of the side plate contacts the sealing surface of the valve body and is compressed to achieve the seal
The double sealed lift plug valve has double blocking and bleed functions. The plug valve is equipped with a pressure balancing device to prevent abnormal pressure rise of the system and reduce the resistance at the moment of valve opening and closing. Because the metal surfaces contact each other after the sealing ring is compressed, the valve has a fireproof function. The maintenance of the lift plug valve is very convenient. Without removing the plug valve body from the pipeline, the two side plates can be removed and replaced by removing the end cover at the bottom of the valve body. Therefore, doule seal lift plug valve is also widely used in various industries such as petroleum, natural gas, metallurgical mines, gas engineering, light industrial textiles, ship terminals, food and environmental water treatment for regulating and opening and closing pipeline fluids.
Metal Seated Lift Plug Valve
Metal Seated lift plug valve can be sealed on both sides of the seat sealing surface, the use of the valve is not restricted by the flow direction of the medium. When the metal seated lifting plug valve is closed, the sealing surface of the valve seat can be pressurized by the hand wheel and the stem. By increasing the specific sealing pressure, the plug valve can have better sealing performance. The sealing surface of the valve seat is convex, which is convenient for cleaning the sealing surface, and the sealing surface is not easy to accumulate crystalline medium or solid particles. It is often used in high temperature applications in chemical plants.
There are many types of metal seal lift plug valves, and there are two common types.
a. Handwheel and handle lift plug valve.
The working principle: ascending, make the plug and valve fully open. When closing, first turn the handle to turn the cock 90 degrees to the closed position, and then turn the hand wheel to lower the cock to reach the seal.
During the opening and closing of the valve, the plug is separated from the valve seat, so the opening and closing of the valve is very easy. And the sealing surface is scratched proof during the opening or closing process. So the valve has longer life span. However, the driving torque of the handle is small, so the nominal size of the valve is usually not large. The handwheel handle lifting type plug valve has a compact structure, small volume and low fluid resistance.
b. Mechanical cross-drive lifting plug valve.
The working principle of the mechanical cross-drive lifting plug valve is that when the valve is opened, the transmission device turns the thread of the valve stem to make the plug body rise. After the sealing surfaces of the plug and the valve body are separated, the plug is driven to rotate 90 degrees until the valve is fully opened. When closing, the transmission device causes the plug to rotate 90 degrees to the closed position first, and the plug no longer rotates. After the driving force rotates the thread, the plug is lowered and comes into contact with the sealing surface of the valve body to achieve sealing.
The mechanical cross transmission mechanism can be connected to pneumatic actuator, electric motor actuator, hydraulic actuator, etc. for remote control.
The mechanical cross drive lift type plug valve solves the limitation of insufficient input torque of the driving device, and makes the valve develop toward the direction of large diameter and high pressure.
The plug passageway of the mechanical cross drive lifting plug valve is the same as the diameter of the pipeline, and the fluid resistance is small, which is convenient for pigging. The development on oil and gas long-distance pipelines is getting bigger and bigger.
Lift Plug Valve Features
Lift Plug Valve is applicable to the cutting and connection of pipelines medium that aroused in various industries as petroleum, chemical industry, pharmacy, chemical fertilizer, power industry etc.
The features is as below:
1. The product has reasonable structure, reliable sealing, excellent performance and beautiful appearance.
2. Opening and closing of the valve is carried out while the sealed surface is taken off so it will not cause abrasion on the sealed surface.
3. Its characteristic double-direction flow makes installation and use more convenient.
4.The materials of the parts and sizes of flanges can be reasonably configured according the actual operation condition of the requirements of the customers, so as to meet the various needs of engineering.
How Does A Lift Plug Valve Work?
As for the process of opening and closing of the lift plug valve, when opening the plug valve, first of all, turn the hand wheel to make the plug lifted and separated with the sealed surface, then turn the handle by 90° to make the channel of plug to the channel of valve body, so that the lift plug valve is opened; when closing the lift plug valve, first of all, turn the handle by 90° to make the channel of plug vertical to the channel of plug valve body, and then turn the hand wheel to descend the plug, so that the plug valve is closed.
How To Install A Lift Plug Valve?
When installing the lift plug valve, in order to prevent damage to the lift plug valve and ensure the full performance of the lift plug valve, the following four points should be noted:
1） Make sure the lift plug valve is open. First heat up the pipeline and transfer as much heat as possible from the pipe to the valve. Avoid extending the heating time of the plug valve itself.
2） Use gauze or wire brush to remove the pipe and cutting parts to make the metal surface shine. The use of steel wool is not recommended.
3） First cut the pipe in the vertical direction, trim and remove burrs, and measure the pipe diameter
4） Apply flux to the outside of the pipe and the inside of the welding shield. The flux must completely cover the welding surface. Please use flux sparingly.
