Difference Between Ball Valve and Plug Valve
When used for cutting, the plug valve has a slightly better adjustment ability than ball valve, but the advantage is limited, since the plug valve is much bigger than the ball valve, the sealing effect is good, but it also causes too much torque and not enough flexibility. The conventional positive cock structure is difficult to achieve because of its weight.
If a large size valve is to be used, the reverse cock structure must be used, the head of the cocks is downward, so that the sealing effect will be reduced under the force of gravity, so it should be sealed with grease. The injected grease causes the valve to be used only for natural gas, oil storage, and transportation, not for other industries, because the grease can contaminate the medium. And the ball valve, although the sealing effect is a little worse in theory, it can be made into a big aperture, moreover, with the improvement of machining accuracy and sealing material, the sealing effect of ball valve can meet the practical application requirements well, and it can be applied more widely.
When used for adjustment, both of them are not very different. They can be used to adjust the hole in the rotating body. As a result, general plug valves are used for high-sealing occasions, but generally smaller, and ball valves can be used in more and more extensive industrial occasions.
Plug Valve Function
The plug valve is rotated by the cocks to the center of the valve body to achieve the purpose of opening and closing. Its role is to cut off, divide the field and change the flow of the medium. The structure is simple, the dimensions are small, the operation only has to rotate 90 degrees, the fluid resistance is not big. Its disadvantage is that the switch is arduous, the sealing surface is easy to wear, the high temperature is easy to get stuck, not suitable for regulating the flow. The plug valve, also called cock, revolving door. There are many types of it, like straight type, three-connection type, four-connection type.
The plug cock is a closed or plunger rotary valve. By rotating 90 degrees, the passageway of the plug valve can be communicated or separated from the passageway of the valve body, so that a valve can be opened or closed. The shape of the plug can be cylindrical or conical. In the cylindrical plug valve, the channel is usually rectangular. In the conical plug valve, the channel is a trapezoid. These shapes make the structure of the plug valve lighter. It is most suitable for cutting and connecting medium and distributary. But sometimes it can be used for throttling according to the applicable performance and the erosion resistance of the sealing surface.
Plug Valve Advantages
The plug valve is used for regular operation, and the opening and closing are fast and light.
Low fluid resistance of plug valve.
The valve structure is simple, relatively small, lightweight and easy to maintain.
Good sealing performance
The flow direction of the medium is arbitrary without limitation of the direction of installation.
No vibration, small noise.