Ball valve selection


Ball valves are evolved from plug valves. It has the sa […]

Ball valves are evolved from plug valves. It has the same 90-degree rotating movement, the difference is that the cock body is a sphere with a circular through hole or channel passing through its axis. The ratio of the spherical surface to the channel opening should be such that when the ball rotates 90 degrees, all the spherical surfaces should be present at the inlet and outlet, thereby intercepting the flow. The ball valve only needs to be operated with a rotation of 90 degrees and a small turning torque to close tightly. The completely equal valve body cavity provides a direct flow channel with little resistance for the medium. It is generally considered that the ball valve is most suitable for direct opening and closing, but recent developments have designed the ball valve to make it throttle and control flow. The main feature of the ball valve is its compact structure, easy to operate and maintain, suitable for general working media such as water, solvents, acids and natural gas, and also suitable for media with harsh working conditions, such as oxygen, hydrogen peroxide, methane and ethylene. The ball valve body can be integral or combined. Select the valve according to the prevention of medium backflow The role of this type of valve is to only allow the medium to flow in one direction, and prevent the direction of flow. Usually this kind of valve works automatically. Under the action of the fluid pressure flowing in one direction, the valve flap opens; when the fluid flows in the opposite direction, the self-coincidence of the fluid pressure and the valve flap acts on the valve seat, thereby cutting off the flow.

The check valve belongs to this type of valve, which includes a swing check valve and a lift check valve. The swing check valve has a hinge mechanism, and a flap like a door freely rests on the inclined seat surface. In order to ensure that the valve flap can reach the proper position of the valve seat surface every time, the valve flap is designed in the hinge mechanism, so that the valve flap has enough unscrewed space, and the valve flap is truly and fully contacted with the valve seat. The valve flap can be made entirely of metal, or it can be inlaid with leather, rubber, or a synthetic cover, depending on the performance requirements. When the swing check valve is fully open, the fluid pressure is almost unimpeded, so the pressure drop through the valve is relatively small. The valve seat of the lift check valve is located on the sealing surface of the valve seat on the valve body. Except for the valve flap which can be lifted and lowered freely, the rest of the valve is like a shut-off valve. The fluid pressure lifts the valve flap from the sealing surface of the valve seat. The medium backflow causes the valve flap to fall back to the valve seat and cut off the flow. According to the conditions of use, the valve flap can be an all-metal structure, or in the form of a rubber pad or rubber ring inlaid on the valve flap holder. Pneumatic valve is like a shut-off valve, the passage of fluid through the lift check valve is also narrow, so the pressure drop through the lift check valve is larger than that of the swing check valve, and the flow of the swing check valve is subject to Has very few restrictions. Select the valve according to the adjustment media parameters In the production process, in order to make the media pressure, flow and other parameters meet the requirements of the process flow, it is necessary to install an adjustment mechanism to adjust the above parameters. The main working principle of the adjustment mechanism is to change the flow area between the valve flap and the valve flap and the valve seat to achieve the purpose of adjusting the above parameters. These valves are collectively referred to as control valves, which are divided into self-driven control valves such as pressure reducing valves and pressure regulators that rely on the power of the medium itself. Air Operated Valve and hydraulic) are called other-driven control valves, such as electric regulating valve, pneumatic regulating valve and hydraulic regulating valve.