Ball valves are evolved from plug valves. It has the same rotation of 90 degrees, except that the plug body is a sphere with a circular through hole or its axis. The ratio of the spherical surface to the passage opening should be such that when the ball is rotated 90 degrees, the spherical surface should be entirely present at the inlet and outlet to intercept the flow.

The working principle of the swing check valve is somewhat similar to the shut-off valve. The passage of the fluid through the lift check valve is also narrow, so the pressure through the lift check valve is larger than that of the swing check valve, and the swing is started. The flow rate of the check valve is limited.

Piston-type check valves are automatic valves that open under the pressure of fluid in one direction, and the valve flaps to prevent its flow when the fluid flows in the opposite direction.

Check valve is a valve in which the opening and closing member is a circular valve flap and acts on its own weight and medium pressure to block the reverse flow of the medium. It is an automatic valve, also known as a check valve, non return valve or isolation valve.

The closing of the butterfly valve online (disc) in the middle of the medium, when the design should consider the influence of the convective resistance.

The butterfly valve has a small flow resistance when fully opened. When the opening is between about 15° and 70°, sensitive flow control is possible, so the application of butterfly valves is very common in the field of large-diameter adjustment.

The ball of the floating ball valve is floating without a mounted shaft. Under the action of the medium pressure, the ball can generate a certain displacement and press on the sealing ring at the outlet end to ensure the sealing of the outlet end, which is a single-sided forced seal.

The floating ball valve has a simple structure and good sealing performance, but the load of the ball subjected to the working medium is all transmitted to the outlet sealing ring, so it is necessary to consider whether the sealing ring material can withstand the working load of the spherical medium.

The valve flap of the swing check valve is disc-shaped and rotates around the shaft of the valve seat passage. The flow passage is streamlined and the flow resistance is smaller than that of the butterfly check valve. It is suitable for low flow rate and irregular flow.

The isolation valve belongs to the on/off type valve, which is only in the open or closed state. Isolation valve is basically has a requirement for the leak level. Relatively speaking, the safety requirements are higher than that of the on/off valve, and some parts have higher requirements.