Spherical check valve

1. Overview of Spherical Check Valves
Spherical check valves are widely used in devices such as petroleum, chemical, and power heating boilers. They are mainly used to prevent the reverse flow of media in pipelines and protect the safe operation of equipment. They are ideal check devices for pipelines. However, at present, the common check valve structures include swing type and lift type, etc. Due to the problems of easy jamming, poor sealing and difficult maintenance of these common types of check valves, and the fact that they may cause serious water hammer when closing by themselves, and the water hammer pressure far exceeds the working pressure of the system, it may endanger the safety of the system. Therefore, in addition to meeting the basic requirements of flow rate, the design of a check valve is most importantly about the size of the flow resistance and whether there is any overflow or vortex. This is related to energy consumption and also affects the level of production cost and the competitiveness of the product. The new type of spherical check valve is designed based on the theory of reducing flow resistance and eliminating water hammer.
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2. Structural features of spherical check valves
The spherical check valve has no transmission parts in structure and a free opening and closing structure, so there is no wear on the shaft and shaft sleeve. The valve disc rotates automatically in the spherical track, constantly updating the sealing surface, and there are no fixed wear points. During operation, the spherical surface wears evenly and always maintains a high shape accuracy. Its performance will not decline over time, thus extending the service life of the seal. The surface of the valve disc is lined with rubber. The dimensional accuracy and surface roughness of the ball can be controlled by the rubber-lined mold. The processing accuracy requirements for the ball are reduced, and it can be reused, which lowers the cost of the valve disc. The rubber on the surface of the steel ball can elastically deform, absorb and reduce vibration, and play a certain buffering role. The low density of rubber makes the inertia of the valve disc movement small and the action sensitive. The sphere adopts a hollow structure, which is light in weight and reduces the impact force of the valve disc on the valve seat when closing. The inner diameter of the spherical track is designed to be larger than the pipe diameter of the corresponding flange, increasing the flow cross-section, reducing the medium resistance and pressure drop. When the sealing structure is designed according to the corresponding flange, the working pressure is vacuum to medium pressure. Under the condition that the installation is not restricted, the spherical check valve can be installed either horizontally or vertically. Moreover, this valve is convenient to maintain on the pipeline. Only the lower valve disc needs to be replaced.
3. Working Principle of Spherical Check Valve
Spherical check valve
The spherical check valve shown in the above figure consists of a valve body, a valve seat 2, a valve cover 7, and a valve disc. The valve body is composed of a left valve body 5 and a right valve body 1. The right valve body is the medium inlet end, and the left valve body is the medium outlet end. The valve seat 2 is installed between the left valve body 5 and the right valve body 1. The valve disc is a sphere 3. The sealing surface of the valve seat 2 is a spherical surface that fits with the surface of the sphere 3. The left valve body is composed of a fluid channel and a sphere track. The centerline of the sphere track forms an acute Angle with the centerline of the fluid channel. The Angle design of this acute Angle is determined based on whether the valve disc 3 can rise and fall flexibly within the sphere track. At the intersection of the fluid channel and the spherical track, an arc-shaped filter screen 6 is set. This arc-shaped filter screen 6 has the same curvature as the inner wall of the spherical track, so that the inner arc of the arc-shaped filter screen 6 and the inner wall of the spherical track form an integral inner cylindrical surface, creating a smooth rolling channel for the valve disc 3. It not only does not affect the flow of the medium but also enables the valve disc 3 to roll flexibly.

This spherical check valve automatically controls the rolling position of the sphere within the spherical track by utilizing the thrust of the medium and the gravity of the valve disc. When the medium flows forward, the thrust of the medium pushes the valve disc to roll to the upper end of the spherical track. When the forward thrust of the medium disappears, the valve disc rolls off the upper end of the spherical track to seal and fit with the valve seat. It has the advantages of simple structure, the sphere is not easy to be stuck in the spherical track, good sealing reliability and small water hammer.