Quick-cut ball valves are a type of actuator in the automation system. They are composed of a multi-spring pneumatic diaphragm actuator or a floating piston actuator and a regulating valve. They receive signals from regulating instruments to control the cut-off, connection or switching of fluids in the process pipeline. They have the characteristics of simple structure and sensitive response.

The air source of the quick-cut ball valve requires filtered compressed air, and the medium flowing through the valve body should be liquid and gas without impurities and particles. According to the allowable pressure difference, medium characteristics and process pipeline requirements, single-seat, sleeve and three-way cut-off valves can be selected.

Basis for selecting quick-cut ball valves:

1. Selection of structural type

In terms of cutting effect, the angle stroke valve has a simpler structure and a more superior sealing effect than the straight stroke valve. The more representative ones are three-eccentric hard-sealed butterfly valves and ball valves.

2. Selection of sealing materials

Except for corrosion-resistant lined valves, general soft-sealed valves refer to valves in which one of the valve core or valve seat is sealed with non-metallic materials. The sealing effect of soft sealing valve is the best, but more or less unclean debris may be left during pipeline installation and system cleaning. When they flow through the regulating valve, they are easy to scratch the soft sealing valve seat or valve core, increasing the leakage and poor sealing. Therefore, the selection of soft sealing structure must consider the cleanliness of the medium and the strict flushing of the pipeline before commissioning.

3. Selection of sealing surface

1) Spherical sealing

The spherical surface of the sphere is tangent to the fixed small cone surface of the valve, and there is a line contact between them, which is better than the above-mentioned face-to-face sealing effect. Ball valves, spherical sealing butterfly valves, etc. are made with this idea, and their leakage rate can reach 10-6~10-8. High-performance three-eccentric butterfly valves can reach 10-8, or even 0 leakage.

2) Face-to-face sealing

The common plunger valve core has a sealing surface of a 60° small cone surface. The width of this small cone surface is usually between 0.5mm and 2mm. To seal well, it is necessary to ensure that the two cone surfaces are in good contact. But in fact, it is always affected by the processing error, and its sealing effect is not very ideal. The leakage rate of this type of valve is usually 10-4, but it can reach 10-6 after precision grinding, which can reach a higher sealing level.