Pneumatic ball valve is a kind of pneumatic actuator widely used in modern automatic control system. The control signal drives the ball valve switching action through the pneumatic actuator to complete the switching control or adjustment control of the medium in the pipeline. 　　 　　

      The first point: the selection of ball valves 　　 　　

      Connection method: flange connection, clamp connection, internal thread connection, external thread connection, quick installation connection, welding connection (butt welded connection, socket welding connection) Valve seat sealing: metal hard seal ball valve, that is, the sealing surface of the valve seat and the ball sealing surface are metal-to-metal ball valves. Suitable for high temperatures, containing solid particles, and abrasion resistance. Soft seal ball valve, the valve seat is made of PTFE, para-polyphenylene PPL elastic sealing material, the sealing effect is good, and zero leakage can be achieved. 　　 　　

      Valve material: WCB cast steel, low temperature steel, stainless steel 304, 304L, 316, 316L, duplex steel, titanium alloy, etc. 　　 　　

      Operating temperature: normal temperature ball valve, -40 °C ~ 120 °C. Medium temperature ball valve, 120~450 °C. High temperature ball valve, ≥ 450°C. Low temperature ball valve -100~-40 °C. Ultra-low temperature ball valve≤ 100°C. 　　 　　Working pressure: low pressure ball valve, nominal pressure PN≤1.6MPa. Medium pressure ball valve, nominal pressure 2.0-6.4MPa. High pressure ball valve ≥ 10MPa. Vacuum ball valves, ball valves below one atmosphere. 　　 　　

      Structural form: floating ball valve, fixed ball valve, V-shaped ball valve, eccentric hemisphere valve, rotary ball valve. 　　

      Flow channel form: straight-through ball valve, three-way ball valve (L-shaped flow channel, T-shaped flow channel), four-way ball valve