How many solenoid valves are needed to control the opening and closing of pneumatic sanitary butterfly valve? Although multiple seals are expensive, difficult to process, and the application and design requirements of medium and high temperature pneumatic ball valves in foreign power plants are limited, they can increase the flow capacity of pneumatic ball valves. The concentric metal ring of this kind of seal is pressed to the ball by pipeline pressure, so as to squeeze the non-metallic seal ring and make the ball form a more tight seal than the metal ring. The high temperature pneumatic ball valve used for throttling abroad is generally l0.5MPa 441 ℃ (825F)+the pressure difference is 3.4MPa. The temperature difference is 243 C (470 F) for valves at 649 ℃ (1200 F) and 32 MPa. The valve body is made of chromium molybdenum alloy, the ball is made of 410 stainless steel, the surface is welded with hard alloy and then plated with chromium, and the seal ring is made of stellite
2. Working principle of pneumatic control valve: 4-20ma current signal is sent from industrial control systems such as DCS, PLC and other systems to pneumatic control valve positioner. The positioner automatically adjusts the compressed air volume (pressure) according to the current value received, and sends the compressed air to the upper/lower chamber of the membrane chamber.
When the air pressure in the membrane chamber is greater than the elastic range of the spring, the pressure inside the valve body and other resistances, the valve core, valve stem, push rod and other components can be pushed to move freely.
