The commonly used pneumatic butterfly valves are wafer type pneumatic butterfly valve and flange type pneumatic butterfly valve. Wafer type pneumatic butterfly valve can only be connected between two pipe flanges with the help of stud bolts. The flange type pneumatic butterfly valve itself has flanges, which can directly connect the flanges on both ends of the valve to the pipe flanges with bolts.

2. Flow rate, full scale flow, range and caliber The selected instrument caliber is not necessarily the same as the pipe diameter, but depends on the flow. The process industry transports water and other liquids with different viscosity, and the pipeline flow rate is generally 1.5~3m/s. The electromagnetic flowmeter is used on such pipes, and the sensor diameter is the same as the pipe diameter.