Disadvantages:
1. The sealing performance of pneumatic butterfly valve is poorer than that of pneumatic ball valve and pneumatic valve, so it is used in places where the sealing requirements are not very high;
2. Due to the limitation of the structure and sealing material of pneumatic butterfly valve, it is not suitable for high temperature and high pressure pipeline system. The general working temperature is below 300 ℃ and PN40;
3. The flow adjustment range of the pneumatic butterfly valve is small. When the valve is opened up to 30%, the flow will reach nearly 95%; Under certain working conditions, pneumatic butterfly valves and pneumatic ball valves are not allowed to use valves with diameter shrinkage. On the one hand, it is to reduce the resistance loss of the pipeline, and on the other hand, it is to avoid obstacles to mechanical cleaning of the pipeline after the diameter shrinks.

3. The caliber of the range caliber sensor is not necessarily the same as the pipe diameter, but must be determined according to the actual flow rate, and the caliber of the flowmeter shall be selected according to the calculation formula. For industrial transportation of water and other liquids, the general pipeline velocity is 1.5~3m/s. The electromagnetic flowmeter is used in such pipelines, and the sensor diameter is the same as the pipe diameter.