Pneumatic butterfly valve, as a component used to control pipeline flow and make and break, has been widely used in many fields such as petroleum, chemical industry, metallurgy, hydropower and so on. Among the known pneumatic butterfly valve technologies, the sealing forms of pneumatic butterfly valves include soft sealing and hard sealing. The sealing materials of soft sealing surfaces are mostly rubber, polytetrafluoroethylene, etc., while the hard sealing materials are mostly various alloys and metal materials. Metal sealed valves generally have longer service life than elastic sealed valves, but it is difficult to achieve complete sealing.

Some models of instruments claim to have a higher * * degree, with a basic error of only (± 0.2%~± 0.3%) R. However, there are strict installation requirements and reference conditions, such as the ambient temperature of 20~22 ℃, the length of the front and rear straight pipe sections are required to be greater than 10D, 3D (usually 5D, 2D) and even proposed that the flow sensor should be integrated with the front and rear straight pipes for real flow calibration on the flow standard device, To reduce the impact of poor clamping. Therefore, when selecting and comparing multiple models, do not just look at high indicators, but read the manufacturer's samples or instructions in detail for comprehensive analysis.