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.

How to select materials for large diameter pneumatic butterfly valves?
How to select materials for large diameter pneumatic butterfly valves? In recent years, with the growing application market of pneumatic butterfly valves, there are also higher requirements for the process. For large diameter pneumatic butterfly valves, friends are always hesitant when using them. Such a large diameter has high cost. If 304 or better material 316 316L is used, wouldn't the cost be higher?
The pipe with diameter above DN150 is basically a large-diameter pipe. For the material, according to the response of customers and users for many years, I have informed you of some tips that few people in the industry know. For the corrugated pneumatic butterfly valve with diameter above DN200, the pipe blank, that is, the corrugated pipe inside, must be made of 304 or more materials, First of all, no matter where the user uses the product, this layer directly contacts the medium, no matter whether the medium is water, steam, oil or air, it will have its performance, rust prevention, corrosion prevention, high temperature resistance, etc. In the case of stainless steel wire mesh cover, this layer can be made of ordinary stainless steel, and under high pressure, it will be two layers of steel mesh cover and steel belt, The largest model is 800 caliber, and advanced equipment and intact testing equipment can be carbon steel and stainless steel flanges according to the customer's application status. Wide users of large caliber stainless steel pneumatic butterfly valves must find the manufacturers on the right track for consumption to ensure quality and application.
Our company has long supplied the application of stainless steel pneumatic butterfly valves to large-scale units such as West Open pit, Jiujian, and Paper Mill subordinate to Fukuang Material Supply Branch.