4. Hard seal pneumatic ball valve shall be used as far as possible for pneumatic cut-off valve
The lower the leakage of the emergency cut-off valve, the higher the leakage. The leakage of the soft sealing valve is the least. The actual disconnection effect may be good, but it is not abrasion resistant and has poor credibility. Seen from the double standards of small leakage and reliable sealing, soft sealing disconnection is not better than hard sealing disconnection. For example, the multi-functional ultra light regulating valve has high reliability and high leakage rate of 10-7, which can already meet the requirements of emergency cut-off valve.

Analysis of hose influence situation
China is a big country of consumption and export, among which most of the pneumatic butterfly valves sold globally are consumed and exported from China, which once became the world's major supplier of pneumatic butterfly valves. Although China's pneumatic butterfly valve industry has a large scope, many pneumatic butterfly valve consumer enterprises often lack central competitiveness and are difficult to become bigger and stronger due to weak technological innovation ability, too single market structure, weak brand influence and other factors.
The sales volume of stainless steel hose is 14.5 billion yuan, of which the proportion of threaded stainless steel hose is less than 25%, which is not only far from the structure of hose products in the international market, but also cannot meet the growing demand of domestic manufacturing industry for stainless steel hose.
In 2010, the structural imbalance of pneumatic butterfly valve was the wrong way between consumption hose and demand. For example, the gap of optical fiber maintenance hose required by users is large, but the consumption of galvanized pneumatic butterfly valve is excessive; The double button stainless steel hose urgently needed by modern manufacturing industry is in great demand, but the low-grade single button stainless steel hose is overspent.