How to reasonably and correctly select the model and specification of pneumatic ball valve? According to the different sealing surfaces, pneumatic ball valves can be divided into hard sealing pneumatic ball valves and soft sealing pneumatic ball valves. Hard sealed pneumatic ball valve adopts hardfacing, spraying, nitriding and other hardening technologies to harden the sealing surface of the ball and the sealing surface of the valve seat. The use temperature of hard sealed pneumatic ball valve is much higher than that of sealed pneumatic ball valve in the environment of high temperature and wear resistant media with particles. The soft seal pneumatic ball valve uses PEEK, PTFE, PPL and other engineering plastics as the sealing valve seat. The sealing surface of the ball is generally used in the medium pipeline with a temperature lower than 200? The use temperature does not have different requirements for the pneumatic ball valve. At normal temperature, it usually refers to - 29 ℃ - 200 ℃. Cast steel pneumatic ball valve and soft seal valve seat are usually used. If the temperature is between 200 ℃ and 425 ℃, the cast steel valve body can also be used, but it must be a metal sealing surface. If the temperature exceeds 425 ℃, the chrome molybdenum steel or even stainless steel must be used. Low temperature steel is used as valve body material when the temperature is lower than - 29 ℃ - 46 ℃- The structural materials of low temperature pneumatic ball valves at 46 ℃ - 101 ℃ shall be subject to cryogenic treatment; Austenitic stainless steel must be used as structural material when the temperature is lower than - 101 ℃

2. Protective facilities of safety valve:
Generally, there is no isolating valve before and after the installation method, which can only be used in individual cases. If the medium force contains solid particles, which affects the tightness of the safety valve after it takes off, a gate valve with lead seal shall be installed in front of and behind the safety valve. The gate valve shall be fully open. The gate valve and the safety valve shall be directly installed with a DN20 inspection valve to the atmosphere. When the released wax and other media are solid at room temperature, or the temperature of light liquid and other media is lower than 0 ℃ due to decompression gasification, the safety valve needs steam tracing. For safety valves used in corrosive media, depending on the corrosion resistance of the valve, it is considered to add a corrosion resistant explosion-proof membrane at the valve inlet. The gas safety valve is generally equipped with a bypass valve according to its diameter for manual venting.