The valve industry has been able to produce a wide range of gate valves, globe valves, throttle valves, plug valves, ball valves, electric valves, diaphragm valves, check valves, safety valves, pressure reducing valves, steam traps and emergency shut-off valves. 12 categories, more than 3,000 models, more than 4,000 valves; the highest working pressure is 600MPa, the maximum nominal diameter is 5350mm, the maximum working temperature is 1200 °C, the minimum working temperature is -196 °C, the medium is water , steam, oil, natural gas, highly corrosive media (such as concentrated nitric acid, medium concentration sulfuric acid, etc.), flammable media (such as stupid, ethylene, etc.), toxic media (such as hydrogen sulfide), explosive media and radioactive media ( Metal sodium, - circuit pure water, etc.). Valve pressure parts are made of brass, cast iron, ductile iron, high silicon cast iron, cast steel, forged steel, high/low alloy steel, stainless steel 304, stainless acid resistant steel, duplex stainless steel, titanium alloy, etc. Electric, pneumatic, manual, hydraulic valve drive. Faced with such a large number of valve types and such complicated working conditions, it is necessary to select the most suitable valve products for the piping system. First, the characteristics of the valve should be understood. Secondly, the steps and basis for selecting the valve should be mastered. the rules.