Pneumatic Valve Material

1. The material of the valve body should be mainly nodular cast iron, and the brand and actual physical and chemical testing data of the cast iron should be indicated.
2. The material of the valve stem should be stainless steel (2CR13), and large diameter valves should also have stainless steel embedded valve stems.
3. The nut material is made of cast aluminum brass or cast aluminum bronze, and its hardness and strength are greater than those of the valve stem.
4. The material of the valve stem bushing should have a hardness and strength not greater than that of the valve stem, and should not form electrochemical corrosion with the valve stem and valve body under water immersion conditions.
5. Sealing surface material:
① The types of pneumatic valves vary, and the sealing methods and material requirements vary;
② The material, fixing method, and grinding method of copper rings for ordinary wedge gate valves should be specified;
③ Physical, chemical, and hygiene testing data of soft sealing gate valves and valve plate lining materials;
④ Butterfly valves should indicate the material of the sealing surface on the valve body and the material of the sealing surface on the butterfly plate; Their physical and chemical test data, especially the sanitary requirements, anti-aging performance and wear resistance of rubber; Usually, nitrile rubber and EPDM rubber are used, and the use of recycled rubber is strictly prohibited.
6. Valve shaft packing:
① Due to the infrequent opening and closing of pneumatic valves in the pipeline network, it is required that the filling material should not move or age for several years, and the sealing effect should be maintained for a long time;
② The valve shaft packing should also withstand frequent opening and closing to ensure good sealing effect;
③ In view of the above requirements, the valve shaft packing should strive not to be replaced for life or more than ten years;
④ If the packing needs to be replaced, the design of pneumatic valves should consider measures to replace it under water pressure.