What are the materials of pneumatic valves?

1. The material of the valve body should be mainly ductile iron, and the grade and the actual physical and chemical test data of the cast iron should be indicated.

2. The material of the valve stem should be made of stainless steel (2CR13). Large-diameter valves should also be stainless steel embedded valve stems.

3. The nut 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 hardness and strength of the valve stem bushing should not be greater than that of the valve stem, and the valve stem and valve body will not form electrochemical corrosion under the condition of water immersion.

5. Material of sealing surface:
① There are different types of pneumatic valves, different sealing methods and material requirements;
② For ordinary wedge gate valves, the material, fixing method and grinding method of the copper ring should be explained;
③Physicochemical and hygienic testing data of soft sealing gate valve and valve plate rubber lining material;
④Butterfly valves should be marked with 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 hygienic requirements, anti-aging performance and wear resistance of rubber; usually nitrile rubber and EPDM are used. Rubber, etc., it is strictly forbidden to mix with reclaimed rubber.

6. Valve shaft packing:
①Because the pneumatic valves in the pipe network are usually opened and closed infrequently, the packing is required to be inactive for several years, and the packing will not age, so that the sealing effect can be maintained for a long time;
②The valve shaft packing should also have good sealing effect when it is subjected to frequent opening and closing;
③ In view of the above requirements, the valve shaft packing shall not be replaced for life or more than ten years;
④ If the packing needs to be replaced, the design of the pneumatic valve should consider the measures to be replaced under the condition of water pressure.

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