The structure of the pneumatic valve material

1, body material, should give priority to with nodular cast iron, and indicate the brand and the physical and chemical testing data of cast iron practice. 2, the valve stem material, and strive to stainless steel stem ( 2CR13) , large diameter valves also should be embedded package of stainless steel stem. 3, nut material, using aluminum brass or aluminum bronze, and the hardness and strength were greater than the valve stem. 4, the valve stem bushing material, its hardness and strength shall be no greater than the valve stem, and soaking in the water condition and the valve stem, valve body don't form the electrochemical corrosion. 5, and materials of sealing surface differ: 1) pneumatic valves have different categories, different sealing methods and material requirements; (2) normal wedge gate valve, the material of copper ring, fixed way and grinding way shall specify; (3) soft-sealing gate valve, valve plate rubber lining material physical chemistry and health testing data; (4) butterfly valves shall be marked on the valve body sealing materials and sealing surface on the butterfly plate material; Their physical and chemical testing data, especially the health requirements of rubber, ageing resistance, wear resistance; Usually use NBR and epdm and so on, are strictly forbidden to mixed with reclaimed rubber.