One is the general requirements.
1.1 The specifications and types of valves must meet the requirements of the pipeline design documents.
1.2 The valve model should indicate the number requirements of the national standard on which it is based. If it is a corporate standard, the description of the relevant model should be indicated.
3. The working pressure of the valve is required to be ≥ the working pressure of the pipeline. Without affecting the price of the intake solenoid valve, the working pressure that the valve can withstand should be greater than the actual working pressure of the pipeline; when the valve is closed, any side of the valve Should be able to withstand 1.1 times the valve working pressure value without water leakage; when the valve is open, the valve body should be able to withstand twice the valve working pressure requirement.
1.4 The valve manufacturing standard should indicate the national standard number on which it is based. If it is a flange solenoid valve enterprise standard, the enterprise document should be attached to the purchase contract.
The second is the standard quality of the valve.
2.1 The valve body material should be mainly ductile iron, and the grade of the cast iron and the actual data of physical and chemical inspection should be indicated.
2.2 Rod material, strive for stainless steel rods (2CR13), large diameter valves should also use stainless steel sleeve rods.
2.3 Use nut material, cast aluminum brass or cast aluminum bronze, its hardness and strength are greater than the valve stem.
2.4 The material of the valve stem bushing should not have greater hardness and strength than the valve stem, and it should not be electrochemically corroded with the valve stem and valve body under water immersion.
2. Sealing surface material.
②Different valves have different sealing methods and material requirements;
b For general wedge gate valves, the material, fixing method and grinding method of the copper ring should be indicated;
③Physical, chemical and hygienic inspection data of soft-seal gate valve and valve plate lining material;
④The butterfly valve should indicate the material of the valve body and the sealing surface of the butterfly plate, as well as the physical and chemical indicators of the butterfly valve, especially the hygienic requirements of the rubber, aging resistance, and abrasion resistance. Generally, nitrile rubber and EPDM rubber are used. , It is strictly prohibited to mix with reclaimed rubber.