Today, I will talk to you about the key points of valve selection for water supply and drainage systems. The small valve allows you to have an in-depth understanding of water supply and drainage valve selection through question and answer methods. Let’s get started!
Q: What is the principle of valve selection in the water supply and drainage system?
1. Gate valves should be preferred for valves of DN300 and below.
2. Butterfly valves should be preferred for DN600 and above valves.
3. DN300 to DN600 valves can choose gate valve or butterfly valve according to the situation.
Q: What are the design and manufacturing standards for butterfly valves for water supply and drainage?
The design and manufacture standard of butterfly valve for water supply and drainage is CJ/T261-2007.
1. The surface of all castings should be clean and smooth, and there should be no air bubbles, blisters, cracks, scars, burrs or other defects that affect the use of the sealing surface and moving parts. Minor defects such as air bubbles and wounds in other parts can be repaired by electric welding or filled with epoxy resin after approval by the purchaser.
2. The casting surface of the shell and valve core should be sand blasted (shot blasted) to remove scale, rust, oil and other sundries, and meet the requirements of Sa2½ surface treatment level in GB/T 8921.1-2011, and should be sand blasted Paint within 6 hours. BHy Bend Valve
3. The coating should adopt non-toxic epoxy resin powder electrostatic spraying or powder dipping process. After the coating is cured, the surface should be uniform, smooth, and free of defects such as pinholes, spray leakage and sundries.
4. The thickness of the inner surface coating should not be less than 0.25mm, the outer surface should not be less than 0.15mm, the coating thickness of the direct buried valve, the inner and outer surfaces should not be less than 0.3mm.
Q: What are the material requirements for the water supply and drainage valve stem?
Small valves: The valve stem (shaft) should be made of stainless steel with a chromium content of not less than 13%. After quenching and tempering, the hardness should reach HBS200-HBS280, and it should meet the requirements of GB/T 1220.
The above is the selection knowledge of water supply and drainage system valves shared with you by small valves through collecting and sorting out data. Valve selection is a relatively professional job. If you encounter any problems during the selection process, you can consult the small valve! The little valve will definitely answer for you carefully!