Sanitary Diaphragm Valve is a common valve used in sanitary piping systems. Its design principles and working principles are as follows:

Design principles:
1. Sanitary diaphragm valves should comply with relevant sanitary standards and specifications, such as European sanitary standard EN11866 and American sanitary standard 3A.
2. The valve body and valve cover materials should be stainless steel or other materials suitable for sanitary requirements, and the surface should be smooth, free of burrs, cracks and other defects.
3. The diaphragm material should have good elasticity and corrosion resistance, such as EPDM, silicone, etc.
4. The interface form should adopt sanitary flange or clamping interface.
5. The internal structure of the diaphragm valve should be simple, easy to clean and maintain.

Working principle:
When the sanitary diaphragm valve is working, the valve stem is driven downward by compressed air or motor to close the valve. When the valve stem moves upward, the diaphragm is lifted upward by the nut at the bottom of the valve stem, thereby opening the valve. During the opening and closing process of the valve, the diaphragm is in contact with the medium, which requires the diaphragm to have certain corrosion resistance and wear resistance.

The main advantages of sanitary diaphragm valves include:
1. The valve interior is easy to clean and maintain.
2. The diaphragm is isolated from the medium, avoiding medium leakage and cross contamination.
3. The valve has good sealing performance and can effectively control flow and pressure.
4. High reliability, suitable for the treatment of special media such as high viscosity and high solid content.
In short, sanitary diaphragm valves are widely used in food, pharmaceutical, chemical and other industries. Its design principles and working principles are based on hygiene and safety considerations.