In the water supply system's pipelines, pump rooms and filter tanks, gate valves are often used as important control and regulation equipment. The technical progress development plan for China's urban water supply industry suggests that soft-sealed valves should be used as much as possible for valves with a diameter of 600mm or less, and metal-seated gate valves should be gradually replaced with soft-sealed gate valves. The rubber sealing structure of soft-sealed gate valves is more suitable for use in water supply systems than metal-seated gate valves. 

Rubber sealing rings used in pipelines belong to static sealing methods. After the pipeline installation is completed, except for the slow movement between the rubber sealing ring and the interface caused by pipeline settlement, the rubber is only in a static compression state. Most water supply networks are buried underground, and factors such as temperature, ultraviolet rays, and oxidation have a minimal impact on the aging of the sealing rings. Rubber sealing parts for valves generally belong to dynamic sealing. The force conditions and surrounding environment are complex, making them prone to excessive compression, reduced resilience, and easy wear, which can cause sealing leakage. Therefore, to solve the problems of easy aging of rubber sealing parts for valves, permanent deformation after long-term use, and reduced sealing effect, it is first necessary to put forward corresponding physical performance requirements for the materials based on the different usage parts of the rubber sealing parts for valves.
The appearance of rubber products is relatively similar, but there are huge differences in their internal quality. To avoid the problem of rubber seal contamination, rubber sealing parts that come into direct contact with the medium must be made of non-toxic materials, and the use of recycled rubber is strictly prohibited. For drinking water requirements, they must pass the relevant tests. 

The safety evaluation standards for potable water distribution equipment and protective materials or the non-metallic product tests for the impact on water quality and the suitability for contact with the human body should be non-toxic.
When designing or selecting rubber sealing parts for water supply valves, multiple aspects should be considered.
Safe and reliable: It can still ensure sealing performance under normal operation or when pressure and temperature fluctuate.
Long service life: Reduce the squeezing force to lower the torque, and the rubber can self-compensate after wear.
Simple structure: Easy to install, disassemble and maintain, and can be reused multiple times.
Compact size: Few sealing components, and the fasteners should be lightweight or avoided as much as possible.
Convenient manufacturing: No need for extremely high precision, and low cost. 

The comprehensive requirements for valves in the urban water supply industry are simple and reliable structure, excellent performance, flexible operation, easy maintenance, hygienic water quality, energy conservation and long service life. Rubber seals, as the main soft sealing type for medium and low pressure valves, are the best choice for valves in the urban water supply industry.