Does not affect the water quality is an important indicator of valve selection. The valve directly contact with water is mainly the inner side of the valve body, the sealing part, the valve plate and so on. At present, the sealing part of the valve produced by many manufacturers uses rubber material. The rubber materials commonly used are nitrile butadiene rubber (NBR), neoprene rubber (CR) or ethylene propylene rubber (EPDM). The rubber is synthetic rubber. In the process of synthesis, more than ten kinds of raw materials and additives such as anti-aging agents should be added into the natural rubber. The final synthetic rubber can be used for sealing water supply valves, it must be seen whether the rubber is non-toxic, whether it meets drinking water sanitation standards. As for the inside of the valve and valve plate and other parts, many manufacturers used to paint the method, only consider the rust problem, without considering whether toxic. In practice, we found that: in the water supply pipe network, the lining anticorrosion problem of the pipe is solved, but the pipe network valve is not lined, because of the water precipitation phenomenon and the erosion and deposition of iron bacteria in the water to the valve cavity and valve plate, resulting in some of the valve body wall appear hilly accumulation phenomenon. It not only affects the water quality of the water supply, but also one of the main reasons why some valves are not strictly closed. Therefore, we require that these parts in direct contact with water should be sprayed with non-toxic paint, preferably with non-toxic epoxy powder by electrostatic spraying. When we choose the valve, we should first check whether there is a non-toxic proof and inspection certificate of rubber and paint, only with the above conditions of the valve, in order to ensure that water quality is not polluted, to ensure the safety of water supply.
