The water supply system is an important and indispensable part of production and life,The traditional water supply method covers a large area,the water quality is easy to pollute,the infrastructrue investment is large,and the main disadvantage is that the water pressure cannot be kept constant resulting in some devices not working properly,As the variable-frequency technology matures,variable-frequency constant-pressure water supply equipment fundamentally solved these problems.With advanced technology,constant water pressure,easy operating,reliable operation.energy saving and high degree of automation,the variable-frequency constant-pressure water supply technology has been widely used in various industries.