400X flow control valve from the main valve, flow control valves, needle valves, pilot valves, ball valves, micro-filter and pressure gauge hydraulic control over the system. Use of hydraulic automatic operation, control and regulation of the main valve opening, so that the flow through the main valve remains unchanged. This product is the use of hydraulic self-control, no other devices and energy, easy maintenance, traffic control and stability. This series of valves are widely used in high-rise buildings, living areas and other water supply system and urban water supply project. 400X flow control valve works when the valve at the inlet end of the water from the water to flow through the needle valve into the main control room, and after the pilot valve, ball valve out of the main control room to the exit, when the main valve is fully open or floating state. Flow regulator valve set the upper part of the main control valve, the main valve can be set to a certain opening. Adjust the opening degree of the needle valve and a pressure regulating pilot valve spring, the opening degree of the main valve can be maintained at the set opening degree, and the pilot valve when the pressure change to be automatically adjusted to maintain constant flow