Also known as static balance valve balance valve, manual balancing valves, digital lock balance valve, double regulating valve, which is by changing the valve and valve seat clearance static balance valve （opening）, to change the resistance to flow through the valve to achieve the purpose of regulating traffic, its role object is a system of resistance, static balance valve can be calculated according to the design of new water equilibrium distribution ratio, each branch while proportionally increase or decrease, still meet the current needs under part load climate traffic demand, play a role in thermal equilibrium.