In the air-conditioning and heating systems, the hydraulic balance of the water circulation system as a transmission and distribution energy is very important. A balanced hydraulic system is to meet the needs of users, saving energy consumption based on the operation. In the air conditioning and heating systems, cold (heat) media from the closed pipe system to the user. For a well-designed pipe network system, each user should be able to obtain the design water volume when the opening of the end control valve (electric control valve, temperature control valve, etc.) is 100%, and each user changes the opening degree of the end control valve When both the required traffic and non-interference. Such a water system is a hydraulic balance system, otherwise it is a hydraulic imbalance system, hydraulic imbalance, also known as hydraulic imbalance. Hydraulic disorders are generally divided into two kinds of static disorders and dynamic disorders. The so-called static imbalance, also known as steady-state disorders. That is, the system, the user in the design state, the actual flow and design flow does not match. This type of hydraulic imbalance is fundamental and, if left unresolved, the effects are always present. For constant flow system, this imbalance can be static balance valve or dynamic balance valve to solve, the difference is that the former need to adjust the instrument, which do not need the latter. The so-called dynamic imbalance, also known as stability disorders. In other words, when the water flow of some users changes (closes or adjusts) in the system, the distribution of the resistance of the system will change and the traffic of other users will change accordingly. This hydraulic imbalance is random and dynamic. This imbalance static balance valve can not be solved, can only be used to solve the dynamic balance valve. For example, if a building is a six-storey building, if the dynamic flow balance valve is not installed, the water system will be dynamically imbalanced in actual operation. In the air conditioning cooling season, the first to second floor rooms will be too cold, three to four rooms just reached the design temperature comfort, five to six rooms are too hot. On the contrary, in the heating season, the first to second floor rooms will be too hot, three to four rooms just reached the design comfort temperature, five to six rooms are too cold. After the installation of dynamic flow balance valve, whether it is a ~ six-story rooms are all used or only part of the room in the use of air conditioning, all rooms can reach the design temperature