# Self operated flow control valve

Self operated flow control valve
Ziligong flow control valve is a new type of regulating valve. Compared with the manual regulating valve, its advantage is that it can be adjusted automatically; compared with the electric regulating valve, its advantage is that it does not require external power. The application practice has proved that in the closed water cycle In the system (such as hot water heating system, air conditioning refrigeration system), the correct use of this valve can easily realize the flow distribution of the system; can realize the dynamic balance of the system; can greatly simplify the debugging work of the system; can stabilize the work of the pump status etc. Therefore, self-operated regulating valves have broad application prospects in heating and air-conditioning projects.

Structure and performance
The function of the self-operated flow control valve is to maintain a constant flow through the valve when the pressure difference between the inlet and outlet of the valve changes, so as to maintain the controlled object connected in series (such as a loop, a user, a device, etc., The same below) has a constant flow rate, and there are many names of self-operated flow control valves, such as self-operated flow balance valve, constant flow valve, self-balance valve, dynamic flow balance valve, etc. Various types of self-operated flow control valves have different structures. There are differences, but the working principle is similar.
Structure and working principle
Structurally speaking, the self-operated flow control valve is a double-valve combination, which consists of a manual adjustment valve group and an automatic balance valve group, as shown in Figure 1. The function of the manual adjustment valve group is to set the flow rate, and the function of the automatic balance valve group is to maintain a constant flow rate.
For the manual control valve group, the flow G=P2-P3 where Kv is the flow coefficient of the manual control valve port, and P2-P3 is the pressure difference on both sides of the manual control valve port. The size of Kv depends on the opening degree, the opening degree is fixed, and Kv is a constant, so as long as P2-P3 remains unchanged, the flow rate G remains unchanged. And the constant of P2-P3 is controlled by the automatic balance valve group. For example, if the pressure difference between the inlet and outlet P1-P3 increases, the automatic balance valve group will be closed down through the action of the pressure-sensitive film and the spring, so that P1-P2 will increase, thereby maintaining the constant of P2-P3; otherwise, P1-P3 will decrease, Then the automatic balance valve group is opened larger, so that P1-P2 is reduced, and P2-P3 is kept constant.
Each opening of the manual adjustment valve group corresponds to a flow rate. The relationship between the opening degree and the flow rate is calibrated by the test bench test, and it is equipped with an opening degree display and locking device.

Performance and Features
1. The flow rate can be set according to the design or actual requirements, which can automatically eliminate the pressure difference fluctuation of the system and keep the flow rate unchanged;
2. To overcome the uneven heating and cooling of the system and improve the quality of heating (cooling);
3. Thoroughly solve the contradiction between the large pressure difference at the proximal end and the small pressure difference at the far end;
4. Reduce the circulating water volume of the system and reduce the system resistance;
5. Reduce the design workload and do not need to carry out tedious hydraulic balance calculations on the pipe network;
6. Reduce the difficulty of network adjustment and simplify the complex network adjustment work into simple traffic distribution;
7. Exemption from the flow redistribution work when the heat source of the multi-heat source pipe network is switched;
8. The flow display value is randomly calibrated on the test bench, flow (m3/h).
technical parameter
1. Medium temperature 0-150℃;
2. The working pressure difference is 20-600Kpa.
Six, selection
1. It can be selected according to the equal diameter of the pipe.
2. It can be selected according to the larger flow rate and the flow range of the valve.
7. Installation and commissioning
1. The flow direction of the medium should be consistent with the flow direction arrow of the valve body;
2. After installation, set the flow rate according to the demand of the pipeline in series with it;
3. Check whether the pressure difference at both ends of the valve is within the working pressure difference range;
4. Try to avoid the valve working in a small flow state;
5. There is no blowdown screw on the spring cover, so blowdown should be done regularly.

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