Precautions for selection of self-operated differential pressure control valve
The self-operated differential pressure control valve does not require external energy to automatically adjust itself by relying on the pressure change of the controlled medium, and automatically eliminates the residual pressure head of the pipe network and the flow deviation caused by pressure fluctuations. Especially suitable for household metering or automatic control system.
1. The differential pressure control valve should be matched with the pressure difference of the pipe network outside the valve
Different pressure difference in the pipe network outside the valve, the working characteristic curve of the pressure difference control valve is different. Therefore, in the design selection and actual operation of the pipe network, it should be ensured that the pipe at the installation point of the valve and the pressure difference of the pipe network vary within the allowable range of the valve. The actual pressure difference that is too large or too small will cause the spring to fail, resulting in the valve not working properly.
2. Selection of the set differential pressure of the differential pressure control valve
The set pressure difference of the differential pressure control valve should match the resistance of the pipeline system in the valve under the design flow rate, so as to ensure that the valve works in its optimal working area. If the difference between the two is too large, the actual flow of the pipeline system in the valve will be too large, which will cause the hydraulic imbalance of the pipeline system outside the valve or cause the actual flow of the pipeline system in the valve to be too small, which will affect the heating effect.
3. Selection of the diameter of the differential pressure control valve
Different calibers of differential pressure control valves control different flow ranges. When selecting a valve, it is better to take the design flow of the pipeline system in the valve to the larger side in the better working area of the valve control flow range according to the valve working characteristic curve. If the valve diameter is too small, so that the valve works at the high end of its control flow range, it is easy to generate noise. If the valve diameter is too large, the valve will work at the low end of its control flow range, and the system flow change range is too large, which will easily cause hydraulic imbalance in the piping system outside the valve, and also cause economic waste. Generally, the diameter of the valve is equal to or one size smaller than that of the pipe system interface in the valve.
Fourth, the differential pressure control valve can not replace the flow control valve
The purpose of using the differential pressure control valve is to enable the heat user to adjust the flow according to the heat demand within a certain range. The heating system using the differential pressure control valve is a variable flow system. However, at present, most of the heating pipe networks are determined according to the basic needs of heating, and it is difficult for the pipe network system to supply unrestricted heating on demand, which will inevitably cause the hydraulic imbalance of the pipe network system, especially when only the differential pressure control valve is installed without the In the heating system equipped with heat meter, the phenomenon of hydraulic imbalance is particularly serious. In the current transitional stage from meeting basic heating needs to on-demand heating, there are two ways to solve this contradiction: (1) increase the flow of the pipe network; (2) limit the flow at the thermal inlet or on the branch lines. The method to restrict the flow is to set the flow control valve. The flow control valve can choose a self-operated flow control valve, so that the pipe network can automatically balance the flow. A self-operated flow control valve is installed at each thermal inlet, which is more expensive and therefore less used. Another way is to set up a self-operated flow control valve on the branch line. At present, most of the thermal inlets use locking flow control valves, which requires that the initial adjustment work must be done manually in the early stage of the operation of the pipeline network. This work is time-consuming, laborious, complex, and difficult to adapt to the working conditions of the thermal network. Variety. But this is an economical measure to ensure the hydraulic balance of the heating network.
The above four points are the precautions for the selection of self-operated differential pressure control valve shared with you today. If you are helpful, please collect and forward it~