Self-reliance type differential pressure control what are the precautions for pneumatic valve selection

pneumatic valve, pressure differential control does not need any external energy, relying on the modulated medium pressure changes automatically adjust itself, automatic eliminate the residual pressure head and pipe network pressure fluctuation caused by the flow changes, a constant user import and export pressure difference, especially suitable for household metering and automatic control system, help the stability of the system is running.
　　（ ） Differential pressure control pneumatic valve and differential pressure of the pneumatic valve pipe network should be matching
pneumatic valve outside the pipe network pressure difference is different, differential pressure control pneumatic valve working characteristic curve is different. So in the design selection and network operation, should guarantee the pneumatic pipe, valve installation points of pipe network pressure difference within the scope of the pneumatic valve allows changes. The actual pressure difference is too big or too small will disable the spring, led to the pneumatic valve cannot work normally.
　　（ ） Selection of pressure difference control pneumatic valve set pressure differential
the differential control pneumatic valve set pressure difference should be and pneumatic valve piping system under the design discharge resistance matching, to ensure that the pneumatic valve in its best working area. Both are too big to pneumatic valve piping system in actual traffic is too large, resulting in the pneumatic valve hydraulic disorder or piping system results in a piping system in the pneumatic valve actual flow affect heating effect is too small.
　　（ ） Selection of pressure difference control of pneumatic valve diameter
different diameter of pressure difference control pneumatic valve control flow range is different. When choosing pneumatic valve, pneumatic valve will be according to the pneumatic valve working characteristic curve within the piping system design flow take work in the best range of pneumatic control valve flow area slants big side is better. Select pneumatic valve diameter is too small, make the pneumatic valve in the control flow range of high-end work, easy to produce noise. Select pneumatic valve diameter is too large, the pneumatic valve in the control flow range of low-end jobs, system flow range is too big, easy cause disorder of outside piping system hydraulic pneumatic valve, at the same time also cause economic waste. Generally in a pneumatic valve pneumatic valve diameter pipeline system interface diameter equal to or better a smaller size.
　　（ ） Differential pressure control pneumatic valve is no substitute for flow control pneumatic valve
using the differential control of pneumatic valve is designed to make user can within a certain range according to the requirements of the heat flow adjusting, using differential pressure control pneumatic valve of heating system is a variable flow system. But at present most of the heating network is set according to the basic need of heating, real hard to do on-demand unlimited heating pipe network system, certainly will cause disorder of hydraulic pipe network system, especially in the installation of pressure difference control pneumatic valve only and did not install the heating system of thermal table, hydraulic disorder phenomenon is particularly serious. In the current from the meet the needs of the basic heating to on-demand heating transition stage, there are two ways to solve the paradox: (1) increasing network traffic; (2) or at the entrance of the thermal limit traffic on the trunk. Limit flow method to set the flow control of pneumatic valve. Flow control pneumatic valve can choose self-help type pneumatic valve flow control, the balance of pipe network can automatically flow. Self-reliance type must be set up in each thermal entrance are flow control pneumatic valve, high cost of this way, so use fewer. Another way is set up on the trunk and self-reliance type flow control pneumatic valve. Currently the vast majority of thermal entrance use lock closed flow control pneumatic valve, this request at the beginning of the pipe network of commissioning work, the initial adjustment must be made by artificial means time-consuming, laborious, the work is relatively complicated, difficult to adapt to the change of working condition of heat supply network. But this is a kind of economy guarantee measures of heating pipe network hydraulic balance.