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Pipe fitting precision casting process

Edit:Xiangyang Liqiang Machinery Co., Ltd.UpDate:2019-06-10

       Pipe fittings >What are the standards for accessories?

       The main problem with valve closure is how to achieve a complete seat clearance for closing the valve. A common method of sypv is to align the valve so that the closing parts (such as valve plugs, diaphragms, valve plates, etc.) are on the seat, rather than confirming that the bonnet rests completely against the seat. In order to maintain design leakage and avoid corrosion of the sealing surface, an appropriate sealing load must be designed.


       Single-acting pneumatic actuators are typically designed as thin films in valve tube casting. This design uses the design of the spring, which reduces the seat load and can withstand the full closing pressure. It is a very typical double-acting pneumatic actuator with a piston design. With this design, unlike the membrane design, the supply pressure does not need to be limited. In order to achieve a higher closing pressure, the full supply pressure can be applied. For the piston design, the higher the pressure, the better the stability and control sensitivity of the valve.

       Many designers usually Use a 4-20 mA signal as the information signal instead of the power signal. For membrane actuators, the power signal not only determines the position of the closing component, but also drives the working air supply and closes the valve. When the valve is calibrated, the signal value is exactly 4 mA when the valve is closed. To ensure that no seat loads are generated, the auxiliary power supply is applied to the valve design.

       valve fittings fittings is only produced when the control signal drops below 4 mA, but this signal is usually not present in the control system. Therefore, the purpose of discussing this issue is simply to calibrate the valve to close accurately and tightly. When closed, the seat is fully loaded. When the signal value is 3-5% of the manipulated value, an abnormal calibration is performed to position the valve on the valve seat. Or when the stroke of the valve reaches the preset position, the quick action relay changes the positioner signal to completely close the valve and apply a full load closing pressure.

 

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