Why is the allowable pressure difference of a double seat regulating valve greater than that of a single seat regulating valve

2021-10-23 02:16:18

Appearance diagram of double seat regulating valve

Pneumatic double seat regulating valve

A double seat regulating valve has two valve cores and valve seats, and the medium flows from the inlet through the upper and lower valve seats before converging to the outlet. Due to the presence of two valve cores and valve seats, when the medium flows in, it directly acts on the upper and lower valve cores, and the force of the upper valve core is upward. The force of the lower valve core is downward, although the diameter of the upper valve core is slightly larger than that of the lower valve core (the assembly process determines that the diameters of the upper and lower valve cores are different). But the upper and lower forces are almost equal in magnitude and opposite in direction, canceling out most of each other (referring to the closed state).

Structural diagram

The final force acting on the valve stem is much smaller than that of a single seat regulating valve under the same operating conditions. When configuring the same pneumatic diaphragm actuator, the allowable pressure difference of a double seat regulating valve is much greater than that of a single seat regulating valve, showing a multiple relationship.

At the same time, the dual seat regulating valve has two flow channels, and the flow capacity is much greater than that of a single seat regulating valve.Similarly, the flow rate can be selected with a diameter one gear smaller than that of a single seat regulating valve.

Electric butterfly valve

schematic diagram

A single seat regulating valve has a valve core and a valve seat channel, and all the pressure of the medium acts on the valve core (referring to the closed state). At this point, the imbalance force is significant. It is necessary to carefully calculate the pressure difference when configuring the pneumatic diaphragm actuator, otherwise the single seat regulating valve may not open or close tightly. At the same time, an electrical valve locator should be configured to make the adjustment process more stable and overcome the imbalance force caused by the valve core.

Single seat regulating valve

A single seat regulating valve has a good performance when used under low pressure difference, with only one valve core, providing good sealing performance and low leakage, which is one order of magnitude smaller than a double seat valve. When there is a high pressure difference, a double seat regulating valve can be selected to effectively overcome the imbalance force of the valve core caused by the high pressure difference.

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