When the pressure differential between the inlet and outlet of the main valve changes, the pressure differential between pipe A and pipe B also changes, thereby altering the opening of the pilot valve. A larger pressure differential results in a larger opening of the pilot valve. This increases the amount of water drained from the control chamber through pipe C, causing the pressure in the main valve control chamber to decrease. Consequently, the main valve opens further, reducing the pressure differential between its inlet and outlet. Conversely, if the pressure differential between the main valve inlet and outlet decreases, the pilot valve opening reduces. This increases pressure in the main valve control chamber, pushing the main valve to close further and thereby increasing the pressure differential. This negative feedback action stabilizes the pressure differential between the main valve inlet and outlet at a set value. The pressure differential can be adjusted by setting the needle valve opening and the pilot valve spring pressure.
| Nominal Pressure(Mpa) | Shell Test Pressure(MPa) | Seal Test Pressure(MPa) | Applicable medium | Medium temperature(℃) |
|---|---|---|---|---|
| 1.0 | 1.5 | 1.1 | Water | 0~80(Diaphragm-type) 0~200(Piston-type) |
| 1.6 | 1.76 | 2.4 | ||
| 2.5 | 2.75 | 3.75 |
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