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Safety Valve Discharge Pressure And Return Pressure Adjustment
Dec 27, 2018

  Safety valve discharge pressure and return pressure adjustment

  1. Adjusting the valve discharge pressure and the return pressure must perform the action test of the valve to the full opening height. Therefore, it is only possible after the large-capacity test device or after the safety valve is installed on the protected device. The adjustment method varies depending on the valve structure.

  2. For the structure with the recoil disc and the seat adjusting ring, the valve seat adjusting ring is used for adjustment. Unscrew the adjusting ring fixing screw and extend a tool such as a thin iron rod from the exposed screw hole to push the gear teeth on the adjusting ring to make the adjusting ring rotate left and right. When the adjustment ring is rotated counterclockwise to the left, its position is raised, and the discharge pressure and the return pressure are reduced.

  Conversely, when the adjustment ring is rotated clockwise to the right, its position is lowered, and the discharge pressure and the return pressure are increased. For each adjustment, adjust: the amplitude of the rotation of the circle should not be too large (generally rotate a few teeth). After each adjustment, the fixing screws should be screwed so that the end is located in the groove between the two teeth of the adjusting ring, which can prevent the adjusting ring from rotating and does not generate radial pressure on the adjusting ring. For safety reasons, the safety valve inlet pressure should be appropriately reduced (generally less than 90% of the opening pressure) before the adjustment ring is turned to prevent the valve from suddenly opening during the adjustment, resulting in an accident.

  3. For the structure with the upper and lower adjustment rings (the guide sleeve and the valve seat have one adjustment ring), the adjustment is more complicated. The seat adjustment ring is used to change the size of the passage between the valve flap and the adjustment ring, thereby changing the amount of pressure accumulated in the chamber between the valve flap and the adjustment ring when the valve is initially opened. When the valve seat adjustment ring is raised, the degree of pressure buildup is increased, so that the phase of the valve proportional opening is reduced and the sudden rapid opening is achieved relatively quickly.

  Therefore, raising the seat adjustment ring can reduce the discharge pressure. It should be noted that the seat adjustment ring must not be raised too close to the valve flap. In this way, the leakage at the sealing surface may cause the valve to suddenly open prematurely, but since the medium pressure is not enough to keep the valve flap in the open position, the valve flap is closed again, and the valve jumps. Valve seat adjustment: "The ring is mainly used to reduce the valve ratio, the opening phase and adjust the discharge pressure, and also affect the return pressure.

  The upper adjustment ring is used to change the angle at which the flowing medium is deflected after the lower side of the valve flap is reflected, thereby changing the magnitude of the fluid force, thereby adjusting the return pressure. When the upper adjustment ring is raised, the folding angle is reduced, and the fluid force is reduced, thereby increasing the return pressure. Conversely, when the upper adjustment ring is lowered, the return pressure is lowered. Of course, while the upper adjustment ring changes the pressure of the seat back, it also affects the discharge pressure, that is, raising the upper adjustment ring causes the discharge pressure to increase, and lowering the upper adjustment ring to reduce the discharge pressure, but the degree of influence is not as good as The seat pressure is as obvious.