Bi-Directional Shear Seal Relief Valve for Vent Overpressure
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Solution Overview
Problem
Relief valves experience sealing integrity loss due to undesirable lifting of the shear seal element from the seal plate, caused by overpressure conditions in the vent line, leading to potential failure and difficulty in monitoring the valve's opening pressure in situ.
Innovation Solution
A relief valve design featuring a bi-directional seal between the shear seal element and its bore, with a user-settable bias spring and an annular pressure-leveraging face, along with a check valve and pumping port mechanism for in-situ pressure checking and calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uni-directional seal is used with inlet pressure biasing the seal face against the seal plate, then sealing is maintained during normal operation, but sealing integrity is lost when vent line overpressure occurs
Solution Approach 1:
The patent applies inversion by switching from a uni-directional seal configuration to a bi-directional seal configuration. The bi-directional seal can maintain sealing integrity regardless of pressure direction, preventing seal lift-off during vent line overpressure conditions while maintaining normal sealing function during operation.
Solution Approach 2:
The patent changes the pressure resistance parameter of the seal by transitioning from a seal designed for uni-directional pressure to a bi-directional seal capable of withstanding pressure from either direction. This parameter change enables the seal to adapt to varying pressure conditions without losing sealing integrity.
2Stress or pressure
If the shear seal element is allowed to retract under overpressure, then vent pressure is reduced, but sealing integrity is lost and valve failure occurs
Solution Approach 1:
The patent applies preliminary anti-action by using the bi-directional seal to prevent seal lift-off before overpressure conditions can cause valve failure. The seal is designed to resist pressure from both directions, counteracting the tendency of the shear seal element to retract and lose sealing integrity during vent line overpressure events.
3Ease of manufacture
If traditional relief valve design is used, then basic pressure relief function is provided, but in-situ opening pressure monitoring is difficult
Solution Approach 1:
The patent introduces an intermediary mechanism (the check valve and pumping port system) that enables indirect measurement of the relief valve's opening pressure. By using a separate check valve to trap and hold pressure, and a pumping port to apply controlled pressure, the opening pressure can be monitored in-situ without modifying the basic relief valve design.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The bi-directional seal maintains sealing integrity even under overpressure conditions, and the in-situ pressure checking mechanism allows for proper calibration of the valve's opening pressure, ensuring reliable operation and easy adjustment.
Implementation Method 1
a bias spring present within the piston and configured to bias the shear seal element against the seal plate
Implementation Method 2
a seal element surrounding a body of the shear seal element and in contact with the annular pressure-leveraging face of the shear seal element, the seal element extending between the body of the shear seal element and the inner circumferential surface of the cross bore to seal the inlet side pressure from the vent side pressure
Implementation Method 3
a pumping port through the body of the relief valve and extending from an exterior of the relief valve into the interior volume of the relief valve
Data Source
AI summary
A pressure relief valve includes a valve body including a monitored pressure inlet leading to a monitored pressure region, a piston having a shear seal bore and a surface facing the monitored pressure region, a vent passage and a the shear seal assembly comprising a seal plate having a sealing surface thereon, and the shear seal assembly includes a sealing surface facing the seal plate and having a first annular area, and a first surface having an annular surface area at least twice as large as the first area of the sealing surface, the first surface facing away from the first area, and a biasing seal in contact with the first surface.