Pressure Regulator Flow Limiter for Lever Disconnect Failures
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Solution Overview
Problem
Conventional pressure regulators face challenges in regulating gas flow during failure modes, such as lever disconnect events, leading to uncontrolled flow and the need for oversized relief valves, which increase costs and complexity.
Innovation Solution
The pressure regulator incorporates a stem assembly with primary and secondary control members and a mechanical stop, allowing for adjustable flow regulation. In normal operation, the stem moves between orientations to block or permit flow, while in failure modes, the secondary control member restricts flow, and the mechanical stop limits the stem's movement to prevent excessive flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pressure regulators are used without flow limitation during failure modes, then the regulators can maintain normal pressure control function, but the relief valves must be oversized to handle uncontrolled flow during lever disconnect events, increasing cost and complexity
Solution Approach 1:
The control member is segmented into multiple functional zones: an upstream face for normal pressure control, a downstream face with a flow restriction orifice for failure mode protection, and a stem with mechanical stop features. This segmentation allows different parts of the same component to serve different safety functions, enabling the relief valve to be smaller while maintaining reliability during failures.
Solution Approach 2:
The control member serves multiple functions: it acts as a pressure control element during normal operation, a flow restriction element during failure modes through its downstream orifice, and a mechanical stop element through its interaction with the stem. This multi-functionality eliminates the need for separate oversized relief valve components, reducing overall device complexity while improving failure mode reliability.
2Reliability
If a mechanical stop is added to limit stem movement, then excessive flow during failures is prevented, but the device complexity increases
Solution Approach 1:
The mechanical stop feature is merged into the stem assembly itself rather than being a separate component. The stem includes integrated stop features that interact with the control member, combining the flow limitation function with the existing stem structure. This merging approach provides failure protection while minimizing additional complexity.
Solution Approach 2:
The mechanical stop is pre-configured in the stem assembly to automatically engage and limit stem movement before excessive flow can occur during failure modes. This preliminary action ensures flow restriction is activated immediately upon lever disconnect or control member failure, improving reliability without requiring complex active control systems.
3Reliability
If the control member is designed with dual faces for different operations, then flow can be restricted during failures, but the manufacturing complexity increases
Solution Approach 1:
The control member is segmented into distinct functional faces: an upstream face for normal pressure control and a downstream face with an integrated orifice for failure mode flow restriction. This segmentation allows each face to be optimized for its specific function while maintaining manufacturability through conventional machining processes.
Solution Approach 2:
The control member is designed as a universal component that performs both normal pressure control and failure mode flow restriction functions. The downstream face includes a flow restriction orifice that automatically limits flow during failures, eliminating the need for separate safety components and simplifying the overall manufacturing process.
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
This design reduces the size and cost of relief valves by automatically restricting flow during failures, protecting downstream devices from overpressure and optimizing regulator performance across different operational modes.
Implementation Method 1
the control element arranged to respond to fluid pressure changes to control flow of a process fluid through the orifice
Implementation Method 2
a mechanical stop configured to engage a stop feature to prevent movement of the stem assembly past a third orientation
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
A control assembly (208, 308) can be configured for use with a pressure regulator (100) having a valve body (100) defining a fluid flow path. The control assembly can include a control member (232, 332, 234, 334), a stem (236, 336), and a lever (288, 388), and can be disposed within the pressure regulator to selectively control fluid flow. The control assembly can include a primary control member (232, 332) and a secondary control member (234), or a mechanical stop (334) that can operate to restrict flow along the fluid flow path, including when the stem disconnects from the lever.