Actuator Partial Stroke Test Mechanical Stop
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Solution Overview
Problem
Safety valves in safety-oriented industries, such as chemical and power generation, can close too far during partial stroke testing, leading to unintended disturbances or hazardous situations due to excessive friction or blockages, which existing methods fail to prevent.
Innovation Solution
A mechanical stop, designed as a movable cam, is introduced to limit the actuating path of the valve, and a continuous pressure increase is used to overcome friction, allowing the valve to move within safe limits during testing, with error detection and pressure reduction mechanisms to prevent over-travel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the partial stroke test method is used to test safety valve functionality, then the valve can be checked for proper operation, but the valve may close too far due to the break-loose effect, causing unintended disturbances or hazardous situations
Solution Approach 1:
A mechanical stop is pre-positioned in the actuating path to limit the maximum travel distance of the actuator before the break-loose effect can cause dangerous over-closing. This preliminary physical constraint prevents the harmful outcome before it can occur.
Solution Approach 2:
The mechanical stop acts as an intermediary element between the actuator and the valve closure process, physically interrupting the actuating path to prevent excessive travel. This intermediary component absorbs the excess energy and prevents direct harmful contact or over-closing.
2Object-affected harmful factors
If a mechanical stop is introduced to limit the actuating path, then the valve cannot close too far, but the device complexity increases
Solution Approach 1:
The mechanical stop is designed as a simple, inexpensive component that can be easily installed and replaced if needed. Rather than using a complex electronic control system with sensors and actuators, a basic mechanical latch provides the necessary function at minimal cost and complexity.
Solution Approach 2:
The essential function of limiting valve travel is extracted from the complex electronic control system and implemented through a separate, simple mechanical stop device. This separates the safety function from the main actuating system, reducing overall complexity while maintaining the critical protection function.
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 solution prevents the valve from closing too far during testing, ensuring safe operation and allowing for accurate detection of malfunctions without manual intervention, thereby avoiding hazardous states and ensuring reliable functionality.
Implementation Method 1
A mechanical stop, designed as a movable cam, is introduced to limit the actuating path of the valve
Implementation Method 2
a continuous pressure increase is used to overcome friction, allowing the valve to move within safe limits during testing
Data Source
AI summary
In a method for testing the functionality of an actuator in an actuating system, especially for the actuator of a valve (2) in a safety-oriented circuit in which the partial stroke test method is used, where the actuator is moved briefly by its drive element (8) such as a valve rod over a portion of its actuating path to test its functionality, the goal is to prevent the actuating system from closing too far during the performance of the partial stroke test method. This is accomplished in that, to prevent the actuating system from closing too far, the drive element (8) with the actuator is driven in such a way that it can be moved only within permitted limits during the partial stroke test. The actuating path of the actuator (7, 8) is limited by a mechanical stop (15). The pressure in the drive of the actuator (8) can also be increased continuously until the friction of the system is overcome, where a conclusion concerning the status of the actuating system can be drawn on the basis of the pressure value at which the actuator (8) starts to move.