Valve Partial Stroke Test System with Parallel Control
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Solution Overview
Problem
Existing partial stroke test systems for valves with pneumatic or hydraulic actuators fail to detect malfunctions in solenoid valves and can cause safety issues when emergency closing commands interfere with the test procedure, especially in double-acting cylinders and during control device failures.
Innovation Solution
A partial stroke test system that includes an electrical control device connected in parallel to the solenoid valves, allowing independent control of the valve for total closure or opening, with priority given to emergency commands over the test procedure, and featuring a control device with inputs from limit switches to manage the test process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a partial stroke test system is implemented using existing prior art, then the valve positioning can be tested, but the solenoid valve malfunctions cannot be detected and safety issues occur when emergency commands interfere with the test
Solution Approach 1:
The patent creates a parallel control path that copies the emergency command signal flow. The test control device monitors copies of the control line signals rather than directly interfering with the primary control path, allowing it to detect malfunctions without adding complex intervention mechanisms to the original system.
Solution Approach 2:
The test control device acts as an intermediary that monitors control line signals and can intervene only when necessary. It receives copies of control signals and limit switch signals, processes them, and only activates solenoid valves when the valve is in the open position and no emergency command is detected, thus mediating between test requirements and safety requirements without adding direct complexity to the primary control path.
2Reliability
If the test control device monitors control line signals to detect emergency commands, then safety can be ensured, but the system complexity increases due to additional monitoring requirements
Solution Approach 1:
The test control device is designed to handle multiple functions: it monitors control line signals for emergency commands, processes limit switch signals for position detection, controls solenoid valves for positioning, and manages the partial stroke test sequence. This multi-functionality reduces the need for separate dedicated components for each function, thereby managing system complexity while ensuring safety.
3Ease of operation
If the valve is controlled to total closure or opening independently of the control device, then emergency operations can proceed, but the test procedure may be interrupted
Solution Approach 1:
The system performs preliminary checks before executing test actions. The test control device continuously monitors control line signals to detect emergency commands before initiating test sequences. When an emergency command is detected, the system preemptively prevents test execution or interruption, thus avoiding test procedure delays while maintaining the ability to perform independent emergency control when truly needed.
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
Ensures safe and reliable detection of valve malfunctions and prioritizes emergency operations, preventing interruptions in industrial processes and enhancing safety by allowing continuous control of the valve during emergencies and partial stroke tests.
Implementation Method 1
a pneumatic or hydraulic actuator for the control of the opening and/or closing of the sealing member
Implementation Method 2
a pneumatic or hydraulic actuator for the control of the opening and/or closing of the sealing member
Implementation Method 3
A spring closes the valve in the event of a pressure drop in the pneumatic cylinder
Implementation Method 4
at least one solenoid valve for controlling the actuator
Data Source
Figure 1~2
Figure 3~4
Figure 5a~5c
AI summary
The invention relates to a system for testing the partial travel of a closure member of a valve (Vf). Said system includes: said valve (Vf) having said closure member capable of moving from a closed position to an open position, or vice versa, a pneumatic or hydraulic actuator (At) for controlling the closure member when opened and/or closed, at least one solenoid valve (Ev1, Ev2) for controlling the actuator (At), a limit switch device (Bfc) comprising electrical contacts, said limit switch device sending out signals representing discrete end-of-travel positions of the closure member, and a controller (MPST) including a memory in which instructions for implementing a partial end-of-travel test are recorded. According to the invention, the controller is electrically connected to said at least one solenoid valve (Ev1, Ev2), in parallel with the control line (LC1, LC2) of the control device, so as to allow the valve (Vf) to be controlled, when totally closed or totally open, by the electrical control device, independently of the controller.