Venturi Torch Vacuum Valve for Oxy-Fuel Leak Prevention
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Solution Overview
Problem
Oxy-fuel welding and cutting systems face safety hazards due to flammable and explosive fuel gases like acetylene, with risks of leaks, explosions, and inadequate leak detection in confined spaces, and existing systems lack a defined negative pressure to ensure safe operation.
Innovation Solution
An oxy-fuel system with a vacuum-controlled demand valve and a cutting torch that generates a negative pressure of at least −0.3 bar relative to atmospheric pressure, ensuring the demand valve only opens when sufficient negative pressure is achieved, thereby preventing gas leaks and enhancing safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional demand valve is used in the fuel gas supply line, then the system can supply fuel gas to the torch, but the system lacks safety protection against gas leaks and backflow
Solution Approach 1:
The patent replaces conventional mechanical demand valve control with vacuum-based control. The demand valve is controlled by vacuum pressure differential rather than pure mechanical actuation, where the valve opens when vacuum pressure exceeds a threshold and closes when vacuum is lost, providing automatic safety protection against leaks and backflow
Solution Approach 2:
The system implements feedback control where the state of the fuel line (vacuum or positive pressure) automatically controls the demand valve position. When vacuum is present, the valve opens to allow fuel flow; when positive pressure or leak occurs, the valve closes, creating a self-regulating safety mechanism
2Measurement precision
If leak detection spray is applied to check for leaks in hoses and connections, then leaks can be detected, but the process is time-consuming and user-unfriendly especially for long hoses
Solution Approach 1:
The patent extracts the leak detection function from manual spray application and integrates it into the system operation itself. The vacuum-controlled demand valve continuously monitors for leaks by detecting pressure differential changes, eliminating the need for separate manual leak detection procedures
Solution Approach 2:
The system performs self-diagnosis for leaks through the vacuum control mechanism. The demand valve automatically detects and responds to leaks by monitoring vacuum pressure, making the system self-monitoring without requiring external inspection tools or procedures
3Reliability
If ordinary check valves are used to prevent backflow, then gas flow direction can be controlled, but they cannot stop flashback or detonation waves
Solution Approach 1:
The patent inverts the conventional approach by using vacuum pressure to control valve opening rather than positive pressure. The demand valve closes when positive pressure or flashback occurs, and opens only when vacuum is established, providing protection against both backflow and flashback simultaneously
Solution Approach 2:
The system applies preliminary anti-action by maintaining vacuum pressure in the fuel line to keep the demand valve closed until vacuum is confirmed. This pre-established vacuum condition prevents flashback and detonation waves from propagating back into the fuel supply system
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 system effectively prevents gas leaks and ensures safe operation by maintaining a defined negative pressure, reducing the risk of explosions and improving safety in hazardous environments.
Implementation Method 1
the torch comprises a venturi nozzle adapted to generate in the upstream fuel gas supply line a negative pressure Pnegative of at least −0.3 bar relative to atmospheric pressure
Data Source
AI summary
An oxy-fuel system for supplying a torch with a fuel gas stored under pressure in a container includes the following components: (a) an upstream fuel gas supply line between the container and the torch; (b) a demand valve arranged in the upstream fuel gas supply line; (c) the torch connected to an oxygen supply line. The torch includes a venturi nozzle adapted to generate in the upstream fuel gas supply line a negative pressure Pnegative of at least −0.3 bar relative to atmospheric pressure in operating condition, and the demand valve is vacuum-controlled and configured to have a pressure setpoint to open the demand valve, the pressure setpoint being negative relative to atmospheric pressure and equal or less negative than Pnegative.