Propellant Gas Detection via Laser Amplitude Comparison
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Solution Overview
Problem
Current methods for detecting propellant gases in containers, such as aerosol cans, are either costly, labor-intensive, or limited in throughput, and often suffer from human error and contamination issues, particularly in leak testing processes.
Innovation Solution
A method utilizing test and reference laser light pulses in the 3.30-3.55 µm spectrum range to detect propellant gases by comparing the amplitude of pulses passing through a sample chamber with those bypassing it, allowing for accurate detection of propane, n-butane, and other common propellants without the need for complex spectral analysis or multiple detectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If flame ionisation detection is used for propellant gas detection, then detection capability is achieved, but testing rate is limited to 50-100 containers per minute and multiple costly detectors are required
Solution Approach 1:
The patent replaces the flame ionisation detection system with an optical detection system using a laser beam and detector. This substitution enables much higher testing rates (up to 600 containers per minute) while maintaining detection capability, as the optical system has no moving parts and can operate at high speeds without the mechanical limitations of flame-based systems.
Solution Approach 2:
The patent changes the detection parameter from electrical signal measurement in flame ionisation to optical absorption measurement. By using a laser beam at specific wavelengths and measuring light absorption by the propellant gas, the system achieves both high detection precision and high testing throughput with a single detector.
2Measurement precision
If quantum cascade lasers with frequency analysis are used, then propellant detection is achieved, but computing power requirements are significant due to spectral analysis complexity
Solution Approach 1:
The patent extracts only the essential detection function from complex spectral analysis. Instead of performing full spectrum analysis to identify propellant types, the system uses a laser beam at specific predetermined wavelengths where propellant gases have characteristic absorption. This allows detection of propellant presence and leak rates without the computational burden of identifying specific propellant compositions.
3Reliability
If water bath method is used for leak testing, then leakage detection is achieved, but equipment cost, energy consumption, and labour requirements are extremely high
Solution Approach 1:
The patent replaces the mechanical water bath system with an optical detection system. Instead of using a large water bath at 50°C requiring manual monitoring, the system uses a laser beam and detector to automatically sense propellant gas leaks. This substitution dramatically reduces equipment cost, eliminates energy-intensive water heating, and removes the need for manual labour while maintaining reliable leak detection.
4Measurement precision
If optical path length is increased to improve detection sensitivity, then measurement precision improves, but device complexity and cost increase
Solution Approach 1:
The patent uses a multipass optical cell design where the laser beam reflects multiple times between mirrors within a compact cell structure. This nesting of optical paths allows the beam to traverse an extended effective path length (e.g., 100 meters) within a small physical volume, enhancing detection sensitivity without increasing the overall device size or complexity.
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 approach enables faster, more accurate, and economically viable propellant gas detection, capable of high-throughput leak testing with reduced contamination and operational complexity, achieving rates of up to 600 containers per minute with improved precision.
Implementation Method 1
passing a laser beam through a sample chamber and detecting light in the laser beam that has been absorbed by propellant gas in the sample chamber
Implementation Method 2
detecting light in the laser beam that has been absorbed by propellant gas
Data Source
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AI summary
The invention relates to a method and a system for detecting the presence of propellant gas in a gaseous sample exploiting laser light especially in the 3.30-3.5 µm range. The propellant can be propane, n-butane, i- butane, dimethyl ether, methyl ethyl ether, HFA 134a, HFA 227, or any other propellant exhibiting absorption in the requisite wavelength range. The presence of said propellant is detected by comparing the amplitude of test light pulses with the amplitude of reference light pulses. The invention further relates to an application of this method in leak testing of propellant-containing containers such as aerosols or fuel canisters, permitting high-speed, high accuracy leak detection capable of replacing existing testing methods.