Highly sensitive and fast detection of propane-butane using a 3 μm quantum cascade laser

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Laser Technology

Background:

• Aerosol propellants such as propane and butane are widely used but require sensitive detection methods for safety and quality control.
• Existing detection methods may lack the speed, sensitivity, or specificity required for industrial applications like leak testing.

Purpose of the Study:

• To develop and evaluate a novel mid-infrared (mid-IR) optical analyzer for ultrafast detection of aerosol propellants.
• To demonstrate the instrument's capability for high-speed, high-sensitivity leak detection in industrial settings.

Main Methods:

• Development of a mid-IR optical analyzer utilizing a 3 μm Fabry-Perot quantum cascade laser.
• Spectral matching of the laser emission bandwidth (35 cm⁻¹) to the C-H vibrational band of hydrocarbons for enhanced sensitivity.
• Implementation of a stable, wavelength-scanning-free operation for rapid measurements.
• Evaluation of the instrument's performance using an industrial demonstrator for aerosol can leak testing.

Main Results:

• The optical analyzer achieves high sensitivity and speed, with a precision of 1 part per million (ppm) within a 10 ms measurement time.
• The system is spectrally well-matched to hydrocarbon C-H vibrational bands and is insusceptible to water interference.
• The industrial demonstrator successfully detected leaks as small as 1.2×10⁻⁴ standard liters per minute (slpm) at a rate of 500 cans per minute.
• The instrument's performance complies with international directives for leak testing.

Conclusions:

• The developed mid-IR optical analyzer offers a highly sensitive and rapid solution for detecting aerosol propellants.
• The instrument's capabilities are well-suited for industrial applications, particularly for high-throughput aerosol can leak testing.
• This technology provides a significant advancement in real-time monitoring and quality control for hydrocarbon-based aerosols.