摘要 |
A method and apparatus are described for determining the safety of a gas mixture containing flammable components such as methane together with ethane or other hydrocarbon, together with a diluent gas. The method comprises the filtered infrared spectroscopy of the gas mixture in a gas cell (10) using a filter (16). The peak transmission wavelength (lambdmax) and bandwidth of the filter (16) are so chosen to provide an output, when an infrared light source (42) having a flat wavelength distribution is used, indicative of the %LEL of the gas mixture, within a predetermined tolerance. The filter may be a gas correlation filter containing a mixture of methane and ethane, together with a diluent gas.
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