Measurement of methane gas concentration using an infrared LED

This paper describes a simple method to measure methane (CH₄ ) gas concentration using an infrared LED (wavelength=1.6 mum). Recently, CH₄ based natural gas is increasingly being used for city gas. However, CH₄ gas is hazardous to gas explosion, so that accurate and convenient concentration sensors of CH₄ are required. We have developed an infrared absorption system for measurement of CH₄ gas concentration. Our method is simpler and more user-friendly than existing measurement methods. The gas concentration is associated with the absorption, the optical path length and the absorption intensity. CH₄ molecule has absorption bands in the infrared region (near 1.3 mum, 1.6 mum, 3.3 mum and 7.6 mum) and the infrared LED can access the CH₄ absorption band in the wavelength region of 1.6 mum. For the purpose of development of concentration sensor of CH₄ gas, examination about the sensing property of absorption of CH₄ by the difference of its concentration is performed, and it reports briefly