Infrared Methane Gas Alarm Unit

Introduction

Methane gas is the most common of the saturated hydrocarbons present in the atmosphere and occurs in natural gas and gases from oil wells. It is the principal product of organic decay in swamps and marshes, the gas being set free by the action of bacteria. This method of formation in nature has given rise to the name "marsh gas". The natural concentration of methane gas in atmospheric air is approximately 1.7 PPM.

Liquid methane is used in nuclear industry for cooling of neutrons. Sewage sludge which has been fermented by bacteria yields a gas containing about 70 per cent methane and this is used as a liquid fuel. Methane is used for making printers ink and paints. It is also used in rubber industry for making motor tyres etc. Since methane gas forms an explosive mixture with air in the concentration range 5 - 15 percent, it poses an explosion hazard. Therefore, it is imperative to monitor its concentration in the working areas of plants and to give a warning signal whenever the concentration exceeds the safe limit. It is also required to initiate a suitable corrective action for reducing the concentration.

Non Dispersive Infrared (NDIR) methane gas alarm system developed at Trombay, BARC, is based on the absorption of infrared energy by methane gas molecules at their characteristic absorption band. The extent of absorption of the infrared energy by the methane gas molecules in the gas stream is proportional to the amount of methane gas present in the air. Calibration of the monitors is carried out using standard methane gas mixtures prepared in the laboratory.

This technology is under evaluation.

Contact for more information

Head,
Technology Transfer & Collaboration Division,
Bhabha Atomic Research Centre,
Trombay, Mumbai - 400 085
Tel : 091-022-25505337/25593897
Fax : 091-022-25505151
E-mail : headttcd@barc.gov.in