Quasi-distributed multipoint laser methane detection system and its application in cable trench safety monitoring

A low power consumption, quasi-distributed, multi-point laser methane detection system incorporating a Vertical Cavity Surface Emitting Laser (VCSEL) has been designed and its performance discussed. Being based on the features of the methane absorption spectrum and adaptive tracking technology, the system can realize on-line methane monitoring across 14 channels of sensors, with the maximum transmission distance for each sensor being 10km. Working across a temperature range of 0°C-40°C, the measurement error was determined to be less than ±0.03% (of the gas concentration) when the methane volume concentration lies in the range up to 10% methane. The system has been tested in-the-field in a cable tunnel belonging to a power supply company in Jinan in China and the test results achieved show that the system has the high accuracy and good stability needed for use in industrial safety monitoring