Abstract:

In order to elucidate the specific causes of abnormal alarms from CH₄ and CO sensors in the return corner of the backfill working face, a systematic investigation was conducted. Initially, a programmed heating-gas chromatography (GC) experiment was carried out on filling materials, complemented by on-site GC measurements, to evaluate whether the alarms were attributable to CH₄ and CO concentrations exceeding threshold limits. Subsequently, a portable gas detector was employed to monitor various filling materials, identifying the primary materials responsible for triggering the sensor alarms. Finally, GC-mass spectrometry (MS) analysis was performed to characterize the volatile components of adhesives and their interference effects on CH₄ and CO sensors. The results indicate that the alarms triggered by CH₄ and CO sensors were caused by the volatile gases from adhesives, rather than by an excessive concentration of CH₄ or CO. The primary constituents of the adhesive VOCs were alkanes, while secondary components included alcohols and esters. Key interfering substances for CH₄ sensor were alkanes such as C₅H₁₂, C₆H₁₂, and C₆H₁₄, with minor contributions from alcohols and esters such as CH₄O, C₂H₄O₂, and C₃H₈O₂. All ten tested combustible gases exhibited cross-interference effects on CH₄ sensor. Interfering substances for CO sensor included CH₄O, C₂H₄O₂, and C₃H₈O₂. While the sensors demonstrated short-term resilience to interference under abnormal gas atmospheres, their stability and anti-interference performance significantly deteriorated with prolonged exposure.

Key words: backfill working face, abnormal gases, sensors, cross-interference, return corner, abnormal alarms, adhesives