Quasi-distributed region selectable gas sensing for long distance pipeline maintenance

In this work, a novel optical gas tele-monitoring concept is proposed. By following this concept, we construct a long distance region selectable gas sensing system, which can address gases of single and/or different types at multi-locations. This approach is based on optical spectroscopy of selected absorption lines of gas leakage. A gas line spectrum can be addressed from a long distance monitoring center using optical fiber, gas sensing region and region selector. The region selecting technique monitors the selected gas absorption and identifies the location of it simultaneously. The technique has potential to be applied to long distance lightweight fiber optic wide-region gas sensing. A multi-region tele-monitoring experiment using FBG monitor as spectroscopy unit, long propagation fibers, gas cells as leakage sensing regions and FBGs as region selectors is demonstrated. Available numbers and coverage of multi-sensing regions are estimated using loss of sensing unit and propagation. (paper)