Efficient and reliable airborne leak detection
of gas pipelines using CHARM®
CHARM® (CH4 Airborne Remote Monitor) is a new laser-based technology for monitoring gas transmission pipelines, for measuring the quantity of escaping gas from e.g. biogas facilities and for inspecting large surface areas such as landfills from the air.
CHARM® emits two laser pulses of different wavelengths. The two laser pulses are tuned in a way that the first pulse is specifically absorbed by methane while the second wavelength is not. The difference between the light scattered back to the system by both laser pulses is a measure for methane concentration.
Gas concentrations on the ground are measured in ppm (parts per million), airborne gas detection is measured in ppm*m (parts per million * meter).
With the aid of a movable scanning head, the measuring beam always follows the course of the pipeline precisely, even if the helicopter deviates from it horizontally.
It comprises the technical rules and regulations of the German Association of Gas and Water (Deutsche Vereinigung des Gas- und Wasserfachs) for the inspection of high-pressure pipelines. The core conditions for approval pursuant to the DVGW guideline are reliable gas measurements of certain quantities under clearly defined conditions and sufficient coverage of the pipeline with measuring points.
The detection limit of the system is a measure for the system’s sensitivity but does not mean that a certain emission can be detected under any condition.
Determined by standardized field tests. The detectable gas emission is expressed in l/h. This is the verifiable actual volumetric flow of the gas.
A measurement that falls above the alarm threshold but is not an indication of an increased methane concentration.
A measurement that falls below the alarm threshold but is an indication of an increased methane concentration and is therefore a potential source of danger.