Application Note

ETHANE ANALYSIS

Determing if a detected natural gas
leak is true or false
Any methane generated by the decomposition of organic material buried under the ground of old
industrial areas or former landfill sites can give leak alerts. Even naturally occurring swamp gas
from sewers or marchlands is a common reason for getting false gas leak signals. Determing theprecence of ethane helps field personnel avoid acting on false alarms caused by naturally occurring
methane in the ground.

Application

Utility companies undertake regular surveys of their gas
networks to check for leaks. In some conditions, especially
if lower concentrations of gas are found, identifying the typeof gas is crucial in deciding whether to excavate a pipeline
for repair or not. This application note explains how to makean ethane analysis on site and determine if a natural gas
leak is true or false, with help of the IRwin® Methane Leak
Detector from INFICON.

Traditional method
Once a suspected natural gas leak is pinpointed, a common
procedure to distinguish if gas comes from a leaking gas pipeor from any other source of methane, is sampling the gas in abag, send it to an external laboratory and have the chemicalcompounds analyzed. However, this procedure is both time
consuming and costly. Safety measures have to be taken andthe leak treated as a true natural gas leak until the results areavailable, generally after one or two days. The chemical compound the laboratory normally searches for is ethane. They
focus on this since ethane and other heavier hydrocarbons
are not present in near-surface microbial gas like swamp gas,
but are normally a major component of thermogenic gases
like natural gas. The ethane concentration typically varies
between 0.5vol% to 15vol% in natural gas. A sample withpresence of ethane would therefore indicate that the detectedleak originates from a leaking natural gas pipe.

IRwin is a portable methane leak detector with inbuilt gas chromatograph (GC) for easy and fastethane analysis.

How we do it
The specially developed gas chromatograph (GC) and sensor combination allows
near real-time distinction between swamp gas and natural gas to rapidly determine ifthe detected gas comes from a leaking pipe or from other natural gas sources.
Looking for moderate
gas concentration

Gas samples drawn
from the ground with theunique bell probe

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Performing the ethaneanalysis

Gas concentrations analyzed on site to determine
the precence of ethane

Documenting

Results visualized on theinstrument screen, saved
as pdf-file and sharedEthane Analysis with IRwin GC |    Application Note

The solution from INFICON
This analysis could be easily done on site by any operator
using the IRwin Methane Leak Detector from INFICON, with abuilt-in gas chromatograph (G-models). The complete test isfinished within a few minutes after the leak is detected.
When gas has been detected, the precise location of the areawith highest concentration needs to be pinpointed. Using theunique IRwin bell probe, samples can be drawn through almost any road surfacing material, consistently reducing theneed for drilling bar holes and thus saving time.
The gas chromatography analysis can be made on samples
with concentrations as low as 1000 ppm and up to 100 vol%.
The IRwin methane leak detector automatically takes thesample for the analysis, whereas the operator only needs tofollow the step-by-step instructions on the screen of the leakdetector to have the test performed. Another benefit of thebuilt-in gas chromatograph is the ability to detect ethane concentrations down to 0.5 vol%, even within a small sample.
This extraordinary low ethane detection level will assure that
all true leaks are found and classified.
The analysis result is presented as a live graph showing thesensor signal during the complete test sequence. The different gas compounds will be visualized as separate peaks in thegraph and indicated with a symbol for each gas.

Documentation
Results are always presented on the instrument
screen and give a clear indication of what has been
detected:• NG with Ethane detected - indicates a true natural gas leak is found• Methane detected - indicates a source of methane like swamp gas or biomethane• LPG detected - indicates a propane leak with absence or low levels of methane and ethaneThis is typically presented on the screen within 1-2 minutes
from the time of sampling, whereas the complete cycle time,including system purging, is less than 4 minutes.
At the end of the analysis, the operator will be asked to savethe result as a report. The report is downloadable as pdf at
any time and contains all necessary information like date andtime, a map with coordinates of the location, the results andthe graph itself.

Benefits of ethane analysis with IRwin
Cutting costs and unnecessary work is a major driver for all
businesses, including gas leak detection. The IRwin Methane
Leak Detector (SXG and SXGT models) gives operators theability to identify the precence of ethane at any time, in orderto quickly determine if a detected natural gas leak is true orfalse. The main benefits of ethane analysis performed withhelp of IRwin are:Tips!
IRwin features an integrated proprietary IR-sensor
system for methane-specific measurement. The
IR-Ethane analysis can be used as a rapid first indicator prior to the GC analysis.
Needs higher concentration• Needs higher concentration• Needs approx. 3–15 vol% NG• Results in less than 1 minniaa66en1-1 (2309)• On-site analyzing capability• Rapid responses• Reduced costs

For more information   inficon.com

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Due to our continuing program of product improvements, specifications are subject to change witout notice.