Heath Consultants Optical Methane Detector (OM) - Manual (Page 45)

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2. Grade 2(B) - A leak that is recognized as being non-
hazardous at the time of detection but requires
scheduled repair locations are completed.
3. Grade 3(A) - A leak that is non-hazardous at the
time of detection and can be reasonably expected to
remain non-hazardous.
The purpose of classification is to arrange the locations
in order of priority to assist the operator in scheduling,
pinpointing and repair. THE CLASSIFICATION IS A
JUDGEMENT BY THE CONSULTANT BASED ON
THE INFORMATION AVAILABLE TO HIM. It in no
way indicates the condition of the pipe or the size of the
leak in the pipe or the amount of gas leaking on con-
cealed piping.
Any leak indication detected, which, in the judgement
of the consultant, requires immediate attention (Grade
1) should be reported by telephone to the designated of-
ficial when detected unless otherwise instructed by the
client. The time the leak is called in must be noted on
the leak report.
“Each leakage area which is to be classified, must first
be evaluated to determine the extent of gas migration.
Bar holes must be placed and tested with CGI in all di-
rections until zero readings are obtained. When gas has
entered substructures, available openings to affected
substructures must be tested in all directions along that
system until zero readings are obtained.”
V. Factors Which Affect Gas Migration
The success of surface survey greatly depends on the migration
of gas through the soil and atmosphere. The technician must
consider these factors and their effects throughout the survey.
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PPENDIX
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