Certification
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Leak
rate of 0.1 gph with PD = 99.99% and PFA = 0.005%.
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Leak
Threshold
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0.05
gph.
A tank system should not be declared tight if the test
result indicates a loss or gain that equals or exceeds
this threshold.
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Applicability
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Gasoline,
diesel, aviation fuel, fuel oil #4.
Other liquids with known coefficients of expansion and
density may be tested after consultation with the manufacturer.
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Tank
Capacity
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Maximum
of 18,000 gallons.
Tank must be between 11 and 95% full.
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Waiting
Time
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Minimum
of 6 hours between delivery and testing.
None between dispensing and testing.
There must be no delivery during waiting time.
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Test
Period
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Minimum
of 3 hours.
Test data are acquired and recorded by system's computer.
Leak rate is calculated from average of subsets of all
collected data.
There must be no dispensing or delivery during test.
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Temperature
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Average
for product is determined by temperature sensor probes.
A minimum 12 inches of product must be present for the
temperature probes to operate properly.
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Groundwater
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Depth
to groundwater in tank excavation backfill must be determined.
If groundwater is above bottom of tank, product level
must be adjusted during test to provide a minimum net
pressure of 1 psi at bottom of tank during test.
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Calibration
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Temperature
probes and floats must be checked for proper operation
prior to each test.
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Comments
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Not
evaluated using manifolded tank systems.
Tests only portion of tank containing product.
As product level is lowered, leak rate in a leaking tank
decreases (due to lower head pressure).
Consistent testing at low levels could allow a leak to
remain undetected.
EPA leak detection regulations require testing of the
portion of the tank system which routinely contains product.
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