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Certification
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Leak
rate of 0.1 gph with PD = 100% and PFA = 0%.
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Leak
Threshold
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A
tank system should not be declared tight if the ratio
of the ultrasonic signal (when the tank is under pressure
or vacuum) to the background signal (prior to pressurization
or evacuation) equals or exceeds 1.5 for either 12 kHz
or 25 kHz frequency band.
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Applicability
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Gasoline,
diesel, aviation fuel, fuel oil #4, waste oil.
Other liquids may be tested after consultation with the
manufacturer.
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Tank
Capacity
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Maximum
ullage volume is 6,000 gallons.
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Waiting
time
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None
between delivery and testing if test is conducted after
an underfilled tank tightness test.
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Test
Period
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Minimum
of 5 minutes.
Test data are acquired and recorded by system\' computer.
There must be no dispensing or delivery during test.
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Test
Pressure
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Net
pressure of 1.5 psi or vacuum of 1.0 psi must be maintained
in ullage.
Pressure or vacuum must be maintained in the tank with
a loss of less than 0.4 psi.
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Temperature
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Ultrasonic
and background signals are independent of product temperature.
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Groundwater
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Depth
to groundwater in tank excavation backfill must be determined.
If groundwater is present outside ullage, vacuum test
in ullage must not be used.
Pressure test must be conducted using a net pressure of
1.5 psi in the ullage.
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Calibration
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System
must be calibrated before each test.
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Comments
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Manifolded
tank systems must be isolated prior to test.
Evaluated using unleaded gasoline.
Tests only ullage portion of tank.
Product-filled portion of tank must be tested using an
underfill test method.
Vibration due to nearby equipment or dripping condensation
may interfere with test.
Microphone was located 25 feet away from leak source during
evaluation.
Vacuum test method may not be effective in some tank excavation
backfill (such as clay) because it may plug holes in tank.
If soil is saturated with product, air or water ingress
may not be detected by vacuum test. A well point in the
tank excavation backfill may help identify presence of
this condition.
The manufacturer does not support test results if the technician does not hold a current Alert Technologies certification when the test is performed. Recertification is required by the manufacturer every two years.
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