Issue Date: September 1, 2023
Think Tank Petroleum Service, LLC
Think Tank - Tank Tightness Tester
NON-VOLUMETRIC TANK TIGHTNESS TEST METHOD (VACUUM)
Leak rate of 0.1 gph with PD = 100% and PFA = 0%.
A tank system should not be declared tight when the acoustic signal detected is different from the baseline signal before a vacuum is placed on the tank, or when water ingress is detected by the water sensor.
Gasoline, diesel, aviation fuel, fuel oil #4, fuel oil #6, solvents, and
of 30,000 gallons.
None between delivery and testing.
groundwater level in tank excavation backfill is below bottom of tank:
Pressure differential across tank wall at bottom of tank must be at least 1 psi or up to 3.7 psi. Pressure differential across tank wall is equal to the absolute value of vacuum applied to tank, plus groundwater pressure on tank, minus pressure of liquid in tank.
Acoustic signal is independent of product temperature.
Conductivity water sensor must be used to detect water ingress and must be
calibrated for every test when groundwater level in tank excavation backfill
is above bottom of tank or when the groundwater level in the tank excavation
backfill has not been determined.
Groundwater level in
tank excavation backfill must be determined by observation well or soil
probe in tank excavation backfill.
If groundwater level in tank excavation backfill is above bottom of tank or the groundwater level in the tank excavation backfill has not been determined, water sensor must be used and test time extended to ensure water ingress detection during test.
Method should not be used to test tanks containing fuel higher than a 10% ethanol content if the water table is above bottom of the tank.
Microphone was 25 ft
away from leak source during evaluation.
*Although not evaluated on empty tanks a third-party acoustics specialist has certified that the measured acoustic signal of a 0.1 gph leak would be detected in an empty tank.
Test may be inconclusive if there is high background noise.
Vacuum test method may not be effective in some tank excavation backfill (such as clay) because it may plug holes in tank.
If free product is present in tank excavation backfill, a leak in the free product zone may not be detected by a vacuum test method.
An observation well or soil probe in tank excavation backfill may help determine backfill material, water level in tank excavation backfill, and free product.
Requires annual tester certification for operator and equipment by the manufacturer.
Operator hearing test should be within normal range, 0 to 20 decibels for annual exam. More than 4 psi pressure differential across the tank wall at any location in the tank could damage tank.
|Think Tank Petroleum Service, LLC
|Evaluator: Ken Wilcox Associates
|P.O. Box 1729
|Tel: (816) 443-2494
|Travelers Rest, SC 29690
|Date of Evaluation: 02/10/2023
|Tel: (864) 370-0637
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this list is not to be construed as an endorsement by any regulatory agency nor
is it any guarantee of the performance of the method or equipment.
Equipment should be installed and operated in accordance with all applicable laws and regulations. For full details, please refer to our expanded "DISCLAIMER" page.