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Issue Date: November 22,
1995
Revision Date: October 5, 2010
Containment
Solutions, Inc.
(originally listed as
Fluid Containment and O/C Tanks)
Hydrostatic
Precision Tank Test for DWT-Type II Tanks
INTERSTITIAL
TANK TIGHTNESS TEST METHOD
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Certification
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Leak
rate of 0.1 gph with PD = 99.9% and PFA = 1.2% without
dispensing.
Leak rate of 0.1 gph with PD = 95% and PFA = 5.0% with
dispensing.
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Leak
Threshold
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0.05
gph without dispensing and 0.07 gph with dispensing.
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, motor oil, biodiesel blends B6-B20 meeting ASTM D7467, biodiesel B100 meeting ASTM D6751*.
Other liquids with known coefficients of expansion and density may be tested after consultation with the manufacturer.
*NWGLDE Listings apply to leak detection functionality only and not material compatibility - see "Disclaimer".
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Tank
Capacity
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Maximum
of 30,000 gallons.
Tank must be between 0 and 100% full. Maximum tank diameter
is 10 feet.
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Waiting
Time
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Minimum
of 24 hours between delivery and testing.
Minimum of 3 hours between "topping off" the
annular space with liquid and testing.
There must be no delivery during waiting time.
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Test
Period
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Minimum
of 4 hours.
A leak is not declared unless the threshold is exceeded
in two tests, separated by at least 8 hours which are
performed without dispensing and with minimal changes
in groundwater elevation above bottom of tank as described
below.
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Other
Limitations
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Volume
of trapped vapor must not exceed 20 gallons.
Change in barometric pressure must be less than 0.04 psia
over the 4-hour test period.
Annular space must be at least 100% full with either water
or antifreeze.
If groundwater is above bottom of tank, and no product
is being dispensed during test, total change in groundwater
elevation during test must be less than 1.5 inches per
hour.
If groundwater is below bottom of tank or not changing
during test, total change in product level during test
must be less than 0.75 inch per hour.
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Containment Solutions, Inc.
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Evaluator: Vista Research
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5150 Jefferson Chemical
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Tel: (415) 966-1171
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Conroe, TX 77301-6834
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Date of Evaluation: 05/15/91
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Tel: (800) 628-2657
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Web
Address: www.containmentsolutions.com
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