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Issue
Date: August 23, 1999
Steel
Tank Institute
Permatank
Interstitial Vacuum Monitor Liquid Leaks
CONTINUOUS
INTERSTITIAL TANK SYSTEM MONITORING METHOD (PRESSURE/VACUUM)
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Certification
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Leak
rate of 0.1 gph with PD = 100% and PFA < 5%.
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Leak
Threshold
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A
tank system should not be declared tight when the vacuum
decreases (pressure increases) 5 inches or more of mercury
over the test period specified for each tank size.
Vacuum prior to test must be minimum of 14 inches of mercury.
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Applicability
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Gasoline,
diesel, water.
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Tank
Capacity
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Maximum
of 20,000 gallons. No minimum product level during test.
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Waiting
Time
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None
between delivery and testing.
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Test
Period
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Test
periods required for selected tank sizes to detect a leak
rate of 0.1 gph
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Selected
Tank Sizes
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gasoline
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diesel
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water
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500
gal
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0.4
hr
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5.0
hr
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4.8
hr
|
|
5,000
gal
|
1.3
hr
|
16.2
hr
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15.7
hr
|
|
8,000
gal
|
2.1
hr
|
24.9
hr
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24.2
hr
|
|
20,000
gal
|
3.7
hr
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44.8
hr
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43.6
hr
|
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Comments
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System tests the interstitial
space between inner steel wall and outer fiberglass
wall of Steel Tank Institute's Permatank.
Interstitial space is tested continuously.
System detects breaches in either inner or outer tank
walls.
System was not evaluated for ability to detect layer
of hydrocarbons on water.
Evaluation did not cover any liquid sensors.
This system may not be compatible with all secondarily
contained tanks and/or piping. Always consult with the
tank and/or piping manufacturer and the manufacturer's
applicable recommended installation practices before
installing this system, or damage may be caused to the
tank or piping by its use.
State Waterboard staff are currently evaluating the applicability of this method in satisfying the performance standards for continuous vacuum/pressure monitoring systems required by Assembly Bill 2481 (Chapter 6.7, Health and Safety Code, section 25290.1). Listings will be updated once a determination has been made. |
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Steel
Tank Institute
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Evaluator: Ken Wilcox Associates
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570
Oakwood Rd.
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Tel: (816) 443-2494
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Lake
Zurich, IL 60047
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Date
of Evaluation: 04/24/94
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Tel: (847) 438-8265
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