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Issue: August 23, 1999
Revision Date:
December 29, 2011
Mass
Technology Corp.
Precision Mass
Measurement Systems SIM-1000 and CBU-1000 (72 hour test)
BULK UNDERGROUND STORAGE TANK
LEAK DETECTION METHOD (50,000 gallons or greater)
| Certification |
Leak rate is
proportional to product surface area (PSA).
For tanks with PSA of 14,200 ft², leak rate is 0.638 gph with PD = 95%
and PFA = 5%.
For other tank sizes, leak rate equals [(PSA in ft² ÷ 14,200 ft²) x
0.638 gph].
Example:
For a tank with PSA = 20,000 ft²; leak rate = [(20,000 ft² ÷ 14,200
ft²) x 0.638 gph] = 0.898 gph. |
| Leak
Threshold |
Leak threshold is
proportional to product surface area (PSA).
For tanks with PSA of 14,200 ft², leak threshold is 0.319 gph.
For other tank sizes, leak threshold equals [(PSA in ft² ÷ 14,200 ft²)
x 0.319 gph].
Example:
For a tank with PSA = 20,000 ft²; leak threshold = [(20,000 ft² ÷
14,200 ft²) x 0.319 gph] = 0.449 gph.
A tank system should not be declared tight if the test result indicates a
loss or gain that equals or exceeds the calculated leak threshold. |
| Applicability |
Gasoline, ethanol
blends up through E100, diesel,
aviation fuel, fuel oil #4. |
| Tank
Capacity |
Use limited to
single field-constructed vertical tanks.
Performance not sensitive to product level. |
| Waiting
Time |
Minimum of 1
hour, 6 minutes after delivery or dispensing.
Valve leaks and pump
drain-back may mask a leak.
Allow sufficient waiting time to minimize
these effects.
Waiting times during evaluation ranged from 8 minutes to
42.5 hours. |
| Test
Period |
Minimum of 72
hours.
There must be no dispensing or delivery during test. |
| Temperature |
Measurement not
required by this system. |
| Water
Sensor |
None. Water leaks
are measured as increase in mass inside tank. |
| Calibration |
Differential
pressure sensor must be checked regularly in accordance with
manufacturer's instructions. |
| Comments |
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.
Evaluated
in a nominal 2,000,000 gallon, vertical underground tank with product
surface area (PSA) of 14,200 ft².
Averaging of
multiple test may be used to improve the performance of the system. |
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Mass Technology Corp.
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Evaluator:
Ken Wilcox Associates
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P. O. Box 1578
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Tel: (816) 443-2494
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Kilgore, TX 75663
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Dates of Evaluation:
03/25/98, 05/19/11
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Tel: (903) 986-3564
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E-mail:
info@mtctesting.com |
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URL: www.mtctesting.com |
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