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Issue Date: August 23, 1999
Revision Date: December
21, 2005
Varec, Inc.
(originally
listed as Coggins Systems, Inc. and later as Endress + Hauser Systems and
Gauging)
FuelsManager
with Barton Series 3500 ATG (48 hour test) (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 6,082 ft², leak rate is 2.0 gph with PD = 97.8% and
PFA = 2.2% for 48 hour test and PD = 98.5% and PFA = 1.5% for 72 hour
test.
For other tank sizes, leak rate equals [(PSA in ft² ÷ 6,082 ft²) x 2.0
gph].
Example:
For a tank with PSA = 10,000 ft²; leak rate = [(10,000 ft² ÷ 6,082
ft²) x 2.0 gph] = 3.29 gph.
Calculated minimum detectable leak rate is 1.59 gph with PD = 95% and PFA
= 5% for 48 hour test and 1.44 gph with PD = 95% and PFA = 5% for 72 hour
test.
Leak rate may not be scaled below 0.2 gph. |
| Leak
Threshold |
Leak threshold is
proportional to product surface area (PSA).
For tanks with PSA of 6,082 ft², leak threshold is 1.0 gph. For other
tank sizes, leak threshold equals [(PSA in ft² ÷ 6,082 ft²) x 1.0
gph].
Example:
For a tank with PSA = 10,000 ft²; leak threshold = [(10,000 ft² ÷ 6,082
ft²) x 1.0 gph] = 1.64 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, diesel,
aviation fuel. |
| Tank
Capacity |
Use limited to
single field-constructed vertical tanks 50,000 gallons or greater.
Maximum product surface area (PSA) is 15,205 ft². Performance not
sensitive to product level. |
| Waiting
Time |
Minimum of 12
hours, 20 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 7.3 to 17.2 hours. |
| Test
Period |
Minimum of 48
hours (48 hour test). Minimum of 72 hours (72 hour test).
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 |
The differential
pressure sensor must be checked regularly and, if necessary, calibrated 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 600,000 gallon, vertical underground tank with
product surface area (PSA) of 6,082 ft². |
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Varec, Inc.
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Evaluator:
Ken Wilcox Associates
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5834 Peachtree Corners East
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Tel: (816) 443-2494
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Norcross, GA 30092
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Date of Evaluation:
05/20/98
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Tel: (770) 447-9202
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