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.

 

Varec, Inc.

Evaluator:  Ken Wilcox Associates

5834 Peachtree Corners East

Tel:  (816) 443-2494

Norcross, GA 30092

Date of Evaluation:  05/20/98

Tel:  (770) 447-9202

 

 

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