Issue Date: August 9, 2001 
Revision Date: December 21, 2005

Varec, Inc. 
(originally listed as Coggins Systems, Inc. and later as Endress + Hauser Systems and Gauging)

FuelsManager and Remote Terminal Unit RTU/8130 
(MTS Magnetostrictive Probe)

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 616 ft², leak rate is 0.2 gph with PD = 96.4% and PFA = 3.6% 
For other tank sizes, leak rate equals [(PSA in ft² ÷ 616 ft²) x 0.2 gph]. 
Example:
For a tank with PSA = 900 ft²; leak rate = [(900 ft² ÷ 616 ft²) x 0.2 gph] = 0.29 gph. 
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 616 ft², leak threshold is 0.1 gph.
For other tank sizes, leak threshold equals [(PSA in ft² ÷ 616 ft²) x 0.1 gph].
Example:
For a tank with PSA = 900 ft²; leak threshold = [(900 ft² ÷ 616ft²) x 0.1 gph] = 0.1gph. 
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 924 ft².
Product must be at full operating level.
Waiting Time Minimum of 4 hours, 26 minutes after delivery or dispensing.
Test Period Minimum of 24 hours. 
There must be no dispensing or delivery during test.
Temperature Average for product is determined by a minimum of 5 resistance temperature detectors (RTDs). 
Product temperature change during test should not exceed 0.72 degrees F.
Water Sensor Must be used to detect water ingress. Minimum detectable water level in the tank is 0.238 inch. 
Minimum detectable change in water level is 0.0017 inch.
Calibration Probe must be checked 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. 
FuelsManager uses PC-based software to process probe data. 
Remote Terminal Unit (RTU/8130) contains software embedded in a CPU housed in a stand-alone console.
Evaluated in a nominal 50,000 gallon vertical underground tank with product surface area (PSA) of 616 ft². 
The maximum product level in the tank during test was 65% (32,500 gallons).

 

Varec, Inc.

Evaluator:  Ken Wilcox Associates

5834 Peachtree Corners East

Tel:  (816) 443-2494

Norcross, GA 30092

Date of Evaluation:  11/24/98

Tel:  (770) 447-9202

 

 

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