UST Programs - LG 113

Mass Technology Corp.

Precision Mass Measurement System (72 hour test)

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 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 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, diesel, aviation fuel, fuel oil #4. Other liquids may be tested after consultation with the manufacturer.
Tank Capacity	Use limited to single field-constructed vertical tanks larger than 50,000 gallons. Maximum product surface area (PSA) is 35,500 ft² (approximately 213 ft diameter). 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.

Mass Technology Corp.
P. O. Box 1578
Kilgore, TX 75663
Tel: (903) 986-3564
E-mail: info@mtctesting.com
URL: www.mtctesting.com

Evaluator: Ken Wilcox Associates
Tel: (816) 443-2494
Date of Evaluation: 07/31/06

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Equipment should be installed and operated in accordance with all applicable laws and regulations.
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