Issue Date: August 23, 1999
ASTTest Services, Inc.
ASTTest Mass Balance Leak Detection System
Bulk Underground Storage Tank Leak Detection Method (50,000 Gallons Or Greater)
| Certification | Leak rate is proportional to product surface area (PSA). For tank with PSA of 5,575 ft2, leak rate is 0.88 gph with PD = 95% and PFA = 5%. For other tank sizes, leak rate equals [(PSA in ft2 ÷ 5,575 ft2) x 0.88 gph]. Example: For a tank with PSA = 10,000 ft2; leak rate = [(10,000 ft2 ÷ 5,575 ft2) x 0.88 gph] = 1.578 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 5,575 ft2, leak threshold is 0.44 gph.
For other tank sizes, leak threshold equals [(PSA in ft2 ÷ 5,575 ft2) x 0.44 gph].
Example: For a tank with PSA = 10,000 ft2; leak threshold = [(10,000 ft2 ÷ 5,575 ft2) x 0.44 gph] = 0.789 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 | Diesel, aviation fuel, fuel oil, kerosene. 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 13,938 ft2 (approximately 133 ft diameter). Performance not sensitive to product level. |
| Waiting Time | Minimum of 48 hours after delivery or dispensing. Valve leaks and pump drain-back may mask a leak. Allow sufficient waiting time to minimize these effects. There must be no dispensing or delivery during waiting time. |
| Test Period | Minimum of 48 hours. There must be no dispensing or delivery during test. |
| Temperature | Average for product is determined by a minimum of 10 thermistors. |
| Water Sensor | None. Water leaks are measured as changes in level inside tank. |
| Calibration | Level and temperature sensors 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 2,000,000 gallon, vertical aboveground tank with product surface area (PSA) of 5,575 ft2. Tests conducted in a vertical wall underground tank may achieve better results. |
- ASTTest Services, Inc.
2336 Hamlet Drive
Melbourne, FL 32934
Tel: (407) 242-1474 - Evaluator: Albert Machlin, P.E.
Tel: (212) 675-5868
Date of Evaluation: 11/98
Home | Vendors: A–F | Vendors: G–M | Vendors: N–S | Vendors: T–Z | Method Index
Appearance on this list is not to be construed as an endorsement by any regulatory agency nor is it any guarantee of the performance of the method or equipment. Equipment should be installed and operated in accordance with all applicable laws and regulations. For full details, please refer to our expanded DISCLAIMER page.
