Issue Date: December 5, 2002
Engineering Design Group
EDG XLD 2000 Plus (Revision 1.02) Leak Detection System
(MTS DDA 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 12,074 ft2, leak rate is 1.92 gph with PD = 95% and PFA = 5%. For other tank sizes, leak rate equals [(PSA in ft2 ÷ 12,074 ft2) x 1.92 gph]. Example: For a tank with PSA = 1,260 ft2; leak rate = [(1,260 ft2 ÷ 12,074 ft2) x 1.92 gph] = 0.2 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 12,074 ft2, leak threshold is 0.96 gph For other tank sizes, leak threshold equals [(PSA in ft2 ÷ 12,074 ft2) x 0.96 gph]. Example: For a tank with PSA = 1,260 ft2; leak threshold = [(1,260 ft2 ÷ 12,074 ft2) x 0.96 gph] = 0.1 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-walled tanks having a capacity of 50,000 to 2,100,000 gallons Minimum product surface area (PSA) is 1260 ft2. Maximum product surface area (PSA) is 12,076 ft2. Performance not sensitive to product level. |
| Waiting Time | Minimum of 30 hours, 18 minutes after delivery or transfer. |
| Test Period | Minimum of 40 hours, 12 minutes. There must be no delivery, transfer, or dispensing during test. |
| Temperature | Average for product is determined by five resistance temperature detectors (RTDs) |
| Water Sensor | Must be used to detect water ingress. Minimum detectable water level in the tank is 2.655 inches. For tanks with a PSA of 12,076 ft2 and containing 2.665 inches of water, system takes 52.7 hours to detect a 0.20 gph water ingress rate. |
| Calibration | System 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. Evaluated in nominal 2,100,000 gallon tank with PSA of 12,076 ft2 (124 feet in diameter). If product temperature change exceeds 1.8 degrees F during test, test will abort. |
- Engineering Design Group, Inc.
800 Meridian Tower
5100 E. Skelly Drive
Tulsa, OK 74135
Tel: (918) 628- 7100 - Evaluator: Ken Wilcox Associates
Tel: (816) 443-2494
Date of Evaluation: 11/16/01
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