Issue Date: December 5, 2002
Engineering Design Group
Ronan X-76 CTM Automatic Tank Gauging System
(MTS Level Plus UST 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 564 ft2, leak rate is 0.2 gph with PD > 99.9% and PFA < 0.1%. For other tank sizes, leak rate equals [(PSA in ft2 ÷ 564 ft2) x 0.2 gph]. Example: For a tank with PSA = 846 ft2; leak rate = [(846 ft2 ÷ 564 ft2) x 0.2 gph] = 0.3 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 564 ft2, leak threshold is 0.1 gph. For other tank sizes, leak threshold equals [(PSA in ft2 ÷ 564 ft2) x 0.96 gph]. Example: For a tank with PSA = 846 ft2; leak threshold = [(846 ft2 ÷ 564 ft2) x 0.1 gph] = 0.15 gph. Leak threshold may not be scaled below 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 75,000 gallons Maximum product surface area (PSA) is 846 ft2. |
| Waiting Time | Minimum of 4 hours, 48 minutes after delivery or transfer. |
| Test Period | Minimum of 6 hours. 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 0.874 inch. Minimum detectable change in water level is 0.011 inch. For tanks with a product surface area (PSA) of 564 ft2 and containing 0.874 inches of water, system takes more than 64 days 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 50,000 gallon tank with PSA of 564 ft2. |
- 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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