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UST Program - LG 113

UST Program - LG 113

Issue Date: December 5, 2002

Engineering Design Group

Ronan X-76 CTM Automatic Tank Gauging System
(MTS Level Plus UST Probe)


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.

Evaluator:  Ken Wilcox Associates

800 Meridian Tower

Tel:  (816) 443-2494

5100 E. Skelly Drive

Date of Evaluation:  11/16/01

Tulsa, OK 74135


Tel: (918) 628- 7100


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