Issue Date: April 18, 1997
Revision Date: May 23, 2007

Caldwell Systems Corp.

Tank Manager (Ultrasonic Probe)

Automatic Tank Gauging Method

Certification Leak rate of 0.2 gph with PD = 99.9% and PFA = 0.1%. Leak rate of 0.1 gph with PD = 96.7% and PFA = 3.3%.
Leak Threshold 0.1 gph for leak rate of 0.2 gph. 0.05 gph for leak rate of 0.1 gph. A tank system should not be declared tight if the test result indicates a loss or gain that equals or exceeds this threshold.
Applicability Gasoline, diesel, aviation fuel, fuel oil #4, waste oil. Other liquids may be tested after consultation with the manufacturer.
Tank Capacity Maximum of 20,000 gallons.
Minimum product level required to conduct a test is 18 inches.
Waiting Time Minimum of 12 hours, 25 minutes between delivery and testing. Minimum of 15 minutes between dispensing and testing. There must be no delivery during waiting time.
Test Period Minimum of 3 hours, 15 minutes. Test data are acquired and recorded by system's computer. Leak rate is calculated from data determined to be valid by statistical analysis. There must be no dispensing or delivery during test.
Temperature Average for product is determined from the measurement of the change in the speed of sound.
Water Sensor Must be used to detect water ingress. Minimum detectable water level in the tank is 0.921 inch. Minimum detectable change in water level is 0.0315 inch.
Calibration Probe must be checked and, if necessary, calibrated in accordance with manufacturer's instructions.
Comments

Not evaluated using manifolded tank systems. Therefore, this certification is only applicable when there is a probe used in each tank and the siphon is broken during testing.
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. EPA leak detection regulations require testing of the portion of the tank system which routinely contains product. Water sensor, temperature sensor and product level monitor are contained in a single ultrasonic probe.

California regulations require at least one test per month after routine product delivery or when the tank is filled to within 10% of the highest operating level of previous month. If the 0.1 gph test is used as a tank tightness test there must be no water present in the backfill (groundwater must be below the bottom of the tank), the tank must be equipped with an overfill protection device, and the product level in the tank must be at the overfill protection device set point. Local agency pre-approval is required. To use the 0.1 gph test as a monthly option see title 23 CCR Section 2643 (b)(2).
  • Caldwell Systems Corp.
    600 South Sunset Street, Unit D
    Longmont, CO 80501
    Tel: (303) 684-8436
  • Evaluator: Ken Wilcox Associates
    Tel: (816) 443-2494
    Date of Evaluation: 04/22/96, 4/05/99

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