Issue Date: April 18, 1997
Revision Date: September 11, 1998

Tidel Engineering, Inc.

Tidel Environmental Monitoring System, 3500 Series
(Ultrasonic Probes #401-0009, #401-0010, #401-0023)

Automatic Tank Gauging Method

Certification Leak rate of 0.2 gph with PD = 95.3% and PFA = 4.7% for 2 hour test.
Leak rate of 0.2 gph with PD = 99.5% and PFA = 0.5% for 4 hour test.
Leak Threshold 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.
Other liquids may be tested after consultation with the manufacturer.
Tank Capacity Maximum of 15,000 gallons.
Tank must be between 50 and 95% full.
Waiting Time Minimum of 2 hours, 29 minutes between delivery and testing.
Minimum of 15 minutes after dispensing.
There must be no delivery during waiting time.
Test Period Minimum of 2 hours to achieve PD = 98.6% and PFA = 1.4%.
Minimum of 4 hours to achieve PD = 99.5% and PFA = 0.5%.
Test data are acquired and recorded by the microprocessor contained within the EMS console.
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 1.48 inches.
Minimum detectable water level change is 0.035 inch.
Calibration Temperature sensors and ultrasonic 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.The water sensor, temperature sensor, and product level monitor are contained in a single ultrasonic probe. Not evaluated using manifolded tank systems.
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.

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.
  • Tidel Engineering, Inc.
    2310 McDaniel Dr.
    Carrollton, TX 75006
    Tel: (800) 678-7577
  • Evaluator: Ken Wilcox Associates
    Tel: (816) 443-2494
    Date of Evaluation: 03/16/95

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