Issue Date: November 22, 1995
Revision Date: December 6, 2002
Tanknology - NDE
UTS-4T Ullage Test (Pressure Test)
Non-Volumetric Tank Tightness Test Method (Ullage)
| Certification | Leak rate of 0.1 gph with PD = 95.24% and PFA = 0%. |
|---|---|
| Leak Threshold | A tank system should not be declared tight when the make-up gas flow rate into ullage equals or exceeds 0.275 cubic feet/hour. |
| Applicability | Gasoline, diesel, aviation fuel, fuel oil #4. Other liquids may be tested after consultation with the manufacturer. |
| Tank Capacity | Maximum ullage volume is 7,500 gallons. |
| Waiting Time | Minimum of 2 hours between delivery and testing. |
| Test Period | Minimum of 20 minutes, consisting of 2 consecutive 10-minute test periods. Test data are acquired and recorded manually. There must be no dispensing or delivery during test. |
| Test Pressure | Pressure must be increased in ullage such that total pressure at bottom of tank does not exceed 5.0 psi. Pressure must be maintained for a minimum of 5 minutes per 1,000 gallons of ullage. At conclusion of this stabilization period, ullage pressure must be reduced by 0.5 psi for remainder of test. |
| Temperature | Ullage must be monitored for rate of temperature change, which must not exceed manufacturer's tabulated values. |
| Groundwater | Depth to groundwater in tank excavation backfill must be determined. If groundwater is above product level, net pressure must exceed 1 psi in the ullage during test. If this requires more than 5 psi total pressure at tank bottom, the ullage test must not be used. |
| Comments | Not evaluated using manifolded tank systems. Evaluated using diesel. Tests only ullage portion of tank. Product-filled portion of tank must be tested using a volumetric underfill test method. |
- Tanknology - NDE
8900 Shoal Creek Blvd., Building 200
Austin, TX 78757
Tel: (800) 800-4633 - Evaluator: Midwest Research Institute
Tel: (816) 753-7600
Date of Evaluation: 12/04/92
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