Issue Date: November 22, 1995
Revision Date: September 22, 2009

Tanknology

UST Ullage Test, Version U2 (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 pressure decay trend equals or exceeds 0.016 psi/hr.
Applicability Gasoline, diesel, aviation fuel, fuel oil #4.
Tank Capacity Maximum ullage volume is 10,260 gallons.
Waiting time Minimum of 2 hours between delivery and testing.
Test Period Minimum of 30 minutes (after data trend has been established).
There must be no dispensing or delivery during test.
Test Pressure Total pressure of 4.0 psi must be applied at bottom of tank.
Temperature Ullage must be monitored during test, and a correction factor is applied to account for temperature changes. 
If ullage temperature changes exceed 5 degrees F, test must not be conducted.
Groundwater Depth to groundwater in tank excavation backfill must be determined. 
If groundwater is above product level, net pressure must be maintained at a minimum of 1 psi in the ullage during test.
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

Evaluator:  ADA Technologies, Inc.

11000 North MoPac Expressway, Suite 500

Tel:  (303) 792-5615

Austin, TX 78759

Date of Evaluation:  04/10/92

Tel: (800) 800-4633

 

 

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