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Issue Date: November 22, 1995
Revision Date: September 22, 2009
Tanknology
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. |
| 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. |
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Tanknology
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Evaluator:
Midwest Research Institute
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11000 North MoPac Expressway, Suite 500
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Tel:
(816) 753-7600
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Austin, TX 78759
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Date of
Evaluation: 12/04/92
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Tel: (800) 800-4633
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