Issue Date: June 4, 2003
Revision Date: April 28, 2005
MassTech
International, Ltd.
MassTech Remote
Spectral Analysis Method
(Vacuum Test)
NON-VOLUMETRIC
TANK TIGHTNESS TEST METHOD (ULLAGE)
Certification
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Leak rate of 0.1 gph with
PD = 100% and PFA = 0%.
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Leak
Threshold
|
Tank ullage should not be declared
tight when the digital recording of the noise spectrum
of tank under vacuum has a detectable difference from
the digital recording of the noise spectrum of tank at
zero pressure.
|
Applicability
|
Gasoline,
diesel, aviation fuel, fuel oil #4, waste oil. Empty tanks
may also be tested. Tanks containing other liquids may
be tested after consultation with the manufacturer.
Tests only ullage portion of the tank.Product-filled portion
of the tank must be tested using an underfill test method.
|
Tank
Capacity
|
Maximum ullage volume is
20,000 gallons.
|
Waiting
Time
|
None between delivery and
testing.
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Test
Period
|
A
nominal vacuum of 1.5 psig must be maintained in the ullage.
|
Test
Pressure
|
A
nominal vacuum of 1.5 psig must be maintained in the ullage.
|
Temperature
|
Acoustic signal is independent
of product temperature.
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Groundwater
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Depth
to groundwater in tank excavation backfill must be determined.
If groundwater or other liquid is present outside tank
ullage, test must not be used.
|
Comments
|
Microphone
(hydrophone) should be located within 25 feet of any possible
leak source.
Data are digitally recorded so that it can be reviewed
by the test operator or other qualified individuals.
Since the method depends on an audible interpretation
of the signal, the test must be conducted under reasonably
quiet conditions.Vibrations due to heavy traffic, nearby
trains, or construction activities could produce sound
levels that could compromise the test.
Vacuum test method may not be effective in some tank excavation
backfill (such as clay) because it may plug holes in tank.
If free product is present in tank excavation backfill,
a leak in the free product zone may not be detected by
a vacuum test method.
A well point or observation well in the tank excavation
backfill may help determine backfill material, water level
in tank excavation backfill, and free product.
Operators must be trained and certified by the manufacturer.
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MassTech International, Ltd.
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Evaluator:
Ken Wilcox Associates, Inc.
|
102
Basile Road
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Tel:
(816) 443-2494
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Scott,
LA 70583
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Date
of Evaluation: 01/02/01
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Tel:
(337) 896-8230
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