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Issue Date: April 28, 2005
MassTech
International, Ltd.
MassTech 002
Ullage Test System
(Pressure or Vacuum Test)
NON-VOLUMETRIC TANK TIGHTNESS
TEST METHOD (ULLAGE)
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Certification |
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 a predetermined
threshold is exceeded.
This threshold may be modified by the results of the static test.
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Applicability |
Gasoline, diesel, aviation fuel, fuel oil #4, waste oil.
Empty tanks may also be tested.
Tests only ullage portion of the tank.
Product-filled portion of the tank must be tested using an underfill test
method. |
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Tank Capacity |
Maximum ullage volume is 30,000 gallons. |
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Waiting Time |
2.38 hours with tank filled to 5%
1.5 hours with tank filled to 50%
0.27 hours with tank filled to 95%
The wait time
may be shortened by the technician when steady state conditions are reached
earlier. |
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Test Period |
Total collection time is 2.63 hours with tank filled to 5%
Total collection time is 1.75 hours with tank filled to 50%
Total collection time is 0.52 hours with tank filled to 95%
The 25-minute static test in which the tank is sealed but not pressurized
may be shortened by the technician when steady state conditions are reached
earlier.
Test data is
acquired by computer and forwarded electronically to an analysis center
where proprietary software is used to assist in the determination of the
tank condition. |
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Test Pressure |
A nominal pressure or vacuum of 1.5 psig must be maintained
in the ullage. |
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Temperature |
Method is sensitive to temperature, atmospheric pressure and
other environmental fluctuations.
These are empirically modeled during the static test. |
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Groundwater |
Depth to groundwater in tank excavation backfill must be
determined.
If
groundwater is above tank bottom, a water sensor must be located at the
bottom of the tank or the test must be conducted in conjunction with the
standard MassTech wet test. |
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Comments |
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. |
Evaluator: Ken Wilcox
Associates, Inc. |
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102 Basile Road |
Tel: (816) 443-2494 |
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Scott, LA 70583 |
Date of Evaluation:
02/21/05 |
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Tel: (337) 896-8230 |
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E-mail: masstech1@compuserve.com |
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URL:
http://masstechinternational.com |
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