Issue
Date: Jully 19, 1996
Revision Date: April 4, 2007
USTest,
Inc.
(previously listed as
Sound Products Manufacturing, Inc.)
UST
2001 and UST 2001 Quick Test
(Ultrasonic Probe)
AUTOMATIC
TANK GAUGING METHOD
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Certification
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Leak
rate of 0.2 gph with PD = 97.5% and PFA = 2.5% for Quick
Test.
Leak rate of 0.1 gph with PD = 95.2% and PFA = 4.8%.
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Leak
Threshold
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0.1
gph for leak rate of 0.2 gph.
0.05 gph for leak rate of 0.1 gph.
A tank system should not be declared tight if the test
result indicates a loss or gain that equals or exceeds
this threshold.
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Applicability
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Gasoline,
diesel, aviation fuel. Other liquids with known coefficients
of expansion and density may be tested after consultation
with the manufacturer.
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Tank
Capacity
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Maximum
of 15,000 gallons. Tank must be between 50 and 95% full.
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Waiting
Time
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Minimum
of 4 hours between delivery and testing. Minimum of 15
minutes between dispensing and testing. There must be
no delivery during waiting time.
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Test
Period
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Minimum
of 30 minutes for leak rate of 0.2 gph (Quick Test).
With a test period of 1 hour, system has PD = 99.9% and
PFA = 0.1%.
Minimum of 1 hour for leak rate of 0.1 gph.
With a test period of 2 hours, system has PD = 98.6% and
PFA = 1.4%.
Test data are acquired and recorded by system's computer.
Leak rate is calculated from data determined to be valid
by statistical analysis. There must be no dispensing or
delivery during test.
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Temperature
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Average
for product is determined from the measurement of the
change in the speed of sound.
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Water
Sensor
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Must
be used to detect water ingress. water is declared via
an ultrasonic signal ranging to the water interface. Minimum
detectable water level in the tank is less than 0.1 inch.
Minimum detectable change in water level is 0.046 inch.
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Calibration
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Probe
must be checked regularly and, if necessary, calibrated
in accordance with manufacturer's instructions.
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Comments
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Not
evaluated using manifolded tank systems. Therefore,
this certification is only applicable when there is
a probe used in each tank and the siphon is broken during
testing.
Tests only portion of tank containing product. As product
level is lowered, leak rate in a leaking tank decreases
(due to lower head pressure).
Consistent testing at low levels could allow a leak
to remain undetected.
EPA leak detection regulations require testing of the
portion of the tank system which routinely contains
product.
California regulations
require at least one test per month after routine product
delivery or when the tank is filled to within 10% of
the highest operating level of previous month. If the
0.1 gph test is used as a tank tightness test there
must be no water present in the backfill (groundwater
must be below the bottom of the tank), the tank must
be equipped with an overfill protection device, and
the product level in the tank must be at the overfill
protection device set point. Local agency pre-approval
is required. To use the 0.1 gph test as a monthly option
see title 23 CCR Section 2643 (b)(2).
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