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Certification
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Leak
rate of 0.2 gph with PD = 99.9% and PFA = 0.1% for Precision
Test.
Leak rate of 0.2 gph with PD = 97.0% and PFA = 0.1% for
Quick Test.
Leak rate of 0.1 gph with PD = 95.2% and PFA = 0.8% for
0.1 gph Test
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Leak
Threshold
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0.1
gph for leak rate of 0.2 gph, Precision Test.
0.128 gph for leak rate of 0.2 gph, Quick Test.
0.06 gph for leak rate of 0.1 gph, 0.1 gph Test.
A tank system should not be declared tight if the test
result indicates a loss that equals or exceeds this threshold.
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Applicability
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Gasoline,
diesel, aviation fuel, fuel oil #4.
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 20,000 gallons.
Tanks less than 95% full may be tested.
Minimum product level required based on tank diameter
is as follows:
48" dia/ min 18";
64" dia/ min 21";
72" dia/ min 24";
96" dia/ min 30";
126" dia/ min 39".
Minimum product level required for other tank diameters;
multiply probe length by 0.08 and add 5 inches.
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Waiting
Time
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Minimum
of 1 hour between delivery and testing for Quick Test.
Minimum of 6 hours between delivery and testing for Precision
Test and 0.1 gph Test.
There must be no delivery during waiting time.
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Test
Period
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Minimum
of 2 hours for all tests.
Test data are acquired and recorded by system's computer.
Leak rate is calculated from data determined to be statistically
valid.
There must be no dispensing or delivery during test.
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Temperature
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Average
for product is determined by a probe with 5 thermistors.
The bottom thermistor must be submerged in at least 5
inches of product during test.
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Water
Sensor
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Must
be used to detect water ingress.
Minimum detectable water level in the tank is 0.878 inch.
Minimum detectable water level change is 0.013 inch.
System is default programmed to report a water depth only
when it exceeds 3.5 inches.
System can be programmed to report a water depth of 0.878
inch and above.
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Calibration
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System
must be checked 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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