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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 = 95.0% and PFA = 0.1%
for Quick Test.
Leak rate of 0.1 gph with PD = 95.2% and PFA = 2.5%
for 0.1 gph Test
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Leak
Threshold
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0.124 gph for leak rate
of 0.2 gph, Precision Test.
0.168 gph for leak rate of 0.2 gph, Quick Test.
0.067 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 test mode as
follows:
For Quick Test, the minimum product level is computed
as probe length multiplied by 0.12 plus 5 inches.
For Precision Test and 0.1 gph Test, the minimum product
level is 50% of tank capacity.
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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 resistance temperature
detectors (RTDs).
The bottom RTD 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 0.874
inch.
Minimum detectable water level change is 0.011 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
0.874 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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