Issue
Date: November 22, 1995
Revision Date: April 14, 2015
AMETEK Automation & Process Technologies
(originally listed as
MagneTek, then Patriot
Sensors and Controls Corp.)
7021
Digital Tank Gauge
(7030 Series Magnetostrictive Probe)
AUTOMATIC
TANK GAUGING METHOD
As of 2005, the 7021 product line became obsolete.
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Certification
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Leak
rate of 0.2 gph with PD = 99.96% and PFA = 0.044%.
Leak rate of 0.1 gph with PD = 95.34% and PFA = 4.66%.
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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, fuel oil #4.
Other liquids with known coefficients of expansion and
density and where specific gravity is > 0.6 and viscosity
is < 1500 cp may be tested after consultation with
manufacturer.
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Tank
Capacity
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Maximum
of 15,000 gallons.
Tank must be between 50 and 95% full for leak rate of
0.2 gph.
Tank must have minimum product height of 18 inches, or
be 14% full, whichever is higher, for leak rate of 0.1
gph.
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Waiting
Time
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Minimum
of 2 hours between delivery and testing for leak rate
of 0.2 gph.
Minimum of 8 hours between delivery and testing for leak
rate of 0.1 gph.
There must be no dispensing or delivery during waiting
time.
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Test
Period
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Minimum
of 4 hours.
Test data are acquired and recorded by a 7021 controller
(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 minimum of 1 resistance
temperature detector (RTD).
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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 0.947 inch.
Minimum detectable water level change is 0.0254 inch.
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Calibration
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RTD
and probe 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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