Issue
Date: November 22, 1995
Revision Date: March 20, 2003
Sound
Products Manufacturing, Inc.
(originally listed as
USTest, Inc.)
UST
2000/LL
VOLUMETRIC
TANK TIGHTNESS TEST METHOD (UNDERFILL)
USTest, Inc.,
no longer supports the use of this method *
|
Certification
|
Leak
rate of 0.1 gph with PD = 98.12% and PFA = 1.88%.
|
|
Leak
Threshold
|
0.05
gph.
A tank system should not be declared tight if the test
result indicates a loss or gain that equals or exceeds
this threshold.
|
|
Applicability
|
Gasoline,
diesel, aviation fuel, water, kerosene.
Other liquids may be tested after consultation with the
manufacturer.
|
|
Tank
Capacity
|
Maximum
of 15,000 gallons.
Tank must be between 65% and 95% full. |
|
Waiting
Time
|
Ranges
from 3 to 12 hours between delivery and testing.
Testing may begin when the rate of product temperature
change does not exceed 0.1 degree F per hour.
There must be no dispensing or delivery during waiting
time.
|
|
Test
Period
|
Minimum
of 2 hours.
Test data are acquired and recorded by system's computer,
which does a regression analysis to determine the leak
rate.
An ultrasonic device is used to measure changes in product
level.
There must be no dispensing or delivery during test.
|
|
Temperature
|
Average
for product is determined from the measurement of the
change in the speed of sound.
|
|
Groundwater
|
Depth
to groundwater in tank excavation backfill must be determined.
If groundwater is above bottom of tank, product level
must be adjusted to provide a minimum net pressure of
1 psi at bottom of tank during test. (There must be a
difference of at least 37 inches between groundwater level
and product level to provide a net pressure of 1 psi at
bottom of tank during test.)
|
|
Calibration
|
Temperature
sensors and probes must be checked annually and, if necessary,
calibrated in accordance with manufacturer's instructions.
|
|
Comments
|
Not
evaluated using manifolded tank systems.
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.
* USTest Inc. has requested
removal of the 2000/LL equipment from the NWGLDE List
and discourages the use of this method due to software
security and data integrity problems.
|
