| Certification |
Leak rate of 0.1 gph with PD = 98.2% and
PFA = 1.8% for 2 hour test.
Leak rate of 0.1 gph with PD = 99.8% and PFA = 0.2% for 4 hour test. |
| 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, fuel oil
#4, waste oil.
Other liquids may be tested after consultation with the manufacturer. |
| Tank
Capacity |
Maximum of 30,000 gallons.
Tank must be between 20 and 95% full. |
| Waiting
time |
Minimum of 1 hour between delivery and
testing.
Minimum of 1 minute between dispensing and testing.
There must be no delivery during waiting time. |
| Test
Period |
Minimum of 2 hours to achieve PD = 98.2%
and PFA = 1.8%.
Minimum of 4 hours to achieve PD = 99.8% and PFA = 0.2%.
Test data are acquired and recorded by system's computer.
Leak rate is calculated from the data determined to be valid by
statistical analysis.
There must be no dispensing or delivery during test. |
| Temperature |
System measures product mass (which is not
affected by temperature) instead of product volume. |
| 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 2 psi at bottom of tank during
test. |
| Calibration |
Load cell must be calibrated before each
test. |
| 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. |
