||Leak rate of 0.1
gph with PD = 99.9% and PFA = 0.1%.
A tank system should not be declared tight if the test result indicates a
loss or gain that equals or exceeds this threshold.
aviation fuel, fuel oil #4.
||Maximum of 18,000
Minimum product level required is 24 inches.
||Must be long
enough between delivery and testing to ensure a temperature change of less
than 0.09 degrees F per hour, typically a minimum of 2 hours.
There must be no delivery during waiting time.
||Minimum of 2
Test data are acquired and recorded by system's computer.
Leak rate is calculated from average over data window.
There must be no dispensing or delivery during test.
product is typically determined by 5 thermistors.
A minimum of 1 thermistor is required.
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.
be checked annually and, if necessary, calibrated in accordance with
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
EPA leak detection regulations require testing of the portion of the tank
system which routinely contains product.