Issue Date: April 18, 1997
Revision Date: December 6, 2002
NON-VOLUMETRIC TANK TIGHTNESS
TEST METHOD (ULLAGE)
||Leak rate of 0.1
gph with PD = 95.24% and PFA = 0%.
||A tank system
should not be declared tight when the make-up gas flow rate into ullage
equals or exceeds 0.275 cubic feet/hour.
aviation fuel, fuel oil #4.
volume is 7,500 gallons.
||Minimum of 2
hours between delivery and testing.
||Minimum of 20
minutes, consisting of 2 consecutive 10-minute test periods.
Test data are acquired and recorded manually.
There must be no dispensing or delivery during test.
||Pressure must be
increased in ullage such that total pressure at bottom of tank does not
exceed 5.0 psi.
Pressure must be maintained for a minimum of 5 minutes per 1,000 gallons
At conclusion of this stabilization period, ullage pressure must be
reduced by 0.5 psi for remainder of test.
||Ullage must be
monitored for rate of temperature change, which must not exceed
manufacturer's tabulated values.
groundwater in tank excavation backfill must be determined.
If groundwater is above product level, net pressure must exceed 1 psi in
the ullage during test.
If this requires more than 5 psi total pressure at tank bottom, the ullage
test must not be used.
using manifolded tank systems.
Evaluated using diesel. Tests only ullage portion of tank.
Product-filled portion of tank must be tested using a volumetric underfill
Midwest Research Institute
Manufacturer’s Previously Listed Contact Information is No