Issue Date: November 22, 1995
Revision Date: May 23, 2007
EZY CHEK Systems
(originally listed as Horner EZY CHEK)
NON-VOLUMETRIC TANK TIGHTNESS
TEST METHOD (VACUUM)
||Leak rate of 0.1
gph with PD = 100% and PFA = 0%.
||A tank system
should not be declared tight when the vacuum decay is more than 1 inch
water column pressure for non-volatile products and 10% of the lower
determined vapor pressure for volatile products, or when water ingress is
detected by the water sensor.
aviation fuel, fuel oil #4, waste oil.
||Maximum of 12,000
gallons if groundwater is not present.
Maximum of 50,000 gallons if groundwater is present and a vacuum of 1.0 to
1.7 psi can be maintained.
For gasoline, ullage volume must be between 800 and 2,500 gallons.
For diesel, ullage volume must be between 500 and 1,500 gallons.
delivery and testing.
||Minimum of 2
hours, 30 minutes for gasoline (1 hour, 30 minutes vapor equilibrium
recirculation time* plus 1 hour test period) when groundwater is below
bottom of tank.
Minimum of 1 hour, 30 minutes for diesel and less volatile products (30
minutes vapor equilibrium recirculation time* plus 1 hour test period)
when groundwater is below bottom of tank.
Minimum of 1 hour when groundwater is above bottom of tank.
Test period based on water ingress depends on tank size and must be
calculated in accordance with manufacturer's instructions.
Test data are acquired and recorded manually.
There must be no dispensing or delivery during test.
*The vapor equilibrium recirculation time is the time required to apply a
vacuum and to saturate ullage with vapors.
||Vacuum must be
maintained between 1.0 to 1.7 psi at bottom of tank.
Vacuum must not be greater than 4.0 psi in ullage.
||Vacuum decay is
independent of product temperature.
water sensor must be used to detect water ingress and must be calibrated
for every test.
Minimum detectable water level is 0.014 inch. Minimum detectable change in
water level is 0.0095 inch.
Minimum water level in tank must be adjusted to 0.014 inch before
calibrating the sensor.
groundwater in tank excavation backfill must be determined.
If groundwater is above bottom of tank, water sensor must be used and test
time extended to ensure water ingress detection during test.
using manifolded tank systems.
Evaluated using gasoline and diesel.
Test may not be effective in some tank excavation backfill (such as clay)
because it may plug holes in tank.
If soil is saturated with product, air or water ingress may not be
detected by vacuum test.
A well point in tank excavation backfill may help identify presence of
EZY CHEK Systems
Ken Wilcox Associates