Issue Date: November 22, 1995
Revision Date: April 27, 2005

Purpora Engineering, Inc.

(Originally listed as Heath Consultants, Inc.)

Petro Comp

Volumetric Tank Tightness Test Method (Overfill)

Certification Leak rate of 0.1 gph with PD = 99% and PFA = 0.98%.
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.
Other liquids with known coefficients of expansion and density may be tested after consultation with the manufacturer.
Tank Capacity Maximum of 15,000 gallons.
Tank must be minimum 100% full.
An automatic product leveler must be used to maintain a constant product level during test.
Waiting Time None between delivery and testing.
There must be no dispensing or delivery during waiting time.
Test Period Minimum of 2 hours after the completion of the high level circulation.
Test data are acquired and recorded by system's computer after the completion of the high level circulation.
Leak rate is calculated based on cumulative volume change during low level test (generally based on 1 hour average volume change).
Product must be mixed continuously throughout test period. There must be no dispensing or delivery during test.
Temperature Average for product is determined by a single temperature sensor.
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 4 psi at bottom of tank during test.
Calibration Temperature sensor is self calibrating.
Level sensor must be checked annually and, if necessary, calibrated in accordance with manufacturer's instructions.
Comments Not evaluated using manifolded tank systems.

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