Issue Date: November 22, 1995
Revision Date: May 23, 2011


Leak Computer Tank Test System


Hasstech is no longer in business.

Certification Leak rate of 0.1 gph with PD > 99% and PFA < 1.0%.
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. 
Tank Capacity Maximum of 15,000 gallons. 
Tank must be minimum 90% full.
Waiting Time Test data are acquired and recorded by system's computer that calculates a leak rate every minute, and determines waiting time for satisfactory data (test is finished when the standard deviation of 30 sequential leak rates is less than half of the last leak rate determined). 
There must be no dispensing or delivery during waiting time.
Test Period Minimum of 1 hour, 10 minutes. 
Test data are acquired and recorded by system's computer. 
Leak rate is calculated from data determined to be valid by statistical analysis. 
There must be no dispensing or delivery during test.
Temperature Average for product is determined by a minimum of 7 thermistors.
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 1 psi at bottom of tank during test.
Calibration Level sensor must be calibrated before each test. 
Thermistors must be checked annually and, if necessary, calibrated in accordance with manufacturer's instructions.
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. 
System no longer being manufactured and no support is available.



Evaluator:  Law Engineering Industrial Services

out of business

Tel:  (800) 672-6601


Date of Evaluation:  04/17/91


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