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Issue Date: November 22, 1995
Revision Date: May 23, 2011
Hasstech
Leak Computer
Tank Test System
VOLUMETRIC TANK TIGHTNESS TEST
METHOD (UNDERFILL)
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.
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| 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. |
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Hasstech
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Evaluator:
Law Engineering Industrial Services
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out
of business
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Tel:
(800) 672-6601
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Date
of Evaluation: 04/17/91
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