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Issue Date: November 22, 1995
Revision Date: February 6, 2015
Purpora Engineering, Inc.
(originally listed by Alert Technologies, Inc.)
Alert Ullage System Model 1050
X
(Vacuum Test)
NON-VOLUMETRIC TANK TIGHTNESS
TEST METHOD (ULLAGE)
| Certification |
Leak rate of 0.1 gph with PD = 100% and PFA
= 0%. |
| Leak
Threshold |
A tank system should not be declared tight
if the ratio of the ultrasonic signal (when the tank is under vacuum) to
the background signal (prior to evacuation) equals or exceeds 1.5 for
either 12 kHz or 25 kHz frequency band. |
| Applicability |
Gasoline, diesel, aviation fuel, fuel oil
#4, waste oil. |
| Tank
Capacity |
Maximum ullage volume is 24,000 gallons. |
| Waiting
time |
None between delivery and testing if test
is conducted after an under filled tank tightness test. |
| Test
Period |
Minimum of 5 minutes.
Test data are acquired and recorded by system's computer.
There must be no dispensing or delivery during test. |
| Test
Pressure |
Vacuum of 1.5 psi must be maintained in
ullage.
Vacuum must be maintained in the tank with a loss of less than 0.4 psi.
Zero pressure (background) must produce a flat line response. |
| Temperature |
Ultrasonic and background signals are
independent of product temperature. |
| Groundwater |
Depth to groundwater in tank excavation
backfill must be determined.
If groundwater is present outside ullage, test must not be used. |
| Calibration |
System must be calibrated before each test. |
| Comments |
Manifolded tank systems must be isolated
prior to test. Evaluated using #4 fuel oil.
Tests only ullage portion of tank.
Product-filled portion of tank must be tested using an underfill test
method.
Vibration due to nearby equipment or dripping condensation may interfere
with test.
Microphone was located 25 feet away from leak source during
evaluation.
Vacuum test method 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 the tank excavation backfill may
help identify presence of this condition.
The manufacturer
does not support test results if the technician does not hold a current
Alert Technologies certification when the test is performed.
Recertification is required by the manufacturer every two years. |
Purpora Engineering Inc. |
Evaluator: Midwest Research Institute |
658 North Progress Drive |
Tel:
(816) 753-7600 |
Saukville, WI 53080 |
Date
of Evaluation: 03/11/91 |
Tel: (262) 536-4081 |
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E-mail: info@purporaengineering.com |
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URL: www.purporaengineering.com |
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