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)


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.

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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