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t - TRUI -- doub -Aew ' 4al NseSs . - - Xerxes D\VT4I double wall tanks with the TRU-CHEK®system Diagram A option are factory-filled with a brine solution in the interstice between the two tank walls.The brine also partially fills a Reservoir reservoir affixed to the top of the tank.This creates a hydrosta• Level Down tic pressure that enables owners/users to monitor both the primary tank and the secondary tank walls. The TRU-CHEK®system provides a simple and precise method to perform a tank-tightness test. It was developed in�onjunc tion with Dr. Robert Plunkett, Sc.D.,consulting engineer(pro- fessor emeritus), University of Minnesota.TRU-CHEK®has . received third-party verification from Underwriters Laboratories. TRU-CHEK®testing meets the EPA criteria for tank-tightness testing,which states that a test must be able to detect a leak rate of 0.1 gallon per hour from any portion of the tank that routinely contains product:The test has a 95%probability of detection(PD)and a 5%probability of false alarm(PFA). In other words,_ out of 100 chances, the test detects leaks 95% of the time. The test must also account for the effects of thermal expan- sion or contraction of the product, vapor pockets, tank defor- mation, evaporation, condensation and the location of the Diagram B water table. TRU-CHEK®is capable of detecting a loss rate as small as the LevelD"wn NFPA 329 criteria of 0.05 gallons per hour. In addition, on extended tests,TRU-CHEK®testing offers 99% PD and I%PFA. The TRU-CHEKO test offers significant benefits to the owner/operator: LA wide range of tank sizes can be tested, including Xerxes D%T4I tanks up to 20,000 gallon. 2.Product can be dispensed during the 9546/546 test. 3.No waiting time is required to start the test as long as a fill of new product does not vary more than 20°F from the existing product temperature. How continuous monitoring works If both the inner and outer walls are Diagram C tight, the reservoir level will be stable. If there is a fracture in the inner wall ------ Reservoir (Diagram A), the brine level in the Level Up - reservoir will go down.The brine level -�Water level will also go down if there is a leak in Above Tank the outer wall(Diagram B). With a high-water table and"wet- i�Fracture hole"conditions(Diagram C), a Outer Wall leak in the outer wall will cause the brine level to go up if the height of the water table above the leak is 30% greater than the brine level above the leak. See Xerxes TRU-CHEK® brochure for more details. 16