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Xerxes Corporation-Tank Accessories http://www.xerxescorp.com/noframes/tacces.htm Remvdr LetiYa G#OOiati Rti ixvei Down Xerxes DWT-II double wall tanks with the TRU-CHEK®system option are factory-filled with a brine solution in the interstice between the two tank walls.The brine also partially fills a reservoir affixed to the top of the tank.This creates a hydrostatic pressure that enables owners/users to monitor both the primary and secondary tank walls.The TRU-CHEO system provides a simple and precise method to perform a tank-tightness test.It was developed in conjunction with Dr.Robert Plunkett,Sc.D.,consulting engineer(professor emeritus),University of Minnesota. HOW CONTINOUS MONITORING WORKS: If both the inner and outer walls are tight,the reservoir level will be stable.If there is a fracture in the inner wall (Diagram A),the brine level in the reservoir will go down. The brine level in the reservoir will also go down if there is a leak in the outer wall(Diagram B). With a high water table and"wet hole"conditions(Diagram C),a 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. AlmmT+nk _tem up - Fractwe Quuv WaRM,� The TRU-CHEO test offers significant benefits to the owner or operator: 1. A wide range of tank sizes,including Xerxes DWT-11 tanks up to 20,000 gallons. 2. Product can be dispensed during the 95°/u/5%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 Degrees F.from the existing product temperature. The 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 part of the tank that routinely contains product.The test has a 95%probability of detection(PD)and a 5%probability of a false alarm(PFA).In other words,the test detects leaks 95%of the time. The test must also account for the effects of thermal expansion or contraction of the product,vapor pockets,tank deformation,evaporation,condensation and the location of the water table. TRU-CHEO is capable of detecting a loss rate as small at the NFPA 329 criteria of 0,05 gallons per hour.In addition,on extended tests,TRU-CHEKO testing offers 99%PD and 1%PFA. XERXESO CORPORATION 7901 Xerxes Ave.So.,Minneapolis,MN 55431-1882 Phone:(612)887-1890 Fax:(612)887-1882 E-mail:info@xerxescor 7 of 7 05/19/2000 3:01 PM