INSTALL_2006 - Laserfiche WebLink

Home Browse Search

7AD Daunt Xerxes DWT -11 double-wall tanks with the TRUCHEK® 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 hydrosta- tic pressure that enables owners/users to monitor both the primary -tank and the secondary -tank walls. The TRUCHEK® system provides a simple and precise method to perform a tank -tightness test. It was developed in conjunc- tion with Robert Plunkett, Sc.D., consulting engineer (profes- sor emeritus), University of Minnesota. TRUCHEK° has received third -parry verification from Underwriters Laboratories. TRUCHECK® testing meets the EPA criteria for tank -tightness testing, which states that a test must be able to detect a leak rate of 0. i 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 water table. TRUCHECKO is capable of detecting a loss rate as small as the NFPA 329 criteria of 0.05 gallons per hour. In addition, on extended tests, TRUCHEK® testing offers 99% PD and i % PFA. The TRUCHE® Tssl bars Significant Bien, slits tD 1ha D1mnarjD. pa tDr,: 1. A wide range of tank sizes can be tested, including Xerxes DWT -11 tanks up to 20,000 gallons. 2. Product can be dispensed during the 95%-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°F from the existing product temperature. How Continuous Monitoring Works If both the inner and outer walls are tight, the reservoir level will be stable. (fl If there is a fracture in the inner wall (Diagram A), the brine level in the reservoir will go down. The brine level 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. See Xerxes TRUCHEK" brochure for more details. 16 Diagram A Reservoir Level Down Diagram B Reservoir Level Down s Diagram C �1 �1 M- -Reservoir 1 Level Up 1 Water Level Above Tank Fracture �f U� r� �r �r w Outer Wall 2