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Ameron International Fiberglass-Composite Pipe Division <br /> Dualoy® 3000/LCX <br /> Brine Filled Interstitial Space <br /> Assembly, Charging and Activation Procedure <br /> I. Introduction <br /> Brine filling of the interstitial space between the inner and outer walls of <br /> Underground Storage Tanks (UST's) has been used for many years to signal <br /> possible leaks (hydrostatic monitoring). The same monitoring and sensing <br /> equipment used for UST's can also be used with piping. Configuring piping to <br /> accommodate this feature is a significant step forward in leak prevention and <br /> environmental protection. <br /> The small volume of the interstitial space between the primary and secondary <br /> fiberglass pipe walls of the Dualoy 3000/LCX system allows the practical use of <br /> brine to provide continuous leak monitoring. This same concept and equipment <br /> can be used to monitor the containment of a pipe-in-a-pipe (3-over 2, for <br /> example), but the coaxial construction of the "LCX" system has particular <br /> advantages. <br /> Two features of the "LCX" product make its use with the monitoring system very <br /> beneficial. First, the interstitial volume is low, requiring a small quantity of brine <br /> to fill the system. Second, the strength and stiffness of both the primary and <br /> secondary fiberglass pipe walls of LCX keep it from significantly changing <br /> interstitial volume under the normal range of temperature and pressure <br /> conditions during operation. <br /> If the primary wall of the LCX expands slightly under pressure, the containment <br /> wall will also expand since the gap between them is filled with particulate. With <br /> the walls responding this way, the change in volume between them is very small. <br /> If a 2-inch primary pipe expands within a 3-inch containment pipe, there is no <br /> "resistance" by the containment pipe. The expanding primary and the stagnant <br /> containment results in a greater change in the interstitial volume. <br /> This allows the brine reservoir, the piece of the system where the volume change <br /> will be measured, to be relatively smaller for the LCX system. <br /> When the nozzle shuts off at the dispenser, a pressure wave travels down the <br /> pipe to halt the flow of fuel. The stiffness of fiberglass pipe causes the pressure <br /> "pulse" to have little effect on the interstice. The pulse will cause more flexible <br /> materials to expand momentarily and result in a "spurt" of fluid into (and possibly <br /> out of) the reservoir from the interstice. <br />