Overview
The LT-100 is independently certified and is listed by the NWGLDE
as complying with all EPA protocols.
When the volume of fuel is less than 3400 gallons—roughly 1300 feet of 8- inch-diameter pipe—the LT-100 can reliably detect leaks as small as 0.1 gallon per hour. When the volume is greater than 3400 gallons it can detect a leak equivalent in size to 0.0021% of the total volume per hour. Most importantly, through its algorithm for temperature compensation, the LT-100 overcomes some of the major deficiencies of conventional pressure tests.
The LT-100 is a computer- controlled, fully automatic system. All data are acquired and processed electronically. As shown in the schematic diagram at right, the LT-100 sensor unit consists of (1) a measurement cylinder (Tank 1); (2) a storage cylinder (Tank 2); (3) a differential pressure sensor to measure level changes in the measurement cylinder electronically; (4) a pump for transferring fuel from the measurement cylinder or storage cylinder to the line in order to increase line pressure to a specified level; and (5) two pressure relief valves and a bypass valve for removing fuel from the line and adding it to the measurement cylinder or storage cylinder in order to decrease the pressure in the line to a specified level. When combined, the pump and the pressure relief valves can be used to maintain a constant pressure in the line at a specified level. The size of the cylinders is determined by the capacity of the largest pipeline segment that will be tested at a given site.
The storage cylinder is normally used to set or change the overall pressure in the line. (Pressure can also be set or changed with the pressure management system used to operate the line or by adding or removing fuel from a nearby tank, tanker truck, or pipeline.) The measurement cylinder is normally used to maintain constant pressure during a test and to make the volume measurements required during the test. A test can be conducted with the measurement cylinder alone if there is no need for the extra storage capacity that Tank 2 provides. The pump and pressure-relief-valve system are used to adjust and maintain a constant pressure in the line. As shown by the valves on the "ladder," the system can be operated at three pressures: a high pressure, a low pressure, and atmospheric pressure (by means of the bypass valve). The high- and low-pressure relief valves can be set to operate at any desired pressure. Finally, a pressure relief valve and an overfill alarm in each cylinder ensure safe operation of the system.
Benefits
Several attributes set the LT-100 apart from other leak detection systems in its class.
Short Tests
The LT-100 conducts a pipeline test in 2 hours. Because it compensates for thermal expansion and contraction of the liquid in the line during a test, it eliminates the need for the long pre-test waiting periods that are typically used to assure thermal stabilization (as recommended by API standard RP 1110 on hydrostatic pressure tests).
Fully Automated
The LT-100 is a fully automated system that is easily installed and operated. Once a test is initiated, a programmable logic controller governs the system operations.
On-the-Spot Results
Easy-to- interpret results are available immediately after the completion of the test. The LT-100 provides a direct measure of the leak rate in gallons per hour at the test pressure (that is, the normal operating pressure of the pipeline).
Accurate and Reliable
Each test includes a self-check on the "goodness" of the test result—a built-in safeguard that establishes the credibility of the result and minimizes the chance of a false alarm or missed detection. This safeguard takes the form of a calculation called the "test error," which is a direct estimate of the accuracy of the temperature compensation achieved during the test. The LT-100 calculates a test error and uses it to determine the validity of the result of every test.
Owner/Operator Control
The LT- 100 test can be run, and its results easily interpreted, by the owner of the pipeline. Tests can be conducted with any desired frequency.
Certified Performance
The LT-100 has been certified by an independent third party (Ken Wilcox Associates, Inc.); this evaluation is listed by the National Work Group on Leak Detection Evaluations as complying with all established EPA protocols.
Installation
The LT-100 sensor unit is attached to the line at a single location, by means of a valve. Any convenient location along the line will do. The fuel remains in the line during a test, but all transfer operations must be suspended. The line must be completely isolated, by means of valves, from any storage tanks connected to it and from other sections of line not being tested. If the valves used to isolate the line do not seal properly, either a double block and bleed valve or valve blinds must be installed.
Mobile LT-100
Vista offers its LT-100 either as a permanent installation or as a mobile system. The mobile LT-100, typically installed in a truck, can be transported to different sites whenever periodic testing of a pipeline is needed.
