Determining the location of a leak in an underground gas line has long posed difficult problems for gas line repair crews. Although the gas line itself is easily located, the soil is often saturated, which makes it difficult to pinpoint the actual location of the leak. As a result, it has not been uncommon for large stretches of a surface, including paved roadways, to be excavated in a somewhat random fashion. This, of course, is costly and time-consuming. In addition, the continuous leaking gas creates a greater hazard the longer the leak continues.
The conception of the Vapor Extraction Unit (V.E.U.) was developed by Atmos Energy. Their challenge was to remove residual gas quickly and safely, while monitoring the percent of gas in the moving air.
Solution and Success
An Integral LEL monitor alarms the operator when dangerous gas concentrations are approached. A bypass valve then allows the operator to configure the V.E.U. as necessary. The V.E.U. was so successful at removing residual gas that different applications were explored.
Current applications include the pinpointing of leaks on cast iron pipes and residual gas remediation. Some use the V.E.U. purely for pinpointing leaks. Accurate pinpointing has made "keyhole technology" viable, reduced "dry holes," and increased overall efficiency. Using the V.E.U. for gas remediation allows businesses that may have residual gas underneath or around the foundation to promptly reopen – avoiding expensive downtime.
How the V.E.U. Travels
Truck mounted units are used in the metroplex. Trailer mounted units are used in non-metro areas and are designed to be mobile from district to district.