Evolution of a totally fiber optic fluid detection system

As environmental and safety requirements for Aboveground Storage Tank (AST) operators increase, the demand for suitable leak detection equipment and methodology has brought about innovative sensor technology. Increasing opportunities to apply this new technology have arisen as state and local ordinances begin to mandate secondary containment and continuous leak detection. Similar federal requirements appear to be on the horizon. Due to the fact that most available leak detection systems have been devised for use in underground storage tank (UST) systems, most products currently available are not amenable to AST application. This is due to the long distances and the vast electrically restricted areas typical in AST setting. There now exists a need for innovative AST specific fluid detection technology. An improved method has been developed for continuously monitoring roof drains and the interstitial spaces in double-bottomed ASTs. Additionally, the system is used for conducting bottom water draws and monitors storm water drains. This technique employs fiber optic sensors which can be placed up to 100 meters from their photoelectric controller. Because the sensor system distinguishes between fluids based on the principle of refractive index, the intermittent presence of water does not undermine its function as a fluid detector since watermore » is discerned from various hydrocarbons. This paper describes the evolution of the new methodology, from initial analog prototype to fully digital, commercial implementation in a modern fuel terminal.« less