VAPOR RECOVERY SYSTEM UTILIZING A FIBER-OPTIC SENSOR TO DETECT HYDROCARBON EMISSIONS

摘要

A method and apparatus is disclosed for sensing hydrocarbon in the vapor path of fuel dispensers using a fiber-optic sensor. The sensor includes an absorber-expander sensing structure mechanically coupled to the fiber body and responsive to the presence of effluent fuel components for absorbing the hydrocarbon therein and expanding in response thereto. The expansion activity has the effect of generating a microbend deformation in the fiber, producing detectable changes in the optical throughput representing the concentration of hydrocarbon that is sensed by the absorber-expander element. The fiber-optic sensor is particularly useful in a vapor recovery system by providing an optical signal that is representative of the ambient hydrocarbon concentration. The concentration level of hydrocarbon represented by the detected change in fiber transmittance serves as the basis for regulating the rate at which the vapor pump collects effluent vapors discharged during refueling, namely by appropriately adjusting the vapor pump operating speed.