Coaxial vapor flow indicator with pump speed control

Abstract

A vacuum assist vapor recovery system for a fuel dispensing system having a coaxial hose with an outer fuel conduit for delivery of fuel and an inner vapor conduit for recovery of vapor, and such a fuel dispensing system includes an indicator assembly for providing indication of vapor flow reduction in the inner vapor conduit. The indicator assembly has a detector element in communication with the inner vapor conduit for detection of vapor flow within the inner vapor conduit and an indicator element of vapor flow for indication of vapor flow and vapor flow reduction within the inner vapor conduit detected by the detector element. The detector element includes a Venturi device disposed in communication with the inner vapor conduit, a diaphragm responsive to the pressure between the Venturi throat and the upstream inner vapor passageway, and a magnet associated with, i.e., reflecting the movement of, the diaphragm. The indicator element consists of a signal indicative of the vapor flow rate from a Hall Effect device.

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