Reliability observations and emission measurements at gasoline transfer vapor recovery systems

A 5 wk study was performed to assess the reliability of vapor control systems at gasoline service stations and to measure gasoline vapor concentrations at various emission points of the systems. The study consisted of random and unannounced inspections of gasoline vapor recovery devices at filling stations in the San Diego area. Five secondary vapor recovery systems were reviewed at 23 locations, as well as two displacement (balanced) vapor recovery systems. The 23 vacuum assisted vapor recovery systems were inoperative 5.4% of the time during the test period. Most of the breakdowns were the results of the failure of a small high speed blower belt. Several of the vapor recovery units were found to have vapor leaks which would significantly lower their efficiency. Appreciable leakage was noted at the nozzle-filler neck interface with all systems. The major causes of this leakage appeared to be the lack of a tight seal at the nozzle-filler neck interface, of insufficient applied vacuum to compensate for the pressure buildup in the vehicle tank caused by the liquid flowing into it. A number of potential fire and safety hazards were noted during the test period. Requirement of flame and waterproof circuitry, pressure tested piping, andmore » specific foundation material would remedy most of the deficiencies.« less