Status Report on Control of Gasoline Vapor Losses from Station and Vehicle Filling

Abstract

This paper is one of a series covering the major elements of EQL Strategy #1, for the reduction of air pollution in the South Coast Air Basin. It discusses the control of one of the largest uncontrolled stationary sources of hydrocarbons, namely, the displaced gasoline vapors from the filling of tanks in gasoline stations and motor vehicles. Progress in this area has been very rapid in the last year, since the San Diego A. P. C. D. adopted its Rule 63 (on January 17. 1972) requiring control of this source. This paper is an attempt to summarize the situation briefly as it appears at present, indicating the state of the control technology at the present time, what its likely costs will be, and what are the essential features of the regulations that have been promulgated for control of this source. For the South Coast Air Basin, it is estimated that about 65 tons/day could be eliminated by controlling the gasoline vapor losses involved in gasoline marketing, as compared with a total of 210 tons/day of reactive hydrocarbon emissions from stationary sources projected for 1975. It should be pointed out that the process occurs in two steps. The first step is when the tank truck refills the underground storage tank at the gasoline station. As the gasoline liquid fills the storage tank, the vapor-laden air above the liquid is pushed out the vent pipe into the atmosphere. The incoming gasoline is piped into the tank via a "submerged" fill line, which reduces the vapor losses about 40% over "splash" fill by minimizing the vapor-liquid interface area. However, about one third of the 65 tons/day till comes from this transfer. The second transfer of gasoline occurs in filling the vehicle. Here, filling is essentially "splash" -- the incoming gasoline coming into contact with the outgoing vapor. This source contributes the other 2/3 of the total emissions of 65 tons/day.