3.1 Reid Vapor Pressure (57)

Volatility is defined as the tendency or ability of a material to change from a liquid state to a gaseous state. This property is extremely important since the combustion process takes place in a gaseous environment, inside the engine, where the gasoline must first vaporize so that combustion can occur. Gasoline contains hundreds of compounds, each having a boiling point that interferes with the others when mixed. The volatility of gasoline compositions is determined based on the properties of Reid vapor pressure and the distillation curve (57).

3.1.1 Reid Vapor Pressure
The vapor pressure of gasoline is a fundamental physicochemical property to the level of emission of volatile compounds in the gasoline supply system and in the combustion process, especially in starting the
The pressure exerted by gasoline vapors in a confined space, which is measured at 37.80C, is called Reid vapor pressure. RVP has a great influence on evaporative hydrocarbon emissions from the fuel tank of all vehicles. In addition to these, a maximum increase of RVP occurs with 5%-10% addition of all oxygenates. Adding oxygenates into gasoline cause an increase in vapor pressure and depresses the boiling temperature. Also, higher RVP values can because of the vapor lock and higher evaporative harmful emissions. That’s why, RVP was limited more countries with federal legislations (59). The typical oil industry process of adjustment of the Reid Vapor Pressure in the final blend is the addition of butanes from the gases separated initially from the crude oil. The addition of butanes also will help the octane rating, as butane has a high octane number. Because butane is so volatile, it accounts for 75 percent of the vapor pressure of gasoline (60). Ethanol, long-chain alcohols, and several oxygenates that might be derived from cellulosic biomass were blended into three seasonal gasoline blend stocks, and