Module 2: Chemical and Physical Characteristics of Ethanol and
Hydrocarbon Fuels
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Objective
Upon the successful completion of this module, participants will be able to describe the chemical and physical differences between pure gasoline and gasoline / ethanol blends.
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Introduction
Characteristics of polar solvents & hydrocarbons, their differences, & how they interact
Conditions under which ethanol-blended fuels will retain certain characteristics of types of fuel
Help emergency responders mitigate various incidents according to conditions found
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Activity 2.1 — Definitions
Purpose:– To allow participants to identify the
definitions related to ethanol.
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Characteristics of Gasoline (A Hydrocarbon)
Similar characteristics whether flammable / combustible liquids
Produced from crude oil by fractional distillation
Non-water miscible / insoluble Flash point -45°F (depending on
octane rating)
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Characteristics of Gasoline (A Hydrocarbon)
Vapor density between 3 & 4:– Gasoline vapors seek low levels / remain
close to ground level Specific gravity of 0.72–0.76:
– Will float on top of water Auto-ignition temperature between
536°F & 853°F Boiling point between 100°F & 400°F
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Characteristics of Gasoline (A Hydrocarbon)
Not considered poisonous:– Harmful effects after long-term &
high-level exposure– Can lead to respiratory failure
Smoke from burning gasoline is black & has toxic components
Greatest hazard is flammability:– Fairly narrow range of flammability
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Characteristics of Ethanol (A Polar Solvent)
Ethanol used with motor fuels denatured with up to 5% gasoline / similar hydrocarbon for transport
Denaturant has minimal effects on characteristics
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Characteristics of Ethanol (A Polar Solvent)
Renewable fuel source produced by fermentation & distillation process
Most common source in U.S. in 2008 is corn
Polar solvent Water-soluble Flash point 55°F
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Characteristics of Ethanol (A Polar Solvent)
Vapor density of 1.59:– Heavier than air– Vapors do not rise
Specific gravity 0.79:– Lighter than water – Thoroughly mix with water
Auto-ignition temperature 793°F
Miscibility
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Figure 1Figure 2
Figure 3
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Characteristics of Ethanol (A Polar Solvent)
Boiling point 173°F Less toxic than gasoline / methanol Carcinogenic compounds not present
in pure ethanol Greatest hazard as motor fuel
component is flammability:– Wider flammable range than gasoline
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Characteristics of Ethanol (A Polar Solvent)
In pure form no visible smoke & hard-to-see blue flame
In denatured form little to no smoke & slight orange flame may be visible
Ethanol & some ethanol blends can conduct electricity
Large amounts of water required to dilute ethanol to no longer support combustion
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Activity 2.2 — Comparison of Gasoline and Ethanol
Purpose:– To allow participants to discuss the
differences & similarities in the chemical & physical properties of ethanol & gasoline.
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Characteristics of Ethanol-Blended Fuels
Ethanol increases heat output of unleaded gasoline:– Lower emissions from unburned
hydrocarbons Minimal amounts of water will draw
ethanol out of blend away from gasoline:– Ethanol & gasoline more suspension
than solution
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Characteristics of Ethanol-Blended Fuels
Gasoline floating on layer of ethanol / water solution– Resulting ethanol / water solution still
flammable
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Characteristics of Ethanol-Blended Fuels
Blending fuels alters physical & chemical characteristics of original fuels:– Visual difference of smoke & flame
characteristics: Higher content of ethanol, less visible black
smoke content & orange flame production
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Characteristics of Ethanol-Blended Fuels
Blending fuels alters physical & chemical characteristics of original fuels:– When foam / water flowed on burning
product, gasoline tends to burn off first: May have no visible flame or smoke
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Summary
Polar solvent water-soluble & flammable When blended with gasoline, produces
slightly cleaner burn than gasoline alone Blend of gasoline & ethanol can easily go
unnoticed by emergency responders:– Ethanol will be last fuel to burn – Ethanol will burn without visible smoke / flame
