module 2: chemical and physical characteristics of ethanol and hydrocarbon fuels

Module 2: Chemical and Physical Characteristics of Ethanol and

Hydrocarbon Fuels

2

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.

3

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

4

Activity 2.1 — Definitions

Purpose:– To allow participants to identify the

definitions related to ethanol.

5

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)

6


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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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

8

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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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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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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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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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

14

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.

15

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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Gasoline floating on layer of ethanol / water solution– Resulting ethanol / water solution still

flammable

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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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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

module 2: chemical and physical characteristics of ethanol and hydrocarbon fuels

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