Emissions Inspector Certification Flash Cards

air pollution - the contamination of the atmosphere by the introduction of pollutants from human and natural sources United States Environmental Protection Agency (EPA) - Estimated that 20% of all US pollution comes from cars and trucks Major pollutants from vehicles - Hydrocarbons (HCs), Carbon Monoxide (CO), Nitrogen Oxides (NOx). Other pollutants includes Sulfur Dioxide (SO2) and Particulate Matter. Hydrocarbons - Principal constituents of gasoline, diesal, and natural gas. Excessive amounts of this pollutant is mainly from incomplete combustion and rich fuel mixtures. Tends to stay consistent with the stoichiometric ratio. Nitrogen Oxides - Forms with HC to create smog; mainly formed in vehicle engines during combustion of fuel at high temperatures. Primary cause of acid rain Oxygen - Too much or too little is bad and can cause improper combustion. Too little can be from rich air-fuel mixture, and dirty air filters. Too much can be caused by lean air-fuel mixture or engine misfires. Ozone(Smog) - Not emitted directly into the air, but created at ground level by chemical reactions from NOx and HC. Also known as smog. Particulates - This matter is released into the air by combustion and can damage the lungs and cause health problems Five Gas Theory - Shows how the ratio of each gas to the others changes in response to different temperatures and fuel mixtures Lean Mixture - Low ratio of fuel to air Rich Mixture - High fuel ratio to air Stoichiometric Ratio - A mixture of approximately 14.7(air) to a single part of fuel *14.7/1* to produce the most efficient use of fuel and the lowest emissions Carbon Monoxide - Colorless and odorless; a poisonous gas produced by incomplete burning of fuel. Carbon Dioxide - Best lean indicator for air-fuel ratio and a desirable component of exhaust.