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AIR POLLUTION & EVAPORATIVE EMISSIONS

AIR POLLUTION & EVAPORATIVE EMISSIONS. Hydrocarbons. Unburned fuel vapors When exposed to sunlight, chemical reaction occurs that produces ground-level ozone O3. Harmful to all living things Vehicle emissions create 50% of this ozone. Carbon Monoxide. Colorless, odorless, toxic gas

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AIR POLLUTION & EVAPORATIVE EMISSIONS

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  1. AIR POLLUTION & EVAPORATIVE EMISSIONS

  2. Hydrocarbons • Unburned fuel vapors • When exposed to sunlight, chemical reaction occurs that produces ground-level ozone O3. • Harmful to all living things • Vehicle emissions create 50% of this ozone

  3. Carbon Monoxide • Colorless, odorless, toxic gas • Product of incomplete combustion • Displaces oxygen which reduces oxygen in bloodstream • Vehicles produce 2/3’s of co in atmosphere

  4. Carbon Dioxide • Product of proper combustion • Does not directly impair human health • Greenhouse gas • Traps heat • Helping to increase global warming

  5. Just What is Ozone? • Ozone is a form of oxygen with a different chemical property • Ozone differs from oxygen: • Has a distinctive odor • Contains 3 oxygen atoms • Absorbs damaging ultraviolet (UV) radiation • In large concentrations ozone is hazardous

  6. Earth’s Atmosphere • Troposphere start on the surface and extends 5 – 9 miles • Air most dense • All weather occurs is this region • Stratosphereextends for 31 miles • Contains the Ozone layer

  7. Good Ozone • Blocks or absorbs most of the suns ultraviolet rays • Approx. 3,000 million tons of ozone in atmosphere • If concentrated at sea level, would measure only 3 mm thick

  8. Bad Ozone (Smog) • Brown haze seen on hot summer days • Result from burning fossil fuels – chemical reaction from heat & sun light • Health problems • Aggravates heart, lung ailments • Can lower immune system • Eye & nose irritations • Environmental problems • Inhibits plant growth, weakens plants • Reduce yields • Deteriorates man-made materials • Acid rain

  9. Evaporative EmissionsHydrocarbons escaping through fuel evaporation. • Diurnal – gas evaporation as daytime temps increase • Running Loss – vaporization from hot engine & exhaust parts • Hot Soak – hot engines (off), vaporization can continue • Refueling – Vapors forced out of tank as liquid fuel enters

  10. Evap. Emission Control Systems • Sealed fuel tank – domed to allow for vapor expansion • Liquid-vapor separator – when tank is full fuel can enter vent lines • Vent lines – routes vapor to canister & engine • Activated charcoal canister – absorbs fuel vapors, releases vapors with fresh air • Non venting gas cap – pressure/vacuum relief valve

  11. Carbon Canister • Holds vapors when engine not running • Engine fully warm & off idle, canister is “purged” allowing fresh air in, fuel vapors routed to engine & burned

  12. Canister Operation

  13. Purge Valve • Normally closed • Vacuum or electric solenoid • Engine off or idling valve is closed • Engine running valve opens allowing purge of canister • Solenoids either on/off or PWM

  14. Basic Purge Operation

  15. Thermostatic Vacuum Switch (TVS) • Installed in intake manifold coolant passage • Valve opens @ 115 F, allows vacuum to flow

  16. Canister Venting • Open bottom – When purging fresh air enters from bottom of canister • Closed bottom – fresh air enters for clean side of air filter • Electric vent solenoid – PCM controlled, allows fresh air in when commanded, seals system when closed.

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