What You Should Know About Emission Control System
Emission control systems are incorporated into automobiles to control pollution by limiting the amount of exhaust gases released in the air. Exhaust gases from vehicles consist of harmful gases such as carbon dioxide, hydrocarbons, nitrogen oxide and carbon monoxide. Emissions through the tailpipe are measured in parts per million (PPM).
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The exhaust gases can cause great harm to the environment. For emission control to operate effectively, it depends on sensors, vacuum control solenoids and chemical reactions. There are three major sources of noxious gases in a vehicle which are:
- The carburetor and fuel tank
- Engine exhaust
Both the unburned and burned hydrocarbons, phenol carbon monoxide, oxides of sulfur and nitrogen, alcohols and acid are discharged through the exhaust pipes. The crankcase produces hydrocarbons and little carbon monoxide. The carburetor also produces insignificant amount of gases.
Leaked exhaust gases are combined with air in the crankcase. This mixture is then returned to the intake manifold where it is burned in the combustion chamber. Positive crankcase ventilation valves (PVC) is the device responsible for this job.
The emission control system utilizes several components and systems including:
- Catalytic converter
- Exhaust gas recirculation (EGR) Valve
- Filter system
- PVC Valve
- Evaporative system
- Air Injection system
- EGR system
Catalytic converters are located in the exhaust system. It looks like mufflers. It contains platinum or palladium, which act catalysts. They react with exhaust gases to produce carbon dioxide and water which less harmful products. The exhaust should always be clean to ensure the catalytic converter works effectively.
Filter systems consist of oil filter which traps debris and dirt from burned oil. It prevents dirt from entering the intake system. PVC also helps to clean the cranks case. Debris can clog the engine and eventually damage it. Similarly, fuel filters remove debris from the fuel. Another essential part of the fuel emission system is the gas cap. It prevents gases from returning to the fuel tank.
EGR valve allows little amount of exhaust gas to enter the intake system. This lowers the temperature of the combustion chamber by diluting the air-fuel mixture. High temperatures in the combustion system lead to the formation of oxides of nitrogen which is a pollutant. EGR valve is the most effective way to control oxides of nitrogen.
Evaporative system prevents fuel vapor from being released to the environment. The vapor is collected in the carbon canister and redirected to the engine for burning. The system consists of a fuel tank, purge valves, carbon canister and fuel cap.
Air injection system uses an engine driven pump to inject air into the exhaust manifold. Here air mixes with unburned carbon monoxide and hydrocarbons at high temperature. This mixture undergoes combustion. Initially, large amount of unburned gases was released into the atmosphere. The air injection system was invented to address this challenge.
Positive crankcase ventilation (PCV) system
PCV system collects vapor from the normal combustion process and redirects it to the air-fuel mixture intake to be burned during combustion. Vapors dilute air-fuel mixture. PCV valve controls the amount of vapor so that it does not alter engine performance.
Read more about your car’s emission system: