Step 3 » GENERAL learning environment Category B (B, B1)

For answer  A 

The catalyst is a device mounted on the engine exhaust manifold, having the role of reducing polluting emissions by transforming the harmful gases resulting from the combustion of the fuel into less harmful substances, such as carbon dioxide and water vapour. It helps to decrease the level of carbon monoxide (CO), nitrogen oxides (NOx) and unburned hydrocarbons (HC), thus contributing to environmental protection.

To reduce atmospheric pollution, modern motor vehicles are compulsorily equipped with catalysts, according to the pollution standards Euro 1, Euro 2, Euro 3, 4, 5, 6 etc., which set strict limits for exhaust gas emissions.

Photo: Catalyst with Emicat heating system
Source: Emitec

1. outer metal casing;
2. electrical connector;
3. heating disc (electrical resistance);
4. fixing pins;
5. metal housing;
6. retaining pins;
7. inner metal casing;
8. catalyst (metal monolith).

For answer  B 

The catalyst does not influence the combustion of the fuel mixture in the engine cylinders. Its function begins after combustion, when the exhaust gases pass through it to be treated and neutralised before being released into the atmosphere.

For answer  C 

The catalyst does not have the role of filtering the fuel before its injection into the cylinders. It acts only on the exhaust gases resulting after the combustion of the fuel mixture, reducing polluting emissions.

The correct answer is: A

Recommendations:

Mechanics course (knowledge of the main components) --> Mechanics course