1. Octane Number: This is the most important measure of petrol quality. It reflects the fuel's resistance to knocking or detonation in an engine. Higher octane numbers indicate a higher resistance to knocking. It is measured using the Research Octane Number (RON) and Motor Octane Number (MON).
2. Sulfur Content: This measures the amount of sulfur impurities in the fuel. Lower sulfur content is better for both engine performance and the environment.
3. Reid Vapor Pressure (RVP): This measures the fuel's volatility, indicating how easily it evaporates at a given temperature. RVP is particularly important for hot climates, where high volatility can lead to vapor lock.
4. Distillation Curve: This measures the boiling point range of the fuel, indicating its different components and their respective volatility.
5. Cetane Number: This is a measure of the fuel's ignition quality, relevant for diesel fuels but not petrol.
6. Water Content: Water contamination can harm engine performance, so its presence is also measured.
7. Additives: Many additives are added to petrol to improve its performance or reduce emissions. These include detergents, anti-knock agents, and corrosion inhibitors.
Note: While these parameters help gauge the quality of petrol, they don't directly reflect its purity. Purity is usually measured in terms of the percentage of specific hydrocarbon compounds in the mixture. However, this is less relevant for the general consumer and is primarily used in research and industrial applications.
