PETROL

Briefly about gasoline

Gasoline is a product obtained from the refining of crude oil in refineries. Hydrocarbon chains of different lengths are derived, and by combining these chains, different fuels such as gasoline, diesel, kerosene, etc., are produced.

Gasoline was first called “benzine” in Germany. This name is derived from the chemical compound “benzene”. However, in most English-speaking countries, except Canada, the term “petrol” is used to refer to gasoline. The term “gasoline” is mainly used in North America and is commonly referred to as “gas” in colloquial usage. Gasoline, with a density of 0.719 grams per cubic centimeter, is lighter than water and floats on top of it.

Gasoline with different octane ratings (abbreviated as “A”) creates different qualities.

Octane is the resistance to self-ignition or knocking in an engine and has a very high compressibility. Thus, gasoline with a high octane rating is considered good.

Various factors affect the octane rating of gasoline:

1. 1. Elevation above sea level: The higher the elevation, the slower the fuel ignites, similar to having a higher octane number.

2. Humidity and air temperature: Increasing humidity increases the octane rating of gasoline, and decreasing air temperature again increases the octane rating.

3. Other factors: Engine compression ratio, advance and retard of ignition timing, engine operating conditions, engine temperature, etc.

The color of gasoline and its uses:

Petroleum products such as gasoline are all transparent and colorless, similar to water, making it difficult to distinguish them. To differentiate petroleum products more easily, a small amount of specific color is added to each product during the refining and distribution process.

The color of gasoline is a simple additive during the refining process. Red color is primarily used for regular gasoline.

Although using the number obtained from the RON test as the octane rating may not be entirely accurate, in Europe and most countries, including Iran, the RON number is the basis for determining the octane rating of gasoline.

(In the United States, using the formula (RON + MON) / 2 yields a new number called PON or Pump Octane Number. This somewhat solves this problem.)

Temperature, elevation, and humidity’s impact on the octane rating:

Changing environmental conditions can increase or decrease the octane rating of gasoline.

One of these cases is elevation, where the octane rating for each gasoline is determined based on a test performed at sea level. The higher the test is conducted (assuming other parameters remain constant), the better the octane rating will be.

For example, if we transfer a car with gasoline that has an octane rating of 82 (at sea level) to a location 1000 meters above sea level (assuming the same temperature and humidity), we will see that the engine of this car will be much less prone to knocking at an altitude of 100 meters compared to the sea level.

(Approximately up to 1800 meters above sea level, for every 300 meters increase in elevation, 1.4 is added to the octane rating RON, and at an elevation above 1800 meters, this value is converted to 2.5 for every 300 meters increase in elevation.)

However, elevation is not the only atmospheric factor affecting the octane rating, and humidity and air temperature are also other influential atmospheric factors. Adding 1 gram of water to each kilogram of dry air increases the MON octane rating by 0.25 to 0.32, and reducing the ambient temperature by every 5.6 degrees Celsius also increases the MON octane rating by 0.44 to 0.55. So, in winter, lower octane is required compared to summer, given similar conditions in terms of humidity and test location.

Since the effect of elevation on octane is much greater than the effect of humidity and temperature, if gasoline suppliers also provide higher octane for coastal regions (north and south), car repairs in these areas will be delayed due to the use of higher octane. Other factors that affect the octane rating include the engine’s compression ratio, advance and retard of ignition timing, engine operating conditions, engine temperature, air-fuel ratio, and similar factors.