Gasoline is a quite complex mixture of hydrocarbons which consists of around 200-300 different compounds with boiling temperatures ranging from 30oC to 215oC. This mixture also contains components with lower boiling points however their content in marketable gasoline is limited by such quality parameters as saturated vapor pressure. However the composition of gasoline is far less important to the driver and user than its performance characteristics. Gasoline is subject to a variety of quality indicators. Actual values of quality parameters are specified in quality certificate which is issued for every batch shipped from the refinery.
Quality indicators could be relatively grouped as follows:
- performance – octane number, distillation characteristics, oxidation stability, copper strip corrosion test;
- environmental – sulphur content, aromatics, benzene content;
- important for storage and transportation – gum content, saturated vapor pressure (volatility);
- required for (re)calculation of components or additives - density, oxygen, ethanol content, etc.
Starting from 2007, gasoline supplied to Lithuanian market is blended with denatured ethanol of biological origin. Ethanol is added in order to meet EU commitments regarding use of fuels produced from renewable sources. Ethanol also has high octane number however due to higher volatility rate its use in gasolines is limited as excess quantities lead to losses in storage and problems in fuel feeding system.
Main technical parameters of gasoline
It really does matter what fuel you put in your vehicle. Depending on the type of gasoline, your engine may run with upsets or demonstrate high performance.
Octane number. Octane number of gasoline is a measure of its resistance to knock. Knocking referred to as detonation is premature and spontaneous ignition of fuel charge when it explodes rather than burns resulting in incomplete combustion. Resistance to knocking is expressed in octane number. There are two types of octane rating: MON (motor octane number) which is determined by running the fuel in a test engine at speed normal for driving in cities and RON (research octane number) which is determined running the engine at speed normal in highways. The higher the octane number, the more compression the fuel can withstand before detonating therefore fuels with a higher octane rating are used in high performance gasoline engines that require higher compression ratios. According to octane number, gasolines are grouped into grades. For example, grade 95 means that resistance of gasoline to detonation is not lower than 95.
Since 1995, ORLEN Lietuva replaced TEL (tetra-ethyl-lead) which was used as octane booster with such components as MTBE, isomerizate, oligomerizate, alkylate or high-octane hydrocarbon mixtures. It should be noted that such gasolines are not suitable for prolonged storage in non-tight containers as MTBE and alkylate have low boiling temperatures (below 0 oC) and these components evaporate in long storage. All gasolines produced by ORLEN Lietuva are unleaded and are in full compliance with EU standards.
Corrosion activity. It means the speed of chemical reactions between gasoline, combustion products and materials the entire system of circulation from feed and combustion to exhaust is made of. Corrosion activity is determined by copper strip corrosion test. In this test, a polished copper strip is suspended in 50oC gasoline for three hours and its effect observed. Corrosion activity is rated according to the change of color of copper strip. Copper in corrosion changes its color so the results of test are obtained by visual comparison of the color of strip to standard color chart. This test assesses the relative degree of corrosiveness.
Corrosion activity depends on the acidity of gasoline, total suphur, mercaptan sulphur, acids and alkalis soluble in water it contains. ORLEN Lietuva produces 10 ppm sulphur specification gasolines. They are in full compliance with EU standards. Actual content of sulphur compounds does not exceed 8 ppm. According to EU requirements, from 1 January 2009 the content of sulphur compounds in gasolines cannot exceed 10 ppm.
European standard gasoline
With introduction of more stringent market requirements, the quality of petroleum products becomes more and more indispensable to the users. ORLEN Lietuva produces and places on the market only highest-quality gasolines in full compliance with EU requirements.
Sulphur content in all types of fuel is reduced due to environmental concerns. When fuel is burned sulphur combines with oxygen (SO2 and SO3) to create emissions that lead to acidification of aquatic systems and soil and increased corrosion rate of metals.
Gasoline with multifunctional additives VERVA
Even gasoline of very good quality leaves built-up scale when burning. To remove it multifunctional additives are used. They are added just before the fuel is provided to the user. This additive improves washing properties of fuel keeping cylinders, pistons, rings, valves and entire fuel feed system, starting from the tank of vehicle, clean. Multifunctional additives improve fuel combustion in cylinders hence fuel consumption drops down by up to 2.5 percent. They form anti-corrosive film in fuel system of engine, remove water from the system and protect filters against plugging which is especially important in winter.
Gasoline with multifunctional additives produced by ORLEN Lietuva has its special tradename VERVA. This gasoline improves engine performance and lowers harmful atmospheric emissions.
ORLEN Lietuva has long experience in production of gasolines with multifunctional additives. Earlier these gasolines were sold under the tradename VENTUS.