(Simply Called Petrol)
Motor gasoline is meant a mixture of the lighter fractions of petroleum composed of hydrocarbons having boiling points in the range approximately 30 0C to 215 0C. Straighfluidizet run stream from Crude Distillation Unit (CDU) and cracked stream from d Catalytic Cracker Unit (FCCU) with the above boiling range are blended to obtain required quality Motor Gasoline. It may contain small quantities of chemical e.g. tetraethyl lead, etc. added to improve its performance.
Motor spirit, Petrol and Gasoline are different nomenclatures for the same product. Motor spirit is of British origin while Gasoline is of American origin.
SPECIFICATIONS
Motor gasoline are currently marketed meeting Bureau of Indian Standards Specification, IS : 2796-1971, for Motor Gasoline 87 and 93 Octane. Besides Motor Gasoline (MT 80) is marketed as defense applications.
The most important property of a gasoline is its Octane Number, (ON), which indicates whether the fuel will knock in an engine. Knock or "Pink" is the audible explosion (detonation) produced when a portion of the fuel charge in the cylinder ignites spontaneously ahead of the normal flame front. All things being equal, knock is a direct function of the fuel alone, some fuels being more prone to it than others. It is determined in the CFR (Co-operative Fuel Research) engine and is defined as the percentage of iso-octane, arbitrarily given an O.N. of 100, in a blen with normal heptane (O.N.=0) which matches the fuel under examination.
Motor gasoline is normally rated in the CFR engines under two sets of conditions which differ in severity. The Research or F.1 method gives a rating more applicable to operation under mild conditions, while the Motor or F.2 method may be a better criterion when operating at higher speeds and loads.
The higher the compression ration of an engine the higher is its thermal efficiency. The limiting compression ration that can be utilized is set by the anti-knock characteristics of the fuel; thus increasing of the octane number permits the use of higher compression rations and gives more power, higher efficiency and lower fuel consumption. However, no advantage is gained by increasing the octane number beyond that necessary to give knock free performance.
The CFR octane number is a rating on one particular type of engine under a given set of conditions and cannot by itself be used to predict the road octane number (RON) of the fuel under varying conditions of operations.
IS- 2796-1971 SPECIFICATION OF MS (INDIA)
| No. | Characteristics | Test Method | 87 Octane | 93 Octane |
| 1 | Colour, Visual | - | Orange | Red |
| 2 | Copper Strip Corrosion for 3 hours at 50 0C | P-15 | Not worse than No.1 | |
| 3 | Density at 15 0C g/ml | P-16 | 0.730 | 0.735 |
| 4 | Distillation | | | |
| | Initial boiling point 0C | | 50 | 45 |
| | Recovery upto 75 0C,%v,min. | | 10 | 10 |
| | Recovery upto 125 0C,%v,min. | | 50 | 50 |
| | Recovery upto 180 0C,%v,min. | | 90 | 90 |
| | Final boiling point 0C, Max | | 2 | 2 |
| 5 | Octane Number (research Method) | P-27 | 87 | 93 |
| 6 | Oxidation stability in Minutes, min. | P-28 | 360 | 360 |
| 7 | Residue on evaporation, mg/100 ml, max. | P-29 | 4.0 | 4.0 |
| 8 | Sulphur, % wt.max. | P-34 | 0.25 | 0.20 |
| 9 | Lead content, g/lmax | P-38 or 82 | 0.56 | 0.80 |
| 10 | Reid vapour pressure at 38 0C kgf/cm2, max | P-39 | 0.70 | 0.70 |
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