Fuels

Petrol

Petrol is a transparent, green, volatile, flammable liquid consisting of a mixture of hydrocarbons obtained by refining crude oil; the green colour derives from a deliberate colouring required by the authorities as a guarantee against potential frauds. The petrol responds to a European specification, EN 228, which also establishes limits for the protection of the environment (content of sulphur, benzene and aromatics).

Principal characteristics and performance:

  • the anti-knocking potential (the octane number);
  • volatility;
  • density.

The requested performances are:

  • easy engine start at all temperatures;
  • rapid engine warming;
  • smooth running of the engine in all driving conditions;
  • compressive strength, ie absence of premature detonations during combustion.

Diesel

Another product obtained from the primary distillation of crude oil is diesel.

Its quality is influenced by the characteristics of the crude oil from which it originates and the production techniques used (cracking, visbreaking, etc...).

Diesel fuel, for a long time used almost exclusively in heavy vehicles, is undergoing increasing expansion in Italy and around the world where the car fleet has gradually switched to diesel thanks to the development of turbo-diesel engines, often equipped with the modern CommonRail: as well as being cheaper than petrol, diesel assures better specific fuel consumption and higher torque values.

Diesel fuel is a product used to power compression ignition engines (diesel engines): it responds to a European specification, EN 590, which, in particular, also establishes environmental protection levels (sulphur and aromatic content) .

The cetane number
this is a measure of the combustion speed of diesel oil. It influences the cold start of the engine and the combustion characteristics, namely efficiency, noise and smokiness.

Cloud point
This represents the temperature at which crystals of paraffin begin to form in diesel fuel.

Cold filterability
This is an estimate of the minimum operating temperature of a diesel-powered vehicle.

The level of water and sediment
These are indices of impurities found in diesel fuel. If they exceed the limits, these indices reveal contamination of the product or (as regards sediments) also of phenomena of instability.

Stability
This is the capacity of diesel not to form sediments during storage. Excessive instability can lead to the formation of gums and mucilage which can cause the filtering of the feeding systems to clog.

We now provide a useful list concerning diesel performance.

  • Good engine performance both in fast diesel engines (cars), in heavy diesel engines (trucks), and in diesel engines mounted on agricultural vehicles and earth-moving vehicles.

  • Low consumption and low noise.

  • Smoke and polluting emissions within the limits set by the regulations.

  • Good cold start.

  • Operability at low temperatures.

Here we summarise the most frequent drawbacks of diesel.

  • Dirtying of the injectors and consequent greater noise, higher consumption and smokiness.

  • Difficulty starting at low temperatures.

  • Blocking of filters reducing the flow of diesel fuel through the fuel system due to the presence of paraffin, organic or inorganic sediments.

  • Deterioration of quality after very long storage periods.

  • Formation of sediment and gums.

Liquefied petroleum gas (LPG)

This is a mixture of light petroleum fractions (propane and butane), obtained in the refining process, which have the property of being gaseous at atmospheric pressure and ambient temperature but of becoming liquid under light pressure.

LPG is used in combustion and carburation; the fact that, at time of use, it is in a gaseous form enables an excellent mixing with air, making for more efficient combustion, reduction of consumption and of emissions of polluting compounds.

Used as fuel, this product complies with the limits set by European standard EN 589.