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