For a long time, mankind has been trying to find a simple and easy to use source of heat, light and fuel. At first, firewood and ordinary straw acted as such; later, a person learned to extract and use peat. Then mankind made a significant breakthrough in the scientific and technical field as a whole - and in the fuel sector in particular, by starting to use kerosene.
It is a mixture of hydrocarbons boiling at a temperature of 150-250 ° C. It is a clear, oily, combustible liquid obtained by distillation of oil. Depending on the processing method and chemical composition, kerosene may contain saturated aliphatic hydrocarbons , naphthenic compounds, bicyclic compounds, various impurities of oxygen, sulfur or nitrogen elements.
The main stage in the use of household kerosene is associated with the invention in 1823 of an oil refinery. And starting in 1950, when turboprop and jet aviation began to develop actively, the production of another type of it, called "aviation kerosene," began. Both types of kerosene are obtained by distillation of oil. During the initial processing, oil is purified from various impurities and water (it is worth noting that the density of kerosene is less than the density of water). Then, the already purified composition is subjected to direct distillation, during which hydrocarbons are boiled off, an oil fraction and a residue in the form of fuel oil are released.
On average, the density of kerosene is about 0.78-0.85 g per one cubic centimeter, and the flash point varies from 28 to 72 ° C. The density of the combustible liquid used for domestic purposes is 830 kg per cubic meter, and its flash point is about 35-40 ° C. These are the most common indicators. The density of kerosene used for lighting in mines and on small vessels is 860 kg per cubic meter. The flash point of this type of liquid can be up to 90 ° C. The density of aviation kerosene is at least 780 kg per cubic meter. Such kerosene is intended for use in flying subsonic aircraft.
By kerosene density is meant a value that is determined by the ratio of the mass of this type of fuel to its volume. The density of a given flammable liquid is determined using a pycnometer - a device specially designed to determine the density of various liquid and solid bodies.
The analysis requires a pycnometer, a thermostat capable of maintaining a temperature of 20 ° C, a vacuum pump, a vacuum desiccator, a thermometer and kerosene. The procedure for calculating its density is divided into several main stages. First, the washed and dried pycnometer is weighed carefully. Then graphite is poured into it and weighed again. Then kerosene is poured into the flask (up to half the volume) and placed in a desiccator, where it is kept for about one hour.
At the second stage of the analysis, the pycnometer, taken out of the desiccator and completely filled with kerosene, is placed for one hour in a thermostat. After a certain period of time, the device is removed from the thermostat and its weight is determined. Then, in the same pycnometer, but already well washed and wiped dry, they pour kerosene and do the same thing, but only without adding graphite. Similar actions are carried out by pouring ordinary distilled water into the pycnometer.
The density of kerosene is calculated by the following formula: the density of water is multiplied by the mass difference of the pycnometer with kerosene and graphite and the mass of an absolutely empty pycnometer, and the result is divided by the difference of the mass of the pycnometer with water and the mass of the empty pycnometer.
The discrepancy allowed between the results of two parallel determinations should not be more than 0.01-0.02 g / cm.