Unified low-parametrical equation of state for engineering calculations of thermodynamic properties of substances

The new simple semi empirical equation of state for description of P --T data of "normal" substances was specified. New equation of state has 10 individual adjustable coefficients and it describes thermal properties of gas, liquid and fluid in the main with the accuracy within the error of experimental data, except of critical region. The caloric properties and the speed of sound of argon, nitrogen and carbon dioxide were calculated with the help of known thermodynamic equations and in general divergences between calculated and tabular caloric data do not exceed the experimental error. New equation can be used for engineering calculations at the deficit of experimental data, especially on the caloric properties of substances.