The new simple semiempirical equation of state (EoS) for the description of P-rho-T data of "normal" substances was specified. The new EoS has eight individual adjustable coefficients, and it describes the thermal properties of gas, liquid, and fluid with an accuracy within the error of experimental data, except for the 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. The new equation can be used for engineering calculations at the deficit of experimental data, especially on the caloric properties of substances.