New parameters of the linear isotherm regularity, the so-called LIR equation of state, are used to calculate the thermal pressure coefficient of dense fluids. The extent of the deviation between real thermal pressure coefficients and thermal pressure coefficients by applying LIR are best expressed through the use of new parameters in LIR. In this paper, the temperature dependence of LIR parameters in the form of a first order have been developed to second order and third order, and the temperature derivatives of new parameters are used to calculate thermal pressure coefficients. The resulting model accurately predicts thermal pressure coefficients from the lower density limit at the Boyle density and from the triple temperature up to about double the Boyle temperature. The upper density limit appears to be reached at 1.4 times the Boyle density. These problems have led us to try to establish a function for accurate calculation of the thermal pressure coefficients, based on LIR theory for different fluids.