The enthalpy values of important substances can be obtained using commercial software. Practically all relevant material properties can be obtained either in tabular or in graphical form. There are many types of diagrams, such as h – T diagrams, which give the specific enthalpy as function of temperature for various pressures, and h – p diagrams, which give h as function of p for various T. One of the most common diagrams is the temperature–specific entropy diagram ( T – s diagram). It gives the melting curve and saturated liquid and vapor values together with isobars and isenthalps. These diagrams are powerful tools in the hands of the thermal engineer.