Pressure losses in Venturi pipes, their rational forms and coefficients of local resistance

The developed self-regulating devices for the protection of solar water heaters from freezing provide more economical and reliable control of solar heating systems compared to other automation tools. For practical calculations of the solar circuit, the most convenient form of representation of the characteristics of Venturi tubes are criterial equations. Equations summarizing the experimental data on small-sized Venturi pipes are valid in the region of viscous resistance at the degree of flow constriction.