Pressure drops were determined in fluid flow through SMX Suizer static mixer of different sizes. In order to investigate a large range of Reynolds number, the experiments were performed with fluids of different viscosities. Pressure drops measurements in static mixer considered as a porous medium, are analysed with a capillary model for the determination of the geometric parameters of static mixers: pore diameter and tortuosity. These parameters allow the expression of pressure drops in terms of friction factor, f(C), as a function of pore Reynolds number, Re-p. A universal equation is obtained for the friction factor: f(C) = 16/Re-p + 0.194 which covers both viscous and inertial flow regimes.