Sintered metal porous media are currently used to replace conventional orifices as restrictors in air-bearing systems. The flow properties in porous media are generally approximated by Darcy and Forchheimer regimes in different flow regions. In this study, an ISO expanded expression is proven defective when it is used to represent flow properties through porous media under slight pressure drops ( kPa). A modified Forchheimer equation is therefore developed to correlate the pressure drop with flow rate, including compressibility and inertial effects. Experimental and theoretical investigations on pressure drop characteristics are conducted with a series of metal-sintered porous media. Permeability is first determined in a strict Darcy region with , followed by the inertial coefficient with , rather than determining these two simultaneously. The theoretical mass flow rate in terms of the modified Forchheimer equation provides close approximations to the experimental data.