Experimental investigations of isothermal steady flows for various gases have been carried out in a silica micro tube. This study is focused on the mass flow rate measurements of these flows in slip regime using a suitable powerful platform. First we analyse, for each gas, the pertinence of a first or second order continuum treatment ; then we deduce from experiments, using the appropriate treatment, the tangential momentum accommodation coefficient (TMAC) of each gas. The TMAC obtained for the various pairs of gas (nitrogen, argon, helium)/surface (fused silica) exclude a full diffuse reflection.