The flow discharge coefficient of tuyere gas distributors with six radial holes was obtained as a function of the tuyere head holes diameter Reynolds number, with the holes to riser flow cross-sectional area ratio as parameter. The fraction of the pressure drop which occurred in the tuyere head holes, a significant parameter for satisfactory operation of a fluidized bed, was also determined. The flow phenomena in the thin-plate standard square-edged orifice meter and in the tuyere discharge holes were studied; the differences in the corresponding discharge coefficient values are discussed in the light of the flow pattern dissimilarities. The possibility of adopting the standard thin-plate square-edged orifice meter or perforated-plate discharge coefficients to calculate the tuyere coefficient was analyzed, as well as the influence of the presence or absence of a solids fluidized bed over the distributor plate.