  Be stars are thought to be fast rotating stars surrounded by an equatorial
disc. The formation, structure and evolution of the disc are still not well
understood. In the frame of single star models, it is expected that the surface
of an initially fast rotating star can reach its keplerian velocity (critical
velocity). The Geneva stellar evolution code has been recently improved, in
order to obtain some estimates of the total mass loss and of the mechanical
mass loss rates in the equatorial disc during the whole critical rotation
phase. We present here the first results of the computation of a grid of fast
rotating B stars evolving towards the Be phase, and discuss the first estimates
we obtained.
