  Finite temperature Hartree-Fock-Bogoliubov calculations are performed in Sn
isotopes using Skyrme and zero-range, density-dependent pairing interactions.
For both stable and very neutron-rich nuclei the critical temperature at which
pairing correlations vanish is independent of the volume/surface nature of the
pairing interaction. The value of the critical temperature follows
approximatively the empirical rule T$_c$ $\simeq$ 0.5 $\Delta_{T=0}$ for all
the calculated isotopes, showing that the critical temperature could be deduced
from the pairing gap at zero temperature. On the other hand, the pairing gap at
temperatures just below T$_c$ is strongly sensitive to the volume/surface
nature of the pairing interaction.
