  We investigate the phase diagram of a three-dimensional associating gas
$(ALG)$ model. This model combines orientational ice-like interactions and
``van der Waals'' that might be repulsive, representing, in this case, a
penalty for distortion of hydrogen bonds. These interactions can be interpreted
as two competing distances making the connection between this model and
continuous isotropic soft-core potentials. We present Monte Carlo studies of
the $ALG$ model showing the presence of two liquid phase, two critical points
and A density anomaly.
