  The equation of state of hadron resonance gas at finite temperature and
baryon density is calculated taking into account finite-size effects within the
excluded volume model. Contributions of known hadrons with masses up to 2 GeV
are included in the zero-width approximation. Special attention is paid to the
role of strange hadrons in the system with zero total strangeness. A density-
dependent mean field is added to guarantee that the nuclear matter has a
saturation point and a liquid-gas phase transition. The deconfined phase is
described by the bag model with lowest order perturbative corrections. The
phase transition boundary is found by using the Gibbs conditions with the
strangeness neutrality constraint. The sensitivity of the phase diagram to the
hadronic excluded volume and to the parametrization of the mean-field is
investigated. The possibility of strangeness-antistrangeness separation in the
mixed phase is analyzed. It is demonstrated that the peaks in the kaon to pion
and lambda to pion multiplicity ratios can be explained by a nonmonotonous
behavior of the strangeness fugacity along the chemical freeze-out line.
