Pvt diagram


I simulated free convection for water using the LBM (Ra=10000, only several degrees of Kelvin between the lowest and heights temperatures).
After getting results (density, velocity and temperature fields), I tried to compute the pressure for the water according to the known densities and temperatures and the pvt thermodynamic diagram for water. I got pressure values which are not reasonable (more than 10 atm !).

What did I miss? Can I take density and temperature (after transformed back to physical units) from the free convection computation and find pressure values from the pvt diagram?

Thanks alot