Per NFPA 13 – Table 188.8.131.52, the minimum required residual pressure at sprinkler pipe for Light Hazard Occupancy would be 15 psi (1 bar) and for Ordinary Hazard Occupancy would be 20 psi (1.4 bar).
For Extra Hazard Occupancy shall be based on the hydraulic calculation methods for certain building.
The piping, fittings and other system components shall be rated for the maximum system working pressure for the minimum 150 psi (10 bar) – NFPA section 10.1.5.
NFPA indicates the minimum required pressure for sprinkler system but the actual pressure in system depends on the street fire protection system’s water pressure. As long as the piping systems including fittings and other components meets the minimum working pressure 150 psi, and pipe sizes be designed per NFPA flow and minimum pipe size requirements the actual pressure would be the street pressure. The Back flow preventer (BFP) and isolation valves are required between the building and street connection (Per local jurisdiction).