P2904.6.2.1 Available Pressure Equation
The pressure available to offset friction loss in the interior piping system (Pt) shall be determined in accordance with the Equation 29-1.
Pt = Psup — PLsvc — PLm — PLd — PLe — Psp (Equation 29-1)
Psup = Pressure available from the water supply source.
PLsvc = Pressure loss in the water-service pipe.
PLm = Pressure loss in the water meter.
PLd = Pressure loss from devices other than the water meter.
PLe = Pressure loss associated with changes in elevation.
Psp = Maximum pressure required by a sprinkler.