A high rise building has a sink on the fourth floor located 2-feet above the floor. Each floor is 10-feet above the other. Calculate the psi at the sink where when the street pressure is 80 psi. The building does not have a pressure reducing device due to fire codes.

The pressure at a certain height is the pressure at sea level plus the hydrostatic pressure.

P = 80 psi + ΔP

where

ΔP = ρgh

ρ is the density of water equal to 62.4 lbm/ft³

ΔP = (62.4 lbm/ft³) (1 lbf/lbm) (4*10 + 2 ft) (1 ft/12 in) ² = 18.2 psi

Thus,

P = 80 + 18.2

P = 98.2 psi