A flushometer water closet on the top floor requires 20 psi residual. Static pressure is 65 psi, combined meter and backflow preventer loss is 10 psi, and the flush valve is 34 ft above the meter. How much pressure remains for friction loss in the piping and fittings?

Giải thích

Elevation loss is 34 x 0.433 = 14.72 psi, so 65 - 10 - 14.72 - 20 = 20.3 psi for friction. The 35.0 psi answer ignores the elevation loss, and 25.3 psi uses a 15 psi residual instead of the 20 psi a flushometer needs. The 14.7 psi choice is the elevation loss itself, not the friction allowance.