Wastewater Calculations

Formulas, Conversion, etc. from Spellman Book

Velocity, V

V = distance traveled (ft) / duration of test (min)

V=\frac{d}{t}

Flow in a Channel, Q

Q = width (ft) x depth (ft) x Velocity (ft/min)
Q=\frac{w\cdot d}{V}

Flow through full pipe, Q

Q = 0.785 x (Diameter-ft)² x Velocity (ft/s)

Q=0.785\cdot D\left(\operatorname{ft}\right)^2\cdot V

psi

pounds per square inch

1 day = _ min

1440 min

1 ft³ = _ gal

7.48 gal

Density of Water

62.4 pcf (lbs/ft³)

1 ft Water (Head) = _ psi

0.433 psi

1 psi = _ ft. Head

2.31 ft

theoretical atmospheric pressure (at sea level)

14.7 psi

Pressure of water at rest

P=\gamma h

density of water (pcf) x vertical distance (ft)

Gauge Pressure, P_G

P_{G}=P_{W}-P_{A}

water pressure - atmospheric pressure

Discharge (Flow), Q

Q = AV