Fluid Properties & Flow Measurement

Worked: a venturi on a 6 in line

Water at 60°F (ν = 1.22 × 10⁻⁵ ft²/s) moves at 4 ft/s in a 6 in pipe: Re = 4 × 0.5/1.22 × 10⁻⁵ = 164,000, turbulent.

A venturi with a 3 in throat (A₂ = 0.0491 ft², area ratio 0.25) shows 4.0 ft of water head difference, C = 0.98. V₂ = √(2 × 32.2 × 4.0/(1 − 0.0625)) = 16.6 ft/s, so Q = 0.98 × 0.0491 × 16.6 = 0.80 cfs.