Question

31. A pressure difference of 500 Pa is available to force 20oC air through a circular sheet-metal duct 450 mm in diameter and 30 m long. At 20oC, p = 1.204 kg/m3 and take friction factor, f = 0.016. Determine the velocity.

Answer 1

$\Delta P=\frac{flV^2\rho}{2D}$

$500=\frac{0.016*30*V^2*1.204}{2*0.45}$

500 = 0.6421V²

V² = 778.69

V = 27.91m/s