E4.3 Venturi - Liquid Flow

Example 4.3: How much water is flowing through a pipe if a venturi meter reads 1 in of mercury. Water is at a temperature of 110 °F and nominal diameters for venturi meter are 4 in and 3 in, respectively. Use the following information:

C_V = 0.984 (for Re >10⁴); density of water = 61.86 lb/ft³

Density of mercury = 840.7 lb/ft³; kinematic viscosity = 6.67 ´ 10^-6 ft²/s

Solution

Pressure drop, ΔP (Equation 4.1):

Diameter of the upstream pipe, d₁ = 0.351 ft.

Diameter of the pipe at the throat, d₂ = 0.256 ft.

Diameter ratio, β (Equation 4.6):

K (Equation 4.5):

Velocity of the fluid, V (Equation 4.4) as 9.93 ft/s.

Reynolds number (Re):

Re is greater than 10⁴ hence C_V value is appropriate.