Free Venturi Meter Calculator

Determine the flow rate through a Venturi meter from upstream and throat dimensions and pressure difference.

mm
mm
kPa
kg/m^3

Volumetric Flow Rate

10.89 L/s

Beta Ratio (D2/D1)0.500

Volumetric Flow Rate vs Discharge Coefficient (Cd)

Venturi Meter Flow Measurement

A Venturi meter uses a converging-diverging section to measure flow with minimal permanent pressure loss.

Formula

Q = Cd A2 sqrt(2 delta_P / (rho (1 - beta^4)))

where A2 is the throat area, beta = D2/D1 is the diameter ratio, and the (1 - beta^4) term accounts for the velocity change between upstream and throat. Cd for Venturi meters is typically 0.95-0.99.

Example Calculation

A Venturi with 100 mm upstream and 50 mm throat, 15 kPa differential, water.

  1. 01beta = 50/100 = 0.5, beta^4 = 0.0625
  2. 02A2 = pi x 0.05^2 / 4 = 0.001963 m^2
  3. 03sqrt(2 x 15000 / (1000 x (1 - 0.0625))) = sqrt(30000/937.5) = sqrt(32) = 5.657 m/s
  4. 04Q = 0.98 x 0.001963 x 5.657 = 0.01088 m^3/s = 10.88 L/s

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