VENTURI Pressure Drop

Use this tool to evaluate Venturi meter performance, estimate pressure losses, and compare operating conditions in piping systems.

Inputs Used
  • Velocity through orifice (Uo) (ft/s) – Fluid velocity at the Venturi throat
  • Velocity through pipe (Up) (ft/s) – Fluid velocity in the upstream pipe
  • Venturi Diameter (D) (ft) – Characteristic diameter of the Venturi
  • Coefficient (Co) (typically 0.98) – Discharge coefficient accounting for non-ideal effects
Outputs
  • Venturi Pressure Drop (Δh) is reported in feet of fluid.
  • Permanent Head Loss is also estimated and is typically 3–4% of Δh, representing irreversible energy losses due to turbulence.
How the Pressure Drop Is Calculated
  1. Evaluate velocity difference: The squared difference between the throat and pipe velocities represents the kinetic energy change across the Venturi.
  2. Apply Venturi relationship: The velocity difference is related to pressure head through the Venturi equation:
    (Uo2 − Up2)1/2 = Co · (2 g Δh)1/2
  3. Solve for pressure head (Δh): The result is expressed as feet of fluid.
Interpretation
  • Higher velocity through the throat (Uo) increases the pressure drop.
  • Larger velocity differences between pipe and throat result in higher Δh.
  • Venturi meters recover most of the pressure loss, making permanent losses relatively small compared to other flow measurement devices.
Uo
Up

Venturi pressure drop
(ft of fluid)
Δh = {{Venturi_pressure_drop__ft_of_fluid:Integer}}
Permanent head loss
(ft of fluid)
{{Permanent_Head_loss__ft_of_fluid:Integer}}