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Nozzle and Venturi nozzle calculator

calculation of flow rate through nozzle

Nozzles and Venturi nozzles are devices that are inserted in circular cross-section conduit to create pressure difference of static pressure. Based on that pressure difference, flow rate of flowing fluid can be calculated.

Three types of nozzles are covered in calculator: ISA 1932 nozzle, long radius nozzle and Venturi nozzle. All three types differ from each other based on its shape. All nozzles have radius shaped convergent inlet with cylindrical throat and Venturi nozzle also has divergent part as outlet.

Nozzle and Venturi nozzle calculator can be used for both liquids and gases. Calculator is applicable for subsonic flow and single phase fluid. Gas is considered as compressible and ideal. For gas flow, pressure ratio p2/p1 must be equal or greater than 0.75. Calculator is not for pulsating flow.

Calculation of gas flow with higher pressure drop and flow close or equal to choked flow conditions gas discharge calculator should be used.

Limits of use for nozzles are:

  • 50 mm < D < 500 mm
  • 0.3 < β < 0.8
  • 7x104 < ReD < 107 for 0.3 < β < 0.44
  • 2x104 < ReD < 107 for 0.44 < β < 0.80

Limits of use for long radius nozzles are:

  • 50 mm < D < 630 mm
  • 0.2 < β < 0.8
  • 104 < ReD < 107

Limits of use for Venturi nozzles are:

  • 65 mm < D < 500 mm
  • 0.316 < β < 0.775
  • 1.5x105 < ReD < 2x106

Flow rate through nozzles in calculator is calculated using:

rate through nozzles and orifices

where is:

  • q - flow rate
  • C - flow coefficient
  • A - cross section area
  • Δ p - pressure drop
  • ρ - density
  • gn - acceleration of gravity
  • hL - head loss

The values of hL and Δ p are measured differential static head or pressure before and after the nozzle. Values for coefficient of discharge or flow coefficient (C or Cd) can be calculated based on applicable standards like ISO 5167 or similar ASME standards.

Related calculators for flow rate measurement with pressure differential devices:
Orifice plate calculator
Venturi tube calculator
Prandtl probe calculator