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- p
_{1}- inlet pressure - Absolute pressure at the Venturi inlet
- p
_{2}- throat pressure - Absolute pressure at the Venturi throat
- Δp - pressure drop
- Measured pressure difference
- D
_{1}- inlet diameter - Venturi internal inlet diameter
- D
_{2}- throat diameter - Venturi throat diameter
- e - expansion factor
- Coefficient used for compressible flow calculation
- C - coefficient of discharge
- Coefficient used for Venturi tube based on ISO 5167
- R
_{eD}- inlet Reynolds - Reynolds number calculated in front of the Venturi tube
- R
_{ed}- throat Reynolds - Reynolds number calculated at the Venturi tube throat
- q
_{1}- volumetric flow rate - Fluid flow rate in terms of units of volume per unit of time on the inlet conditions
- q
_{}- standard flow - Flow rate at standard conditions. Used only if the selected fluid is gas.
- ṁ - mass flow rate
- Fluid flow rate in terms of units of mass per unit of time
- V
_{1}- upstream velocity - Flow velocity at the Venturi tube inlet where flow diameter is D
_{1} - T
_{1}- upstream temperature - Fluid temperature for gas density calculation based on the ideal gas state equation
- ρ
_{1}- upstream density - Fluid density at the Venturi inlet in terms of mass per unit of volume
- R - gas constant
- Gas constant in terms of energy per unit of mass and temperature, for gas density calculation using ideal gas state equation
- κ - isentropic coefficient
- Specific heat ratio
- ν - kinematic viscosity
- Result of fluid particles colliding to each other and moving at different velocities in terms of area per square unit of time
- μ - dynamic viscosity
- Result of fluid particles colliding to each other and moving at different velocities in terms of mass per square unit of distance and time

- Select Venturi tube type based on its manufacturing technology
- Welded
- Venturi tube manufactured by welding
- Casted
- Venturi tube manufactured by casting
- Machined
- Venturi tube manufactured by machining

- Select value to input. You should enter selected one. The other one will be calculated
- p
_{2} - pressure in the throat of the Venturi tube
- Δp
- measured pressure difference in front and in the throat of the Venturi tube

- Select value to input. You should enter selected one. The other one will be calculated
- ν
- kinematic viscosity
- μ
- dynamic viscosity

- Select value to input. Available only if gas is selected. You should enter selected one. The other one will be calculated
- T
_{1} - upstream temperature.
- ρ
_{1} - upstream density.

- Select fluid type
- Gas
- for compressible flow where ideal gas state equation is applicable
- Liquid
- for incompressible flow of liquids

- Application of ISO 5167 constraints
- ISO constraints
- Deselect if you don't want to check if the Venturi tube and the flow conditions are within the limits of the ISO standard.