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- p
_{1}- pressure on the inlet - Absolute pressure in front of the orifice
- p
_{2}- pressure on the outlet - Absolute pressure after the orifice
- Δp - pressure drop
- Pressure difference between pipe start and pipe end
- Δω - pressure loss
- That can't be recovered after the orifice
- D
_{1}- diameter of tube - Internal pipe diameter
- D
_{2}- orifice size - Diameter of orifice
- e - expansion factor
- Coefficient used for compressible flow calculation
- C - coefficient of discharge
- Coefficient used for orifice plate based on ISO 5167
- R
_{eD}- upstream Reynolds number - Reynolds number calculated in front of the orifice
- K - resistance coefficient
- That you can use in pipeline calculation, as orifice is creating local pressure losses in the pipeline
- 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 in front of the orifice 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 in the front of orifice 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 orifice type based on the measuring taps placement
- Corner taps
- When measuring taps are placed in the orifice corners
- Flange taps
- When measuring taps are placed in the orifice flanges
- D - D/2
- When measuring taps are placed in front and after the orifice on given distance

- Select value to input. You should enter selected one. The other one will be calculated
- p
_{2} - pressure downstream from the orifice
- Δp
- measured pressure difference in front and after the orifice

- 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 orifice and the flow conditions are within the limits of the ISO standard.