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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.

OrificeAirD, d, p_{1}, p_{2}, TQ

Task: Calculate flow rate of air through the orifice plate. Orifice internal diameter is 100mm, and tube where orifice is inserted, internal diameter is 200mm. Pressure in front of the orifice is 104000 Pa, and pressure after the orifice is 100000 Pa absolute. Pressures are measured on the corner taps. Temperature of air is 15 C.

Solution:
Flow rate is: 1374.5 m^{3}/h

OrificeWaterD, d, p_{1}, p_{2}, TQ

Task:
Calculate flow rate of water flowing through orifice plate with external diameter of
120 mm and internal diameter of 80 mm. Measured pressures in front and after the orifice
is 11000 mm H_{2}O and 10000 mm H_{2}O. Pressure is measured on 1 inch taps.

Solution: Flow rate is: 54.674 m3/h

OrificeWaterD, d, p_{1}, p_{2}, TQ

Task: Calculate flow rate of water through the orifice with external diameter of 200 mm, internal diameter of 160 mm. Measured pressure drop in front of the orifice is 10729 mm H2O and measured pressure drop is 400 mm H2O. Pressures are measured at corner taps

Solution: Flow rate is: 155.94 m3/h