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- p
_{1}- inlet pressure - Absolute pressure at the pipe start
- p
_{2}- outlet pressure - Absolute pressure at the pipe end
- Δp - pressure drop
- Pressure difference between pipe start and pipe end
- q - volume flow rate
- Fluid flow rate in terms of units of volume per unit of time
- ṁ - mass flow rate
- Fluid flow rate in terms of units of mass per unit of time
- L - pipe length
- Length of a pipe in which pressure drop is calculated
- D - pipe diameter
- Internal circular pipe diameter
- H - channel height
- The height of channel for rectangle shaped pipe
- W - channel width
- The width of channel for rectangle shape pipe
- k
_{r}- pipe roughness - Pipe internal surface roughness
- V - velocity
- Flow velocity in terms of units of distance per unit of time
- A - area
- Internal pipe cross section area
- f - friction coefficient
- Coefficient of friction for pressure drop due to friction calculation
- Re - Reynolds number
- Dimensionless number representing viscous versus inertial forces ratio
- δ - boundary layer
- Thickness of laminar layer formed in turbulent flow connected to pipe wall surface
- ρ - fluid density
- Mass per unit of volume
- 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
- K - resistance
- Coefficient used for calculation of minor losses due to local resistances in pipe line like bends, tees, reducers, valves, etc.

- Select value to calculate. You should enter not selected one.
- Δp
- pressure drop
- q / ṁ
- volume/mass flow rate
- D
- internal pipe diameter

- Select value to input. You should enter selected one. The other one will be calculated
- p
_{1} - pressure on the pipe start
- p
_{2} - pressure on the pipe end

- Select value to input. You should enter selected one. The other one will be calculated
- q
- volumetric flow rate
- ṁ
- mass flow rate

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

- Select pipe shape
- round pipe
- full cross section fluid flow
- rectangle pipe
- for rectangle channels and full cross section flow

PreDropWaterQ, D, L, kr, Δp

Task:
Calculate pressure drop in round pipe with flow of 5 m^{3}/h,
pipe length 100 m, internal pipe diameter of 25 mm and pipe roughness of 0.1 mm.
Flowing fluid is water with density of 1000 kg/m^{3}.
Local resistance can be negligible K = 0.

Solution: Pressure drop is: 4.78 bar

PreDropWaterΔp, D, L, krQ

Task: Calculate flow rate of water through closed round pipe with internal diameter of 25 mm, pipe length of 100 m. Pipe line connecting reservoir on the elevation of 20 m above the pipe exit with water flowing to open atmosphere. Reservoir is under atmospheric pressure. Pipe roughness is 0.1 mm.

Solution: Flow rate is: 3.16 m3/h

PreDropAirQ, H, W, L, krΔp

Task:
Calculate pressure drop of 2000 m^{3}/h of air flowing through closed
rectangle chanel to open atmosphere. Chanel width is 400 mm and height is 250 mm.
Chanel is with surface roughness of 0.01 mm. Local resistance coefficient is line is 3.5.
Chanel length is 85 m.

Solution: Pressure drop is: 298.96 Pa