# Pipe flow calculators

## Air flow calculator

#### Calculator Description

Compressible air flow and pressure drop calculator can be used for air flow through round closed pipe. Pressure drop or flow rate can be calculated, as temperature is considered to be constant.

• Calculate:

• Pressure losses due to friction or local resistances
• Air flow rate
• Flow mean velocity
• Friction factor
• Reynolds number
• Input:

• Pressure on the start or on the end of pipeline
• Weight or volumetric flow rate at standard conditions
• Inside pipeline diameter
• Pipeline length
• Air temperature
• Local resistance coefficient K
• Pipe surface roughness

#### Calculator Features

• Applicable for laminar and turbulent flow
• Pressure difference due to change of height is not included in this version of calculator
• Temperature is considered to be constant

If you would like to use the calculator, but actually can't see the blue CALCULATOR button in the upper left part of the page than please read instructions.

Q: Calculate pressure drop created by air flow of 500 m3/h in pipe line with 60 mm internal pipe diameter and pipe length of 100 m. Air temperature is 273 K, pipe roughness 0.02 mm, local resistances coefficient is 0.

A: Calculation setup:
Calculate for: pressure drop
Input one from following two:
p1 - absolute pressure on the pipe start
q - volumetric flow rate at normal conditions
Enter values:
q = 500 m3/h
p1 = 6 bar
L = 100 m
D = 60 mm
T = 273 K
kr = 0.02 mm

Q: Calculate flow rate of air in pipe with internal diameter of 20 mm and length of 200 m. Created pressure drop is 2 bar. Internal pipe roughness is 0.02 mm and local resistances coefficient is 5.

A: Calculation setup Calculate for: flow rate
Input one from following two:
p1 - absolute pressure on the pipe start
Enter values:
p1 = 6 bar
p1 - p2 = 2 bar
L = 200 m
D = 20 mm
T = 273 K
kr = 0.02 mm<
K = 5

Q: Calculate pressure drop created by air flow rate of 20 m3/h at standard conditions in pipe with internal diameter of 5 mm, pipe length of 20 m pipe roughness of 0.02 mm and local resistance coefficient of 5.

A: Calculation setup:
Calculate for: pressure drop
Input one from following two:
p1 - absolute pressure on the pipe start
q - volume flow rate
Enter values:
q = 20 m3/h
p1 = 16 bar
L = 20 m
D = 5 mm
T = 273 K
kr = 0.02
K = 5

Compressible air flow calculation is based on the pressure drop equation for isothermal flow: