Compressed Air - Pipe Line Pressure Loss - Online Calculator with Metric and Imperial Units
The pressure drop in compressed air lines can be calculated with the empirical formula
dp = 7.57 q1.85 L 104 / (d5 p) (1)
where
dp = pressure drop (kg/cm2)
q = air volume flow at atmospheric conditions (FAD) (m3/min)
L = length of pipe (m)
d = inside diameter of pipe (mm)
p = initial pressure - gauge (kg/cm2)
- 1 kg/cm2 = 98068 Pa = 0.98 bar = 0.97 atmosphere = 736 mm Hg = 10000 mm H2O = 10 m H2O = 2050 psf = 14.2 psi = 29 in Hg = 394 in H2O = 32.8 ft H2O
Note! - pressure is "force per unit area" and commonly used pressure units like kg/cm2 and similar are in principle not correct since kg is a mass unit. A mass must be multiplied with gravity g to be a force (weight).
Compressed Air - Pressure Drop Nomogram
The nomogram below can be used to estimate pressure drops in compressed air pipe lines with pressure 7 bar (100 psig).
- Download and print compressed air pressure drop nomogram!
Online Compressed Air Pipeline Pressure Drop Calculator - Metric Units
The calculator below can used to calculate the pressure drop in compressed air pipelines.
Online Compressed Air Pipeline Pressure Drop Calculator - Imperial Units
The calculator below can used to calculate the pressure drop in compressed air pipelines.
NOTE! - a pressure drop above 1 kg/cm2 (14-15 psi) is in general not relevant and the formula and calculators above may not be valid.
For a more accurate calculation - or for a longer pipe lines with larger pressure drops - divide the line in parts and calculate the pressure drop and final pressure for each part. Use final pressures as initial pressures for the next parts. The final pressure after the last part is the final pressure at the end of the pipe line. The pressure drop for the whole pipe line can also be calculated by summarizing the pressure drops for each part.
Compressed Air Pipeline Pressure Drop Spreadsheet
Calculations can be done for other pressures and/or pipe lengths by using this excel spreadsheet (metric units).
The same spreadsheet including different types of pipes (imperial units).
Or, alternatively - Compressed air pipe lines - pressure drop calculations - in Google Docs. You can open, save and modify your own copy of the Google spreadsheet if you are signed into your Google Account.
Compressed Air Pipeline Pressure Drop Table - Initial gauge Pressure 7 kg/cm2 (100 psig)
Pressure drops in 100 m (330 ft) compressed air schedule 40 steel pipe lines are indicated in the tables below:
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Properties of air, LNG, LPG and other common gases. Pipeline capacities and sizing of relief valves.
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