# Compressed Air - Pressure Loss in Pipe Lines - Online Calculator with Metric and Imperial Units

## Calculate pressure drop in compressed air pipe lines - metric and imperial units

The pressure drop in compressed air lines can be calculated with the empirical formula

dp = 7.57 q^{1.85}L 10^{4}/ (d^{5}p) (1)

where

dp= pressure drop (kg/cm^{2})

q= air volume flow at atmospheric conditions (FAD)(m^{3}/min)

L= length of pipe (m)

d= inside diameter of pipe (mm)

p= initial pressure - gauge (kg/cm^{2})

*1 kg/cm*^{2}= 98068 Pa = 0.98 bar = 0.97 atmosphere = 736 mm Hg = 10000 mm H_{2}O = 10 m H_{2}O = 2050 psf = 14.2 psi = 29 in Hg = 394 in H_{2}O = 32.8 ft H_{2}O

**Note!** - pressure is "force per unit area" and commonly used pressure units like *kg/cm*^{2} 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.

q-air volume flow at atmospheric conditions (FAD)(m^{3}/min)

L- pipe length (m)

p- initial gauge pressure (kg/cm^{2})

### Online Compressed Air Pipeline Pressure Drop Calculator - Imperial Units

The calculator below can used to calculate the pressure drop in compressed air pipelines.

q-air volume flow at atmospheric conditions (FAD)(cfm)

L- pipe length (feet)

d- inside diameter pipe (inches)

p- initial gauge pressure (psig)

**NOTE!** - a pressure drop above *1 kg/cm ^{2} (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/cm*^{2} (100 psig)

^{2}(100 psig)

Pressure drops in *100 m (330 ft) *compressed air schedule 40 steel pipe lines are indicated in the tables below: