Pipe size for 10000 LPM air flow

Questions & AnswersPipe size for 10000 LPM air flow
Cas Staff asked 3 years ago

Kindly specify the pipe size we can use for 10.000 LPM air supply.

3 Answers
Cas Staff answered 3 years ago

Hi Hitesh,

The correct size of the pipe depends on a number of things, it’s hard to give a definite answer.

First, one should aim for an as low as possible pressure drop in the system. To reach this goal, the pipes must be big enough. Unnecessary big pressure drop will result in (huge) increase of power consumption by the compressor.

General practice used to be to aim for a maximum pressure drop of 10%, or 0,7 bar in a typical installation. But nowadays, 0,1 seems to become more the norm (because of the energy savings).

The correct size of the pipe depends on two things:
– air flow
– length

Your 10.000 LPM air supply is the same as 600 m3/hr or 353 cfpm (cubic feet per minute).

Depending on the length of the pipe, the diameter of the pipe should be between 40 to 80 mm.
40 mm up to 50 meters.
80 mm up to 1500 meters.

Also, I assumed you where talking about 10.000 Nlpm (Normal liters per minute). ‘Normal’ means it is calculated back to normalized, atmospheric conditions (1024 mbar, 0 degrees Celsius). Most of the time, compressors specifications state this value (also called FAD = free air delivery).

In other words: it’s not the actual amount of compressed air that passes through the pipe. If it’s at 7 bar, 10.000 nlpm becomes 10.000/7 = 1428 lpm.

Hope this makes sense..

In other words, it the amount of air that is sucked in by the compressor.

The compressor would be around 60 kW for this kind of air flow, correct?

Anyway, search Google for “compressed air pipe sizing chart” and you’ll find many charts to help you calculate the best size (will include one on this site, with examples, soon).

Short question, long answer 🙂 Hope it helps…

Cas Staff answered 3 years ago

I can not understand about your statement as below:

If FAD condition, Air Flow capacity is 10.000
If at 7 bar, Air Flow capacity is 10.000/7 ?

My view is as follow, if we assumed the airflow capacity is 10.000 at 7 bar, its mean the Air flow capacity is 10.000 x 7 = 70.000 Nlpm

Cas Staff answered 3 years ago

Hi Hitesh,

What you say is correct. If capacity is 10.000 at 7 bar, it is 10.000 x 7 = 70.000 Nlpm

the liters per minute (lpm) is what you will measure when you install a flowmeter.

Calculated back to standard conditions (athmospheric, 1 bar, 20 degrees, dry air), that becomes 10.000 * 7 = 70.000 Nlpm.

(actually we have to account for the temperature differnce en water content, but that change is relatively small).


What you read in the manual of the compressor is 99% of the time FAD. Nlpm, not lpm.

Where did you get the 10.000 lpm from, from the compressor manual?

So if the manual says the compressor is 10.000 Nlpm FAD, than what you will actually measure using a flow meter will be 1428 lpm at 7 bar.

Manufacturers are not always clear when specifying the capacity. Sometimes they write lpm, when it should be Nlpm. It can be confusing.

To be sure, a compressor for 10.000 Nlpm (FAD) would be around 60 kW.

Hope this makes sense..