Pneumatic Air Tools - Hose / Compressor Friction Loss?

[WreckerOp911]

Good Evening-
My apologies if I have posted this question in the wrong forum, I read thru the forums and to be honest, I am not smart to know where it should go-

On the apparatus I operate,we carry rescue tools and one set is a pair of pneumatic breakers in which is powered by a compressor that is rated @ 375 CFM and set at 110psi.

I would like to know how if possible to find out what the friction loss would be in the 100' hose lengths we use?

Hose is rubber and comes in 2 1/2", 1 3/4", 1 1/2", 1", and 3/4" sizes each in 100' lengths.

What I am trying to figure out is how far I can go in feet to use the breakers without losing power from friction loss. Both breakers need 90psi -

Thank You

 

[jrmichler]

In order to answer, we need to know how much air each breaker uses. It should be in the owner's manual. If that's not available, do you have a make and model number? Are both breakers used at the same time?

Also, how far do you want to go? Compressed air can be conveyed as far as you want. It's just a matter of using right size hose.

 

[jack action]

https://www.engineeringtoolbox.com/pressure-drop-compressed-air-pipes-d_852.html :

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

dp = 7.57 q^1.85 L 10⁴/ (d⁵p)

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

https://www.engineeringtoolbox.com/air-hose-friction-d_1536.html :

Compressed air friction loss in hoses are indicated below. Gauge pressure

• 50 psi - black line
• 70 psi - red line
• 90 psi - yellow line
• 110 psi - blue line

https://www.about-air-compressors.com/estimating-pressure-drop/ :

Quick Guideline To Estimating Pressure Drop​

The following guidelines will help you guesstimate pressure drop without using complex formulas:

• If your air line is up to 3/4″ I.D., then assume a loss of up to 10% of your available air pressure for every 100′ of air line
• If your air line is between 1″ – 2″ I.D. then assume 5% loss per 100′ of air line
• For air line 2 1/4″ and up assume a 3% pressure drop per 100′ of air line and you should be safe

Making Estimating Pressure Drop For Fittings Simple​

To make it simple, and to err on the side of caution, if I were estimating pressure drop for the fittings in my supply airline, I would factor in 5′ (five feet) of an extra airline for every fitting, to allow for fitting caused pressure drop.

If I had 20 fittings from my compressor to my application, that would be the equivalent of an additional 100′ of airline added to the total airline length I would use to figure my pressure drop over that distance.

In the larger fitting sizes, the pressure drop caused by the air fitting is less, but for simplicity’s sake, I would still use the factor of 5 feet of airline length for every fitting in the air circuit.

 

[Lnewqban]

Air may be cooled down enough along its path through the hose as to induce precipitation of condensate (inside the hose) that would reach the pneumatic breakers.
If so, that driven-by-air water may affect the calculation, and should require a water separator at the end of the run.