Air hose

[Fredxx]

I'm struggling to find any data on pressure drop vs flow & pressure for

10mm^2 hose.

Any pointers? Google seems to have failed me!

[Andy Burns]

The Engineering Toolbox is good for that sort of thing

[Fredxx]

Thanks.

I found that, but doesn't go below 15mm internal diameter.

[newshound]

Flowrate will be down to around 40%. How accurately do you need to know?

[Roger Hayter]

Laminar flow is proportional to the fourth power of the radius. I think turbulent flow falls even faster in smaller pipes, but I am not sure. From above, flow in a 10mm tube is 20% of flow in a 15mm one.

[Andy Burns]

Could you extend the middle scale on the nomogram? looks like it halves per unit distance, does that make it ln(2)?

[Fredxx]

?? I'm looking for pressure drop over a length.

Given the few sizes of air hose, 6, 8 and 10mm^2 (I have come across

14mm^2) I am surprised there aren't simple tables around showing drop with air flow wrt to pressure and hose size.

[Fredxx]

I could but surprised there aren't simple tables around for such a common issue.

[Vir Campestris]

The page starts of with a formula including diameter.

It then has 2 calculators.

The metric one will give you answers for 1m^3/min, 1m length, 10mm pipe,

7kg/cm^2.

Perhaps you should try shorter pipes or higher pressures.

Andy

[Andy Burns]

Once fred mentioned it, I tried a few values and it seems quite determined not to like the inputs

[Tim Lamb]

I have about 50m of braided plastic 10mm? hose attached to my workshop compressor. (means I can reach a flat tyre anywhere in the yard) Clearly there are losses on full flow but it still serves to blow dust out of radiator fins....

[Fredxx]

I have now used it and the numbers seem low.

For instance, an impact wrench might take 8 CFM, (all measurements from the web seem to be in imperial) 1CFM = 30ltr/min so such a wrench would take 0.24m^3.

Over a 10mm hose over 10m @ 5bar that equates to a minimal pressure drop of 0.2 bar, which seems low to me.

I have rounded numbers for convenience.