1/4" Outlet with 3/8" Hose? What's the point?

by Ken Abel
(Plainfield, NJ)

I've had some trouble getting the flow out of my Craftsman compressor that i need.


I have two 1/4" 25' hoses with all kinds of quick connects in between.

After reading a bunch of stuff here online it seems to me i have to better organize the out put side on my system, perhaps upgrading to a larger ID hose. . . .BUT . . i have a basic question:

Does it matter if i connect with a 3/8" or 1/2" hose if the outlet of my compressor is just 1/4" ??? Doesn't that set the limitation right from the start?

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Aug 24, 2017
Bigger hose?
by: Doug in s.d.ca.

If you do the math, you'll see that a 3/8 hose is *twice* as big as 1/4.

So, those 1/4 in. hoses are a problem, definitely, unless you're running a pretty small tool.

But get bigger hoses first. There are also "high flow" (larger I.D. than industrial or Tru-Flate) couplers out there too. Since you'll be probably be needing some new ones, you might consider them.

You might also have a poor regulator, not passing the volume of air it should (or maybe not what *you need*).

What ARE you trying to run, anyway?

Aug 23, 2017
What's the point?
by: Bill

Good question with a fairly complex answer, Ken.

The pressure drop pages on this site will provide more detail.

Essentially though, if you've a long hose with a larger diameter than the outlet from the compressor, that's good.

A long hose with an equal diameter to the outlet will create more air turbulence, and greater pressure drop over the length of the hose.

When you say yours has "all kinds of quick connects in between", each fitting adds to the pressure drop of the air as it passes. A long enough hose with enough fittings would end up with virtually no flow at the outgoing end.

When you say "trouble getting the flow out of my Craftsman compressor that i need" to me that suggests that your compressor is undersized for the air demand.

You might consider looking at the compressor sizing pages on this site too, for some insight into this.

A 1/4" I.D. air line flows an enormous amount of air.

Odds are good that if your air tool isn't getting the air it needs, it's not the plumbing, but the capacity of the compressor that's the issue.

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