View Full Version : Is 3/8 air compressor hose with 1/4 fitting any different than 1/4 hose and fittings?


jimmybjj
12-08-2011, 09:31 PM
HF has 2 different hoses that i am looking at 3/8 and 1/4 but both 1/4 fittings. Will there be a performance difference? Thanks for any help.

MattT
12-08-2011, 09:51 PM
Yes there will be a huge difference. Resistance to flow is a function of both cross sectional area and length. The couple inches of 1/4" fitting at either end of a 3/8" hose don't reduce flow near as much as 50' of 1/4" hose.

Kevin54
12-09-2011, 08:10 AM
use the 3/8 hose but buy some hi-flow fittings

Mmfh
12-09-2011, 08:52 AM
If it were me I'd get my fittings somewhere besides Harbor Freight. I thought I would save some money and bought several male and female air fittings from HF.

They all leak! Leaking at the connection between the two pieces. Just not machined for a tight enough fit to be air tight.

I bought my fittings at the parts store, and buy steel not brass.

Just my 2 cents

Mm

scottydosnntkno
12-10-2011, 09:56 AM
one other thing is its similar to a compressor tank.

1/4" fittings will more or less flow the same amount whether they're on a 1/4" or 3/8" hose at the same pressure for the first few seconds. It then becomes a matter of volume, because the 3/8" hose holds twice the volume or whatever it works out to be than a 1/4" hose, so you will get max pressure for twice as long.

Similar to having a impact running off a 8 gallon or 80 gallon compressor. For the first few seconds both provide the necessary air volume, but the smaller reservoir loses pressure much faster due to the lesser volume, just as a 1/4" line vs a 3/8" line would.

If high volume isn't your concern, 1/4" is fine(nailers, small grinders, etc) but for heavy loads 3/8" is better, as even though you still have 1/4" ends, the hose itself will transfer pressure much faster.

MattT
12-10-2011, 01:05 PM
one other thing is its similar to a compressor tank.

1/4" fittings will more or less flow the same amount whether they're on a 1/4" or 3/8" hose at the same pressure for the first few seconds. It then becomes a matter of volume, because the 3/8" hose holds twice the volume or whatever it works out to be than a 1/4" hose, so you will get max pressure for twice as long.

The internal volume of 50' of 3/8" hose is 0.038 cubic feet. A 1/2" impact will pull damn near 1 cubic foot a second.

Provincial
12-10-2011, 04:05 PM
Believe it or not, there is friction between the inside of the hose and the air going through it. The more flow (volume) of air, the higher the effect of friction. This usually shows up as a loss of pressure. If you were to put a gauge at the compressor end of the hose and another gauge at the tool, there would be a drop in pressure at the tool each time you pull the trigger. The bigger the ID of the air hose, the less of a pressure drop. The longer the hose, the greater the pressure drop.

Almost all air tools with 1/4" NPT inlets will work fine with a 3/8" hose, even a very long hose. The quick disconnects on the ends will restrict the flow, and modern high-flow fittings will mostly eliminate this restriction.

bob15
12-10-2011, 06:10 PM
Skip HF.

Go to TP Tools and get their high flow kit:

http://www.tptools.com/p/172,47_Hi-Flow-Coupler-Kit.html


bob

Chris Adams
12-11-2011, 05:40 PM
If you can find somewhere else that HF, consider that on the hoses.
I have an HF 1/2 and a HF 3/8 both integrated into my system, between the two regulators and the piping.
Both hoses deteriorate at a very fast rate.
I mean, they have both been replaced due to cracking, then leaking in less than a year each time!
I've bought good hose from HF, but not their short pieces.

Cryptic1911
12-12-2011, 09:02 AM
stick with the 3/8" hose, and get high flow fittings like the ones linked from tp tools, or some milton v style fittings

ranger302
12-14-2011, 02:29 PM
Skip HF.

Go to TP Tools and get their high flow kit:

http://www.tptools.com/p/172,47_Hi-Flow-Coupler-Kit.html


bob

WOW that is $300 to retrofit my shop. Is it worth it?

bob15
12-14-2011, 04:33 PM
The hi-flows couplers will work with the "standard" I have (I forget the actual style name, though it isn't Lincoln for sure); So I bought couplers for the disconnects that would get used the most with the impact guns and die grinders. I have some couplings which will see a blow gun at best, those i didn't bother changing, mainly due to price as well.

The high-flow males were installed on my 3/8, 1/2 & 3/4" impacts guns and my 2 die grinders. The hi-flow really woke up the impacts, I haven't used the die grinder since installing them, just the "zing, zing" to see how it works).

Might try a couple/three kits and see how you like them. I personally will probably buy a couple more kits down the road. It's just not my priority yet.....

bob