Enlarging 1/4" port on air compressor

[seagull369]

I picked up an older CH air compressor at a flea market some time ago and just got around to futsing with it. It's a decent rig (not too much rot in the tank, made in usa 20 gallon dual piston oiled pump), but the outlet port is only a measly 1/4" NPT. All the junk connected from there is also all 1/4".

Anyway, I was toiling with the idea of enlarging the port on the tank to 3/8" but wasn't sure if it'd be worth the hassle given the flow gains I might achieve. The distance all the 1/4" piping travels is only, maybe, 8 inches or so before connecting to the hose- which is 25ft 1/2" with 3/8" automotive "T" type connectors. BTW, The oulet port is centered on a very large 2+ inch clean-out port, so enlarging it wouldn't compromise safety, or anything.

I'd be using the compressor for higher-demand stuff like die grinding, impact wrenching, air blowing. I have all the parts and tools to make it happen, but just wondering if it's worth the effort.

ANy thoughts?

 

[Schurkey]

It's a drilled hole, and a pipe tap away from trying. Yeah, it's worth the time. Screw the 3/8 hose directly to the outlet, bypass the regulator.

OTOH, 20 gallon tank will get you about three seconds of die grinding before you've lost enough pressure to kick in the compressor. You're going to hate that.

 

[dkmc]

How many CFM output is your compressor rated for?
At 90PSI a 1/8" hole will flow 23 CFM.
Sounds like your compressor is smaller than that.

 

[sberry]

The only tool this helps is the impact. The unit is so small that running out of air is what will be an issue for grinding, bigger pipe will just make it happen faster. 1/4 pipe cleaned and reamed is closer to 3/8 than 1/4 and a few inches isn't much. Add a t ahead of the reg or as was suggested screw hose ahead of it and eliminate some fittings.

 

[hangfirew8]

It's a decent rig (not too much rot in the tank, made in usa 20 gallon dual piston oiled pump), but the outlet port is only a measly 1/4" NPT. All the junk connected from there is also all 1/4".

3/8" air hose uses 1/4" NPT fittings. When you say "all the junk" downstream I'm not sure if it's 3/8" with 1/4" fittings, or the smaller 1/4" air hose. If it's air hose, by all means, replace it.

I used to run a 10 Gallon/120V system for everything (but I didn't sandblast, grind or sand/buff with it). When I got my first big impact gun, it wouldn't remove pickup truck lug nuts (about 110-120 lb/ft) at all, and car lug nuts were iffy. I put a pressure gage on a T and fittings, and did a series of inline pressure tests and found the biggest problems were the disconnects. The worst was a Harbor Freight disconnect at the end of my Goodyear hose. The second worse was the disconnect on the tank that everything ran off of.

I replaced everything with High Flow fittings (GuardAir, but Milton V is good), and suddenly I could remove the pickup truck lug nuts on the IR impact's setting 1 out of 5. So that's the upgrade I would recommend. You'll still have a longer recovery time, but your impact will hit as hard as the big boys.

 

[sberry]

And,,, the more one puts in the worse they are. The 1/4 barbs don't hurt much on a 3/8 hose. I like the hoses screwed direct if I can help it and use only 1 disconnect right at the tool.

 

[bob15]

I wouldn't waste my time. I would leave the 1/4 NPT and get some Parker HF series fittings.

https://www.parker.com/literature/Quick%20Coupling/catalog_sections/HF%20Series-Catalog%203800_SectionA.pdf

 

[radio2000]

I wouldn't waste my time. I would leave the 1/4 NPT and get some Parker HF series fittings.

https://www.parker.com/literature/Q..._sections/HF Series-Catalog 3800_SectionA.pdf

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[bob15]

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Here is a sales sheet. I get them when zoro has a 20/25% off sale. And they are USA made.

http://www.hoseandfittingsetc.com/product/fittings/quick-couplings/pneumatic-qc/general-purpose-pneumatic-qc/parker-hf-series-couplings

 

[seagull369]

I know 20 gallon is small, but its huge for me after screwing around with the oilless pancake for a couple of years now. I don't expect miracles out of it.

By the 'junk' connected downstream, I meant the manifold, air pressure switch, regulator and air coupler. It's all 1/4".

The pump SCFM is 8.2 @ 40psi, 6.5 @ 90. If it's worth anything, horsepower is rated at doubtful 4.5 on 125Vac. Pressure switch cuts power at 125psi.

To clarify, Hangfire, the hose I'm using is 1/2" with 3/8" NPT female threads on either end. To that I have a 3/8" air coupler screwed in on one and 3/8" plug on the other. Both of those are the automotive-style like this:

They're Craftman brand, which seem to be of pretty decent quality

 

[hangfirew8]

Since you top off at 120PSI, running air pressure at the end of the hose is lucky to be as much as 90PSI (running, not static). So you only need a regulator if you are painting with an airbrush or using some other pressure sensitive tool. I would either leave the regulator on a parallel path, or hook up disconnects on it, so you can switch it in and out as needed. You can make a very short air line for that with something called "hose barbs," and an old hose to cut up.

Eliminating the regulator for impact and other high flow uses will probably net you more than any other mod.

 

[thatguysb]

Im in the similar boat, i bypassed all the stock regs on my compressor and connected directly into the tank, i have a 50ft run of 1/4 airhose and thats my limiting factor, ill soon swap down to 20 ft of 1/2"

 

[Matt Matt]

Home Depot has a fairly inexpensive high flow quick connect.

I would probably start there and see if it suits your needs.

 

[Infinia]

The distance all the 1/4" piping travels is only, maybe, 8 inches or so.....Anyway, I was toiling with the idea of enlarging the port on the tank to 3/8" but wasn't sure if it'd be worth the hassle given the flow gains I might achieve. .

ANy thoughts?

Air line restrictions for short lengths manifest itself as losses in pressure at the tool only under high demands, hose diameter and more importantly hose length are the major contributors NOT these short lengths of hard line on your tank .
Since you already have 1/2 hose yer just gonna be gilding the lily for not much return. Your pressure switch may have an adjustment which will easily override tiny pressure losses due to fittings within reason. I'd only make adjustments or mods when you see real losses measured or felt at the tool, ideally with a pressure gauge at the tool input to verify gains made if any. The best special high flow fittings will gain a net 2.5-5 max psi over any of the cheapest versions you can find. The biggest problem is youll be relying on the pumps running CFM (low) when your high demand empties the tank in a couple of minutes thus any lossy tank fittings or restrictions will have much less ( negligible ) pressure drop than before. Perhaps a quick test at the tanks drain opening will show what can or cant be gained vs simply adjusting the pressure switch 10-15 psi upwards.

1. Avoiding those lame 125 psi compressors in the 1st place esp. for impact gun use. When you have a low cut-in pressure ~ 100 psi you only have 10 psi losses to work with! Also compressors that are >150 psi allows fixed small tanks act/ look bigger than a 125 psi one. Adjust compressors cut-in setting on the pressure switch by 10-15 psi. Check the tanks listed max WP and double check the safety valve is operational 1st. Homeowner grade pumps need to observe duty cycle limits since they'll now be operating for longer stretches.
2. Reduce air hose length or increase diameter.
3. Consider eliminating excess quick connects E.g. use only 1 at the tool. and/or bypass low flow regulators.
4. Lastly change to high flow fitting ( strangely this is the 1st thing folks tend do to do)