Air Compressor Line size

[Hawkins]

Hi all, I figured this would be best forum for this.

I have a 4 car carriage style garage. I have a single air compressor which I'd like to run air lines to various points throughout the garage bays. No single run will be more than 100-150 ft and I am not a heavy duty user -- potentially uses would likely be car maintenance and "wood shop" uses. The reason for the "longer" run is I have a 50 ft reel which will be hooked up. I am going to focus on reducing the run size but not sure how that'll play out.

I was looking at the Rapid Air MaxLine and was debating whether I should get the 1/2 inch or 3/4 inch line. I am thinking about pressure drop and trying to reduce drop over longer runs. Any thoughts or suggestions? I have no specialized tools and would likely just want something good enough to run an impact wrench, etc.

Thanks!

 

[matt_i]

I didn't do rapid air but used copper.

But, then its easy to do a "trunk line" of larger diameter and legs of smaller diameter.

If you are going to do 150' of pipe (measured in the single longest pathway from air compressor to the outlet) I would personally choose the 3/4".

 

[rsanter]

In general bigger is better

 

[cvairwerks]

This should help you get some idea on pressure drop vs flow rates for various pipe sizes. One thing to remember, is that these are steady state calculations, and the pipe lengths are assumed to be straight runs. Elbows and reducers will effectively change the length for the calculations. For your purposes, you can assume they have no change, with keeping your runs under the chart length.

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

 

[coljar]

3/4" for the long runs and 1/2" for the drops.

 

[eacmen]

FYi Last time i checked the 1/2” rapidair is actaully 3/8” ID, and 3/4” rapidair is actually 1/2” ID.

 

[nadogail]

IMHO, Copper is probably the most used choice, and I have found it easier to work with than Iron Pipe.
What do you have in your pile of "Neat Stuff" ? Iron pipe can be used in sections.

All the air in my little 2 car garage shop is distributed by rubber hose.

 

[Sweetcorn]

FYi Last time i checked the 1/2” rapidair is actaully 3/8” ID, and 3/4” rapidair is actually 1/2” ID.

I cant speak to the 1/2", but I just walked over and measured the ID of a leftover piece of 3/4" with calipers and it was right around .780".

 

[Ron_J]

I installed 1/2" rapidair and have no complaints. I can run everything i have including the airsanders and cutoffs without issues.

 

[allinon72]

Realistically you'd be fine with 1/2" from the use you describe, but there's no reason not to do 3/4"

 

[eacmen]

I cant speak to the 1/2", but I just walked over and measured the ID of a leftover piece of 3/4" with calipers and it was right around .780".

Good to know.

This is the kit I was referencing:

https://www.rapidairproducts.com/shop/rapidair/1-2-rapidair-nylon-tubing-100

Marketed as 1/2” but its OD, when air hoses are typically marketed as ID.

Good comparison for it here:

https://www.rapidairproducts.com/comparison-chart

 

[Sweetcorn]

Good to know.

This is the kit I was referencing:

https://www.rapidairproducts.com/shop/rapidair/1-2-rapidair-nylon-tubing-100

Marketed as 1/2” but its OD, when air hoses are typically marketed as ID.

Good comparison for it here:

https://www.rapidairproducts.com/comparison-chart

Gotcha, I used maxline so that's what I had to measure.

 

[Hawkins]

Thanks for all the help. I'll probably just go with 3/4 diameter. If i need more for drops, I'll buy more pipe in the 1/2 diameter. I know i planned on setting up a Filter/Lub. on the line. The 1/2 would save me some $ here but buy once cry once on the 3/4. Not too big of a difference. Thanks all!

 

[eacmen]

Thanks for all the help. I'll probably just go with 3/4 diameter. If i need more for drops, I'll buy more pipe in the 1/2 diameter. I know i planned on setting up a Filter/Lub. on the line. The 1/2 would save me some $ here but buy once cry once on the 3/4. Not too big of a difference. Thanks all!

30gal 120v Husky here.

I just installed their low end kit in the home garage. 3/8 ID. Plenty big for my use (mostly just used for cleaning off parts, tires, moving brake pistons and the occasional impact when the 20V fails).

I originally planned in putting a dryer/oiler right after the air compressor outlet. But instead just put the dryer then installed the oiler on one of the drops for the rare case I run a tool that needs oil.

 

[infinkc]

I used the 3/4 kit, figured it had more volume at the drops. No complaints about the rapidair besides the price.

 

[Shakes_26]

I'm putting in the '1/2 in." kit now, 2 car garage, it will give me a drop at the workbench, and each side of the garage door. One side, closest to the compressor will have the hose reel (~40ft iirc). So that might be the longest run.

I believe with the kit the paperwork showed a graph with distance-flowrate. In any case its enough for any of the tools, tire filling I care to run. We wont be painting so I'm not worried about volume.

 

[TTMotorsports]

I hate to say it but I used PEX in my old shop. In the 2 years of using the shop never a single issue or leak. I ran 150 psi through the lines in phoenix which is hot and never an issue. I had a long run to my plasma cutter and I went 1" main line with 3/4" drops and had no pressure drop over the run that i could measure.

Thanks

 

[Metal-Marc]

I have a 5hp 60gal compressor. I use 3/4" copper for the run and 1/2" for the drop. A friend gave me a dead pancake compressor. I tossed the compressor and kept the tank which I used just before the end of my drop after the regulator. It helps for keeping the pressure drop to a minimum.

 

[ericm]

My garage had 3/4" PVC air lines run by the previous owner. I used it for years until they needed to be removed during a renovation. I replaced them with 1/2 rapidair, the stuff that's 3/8" ID. Same compressor and tools. The performance of my air impact is noticeably poorer. When my shop is built I'll use 3/4 copper for the main runs, 1/2 for the drops.

 

[roc_on_the_rocks]

In general bigger is better

That's what she said!

 

[bigcreek]

I ran 1/2" iron pipe throughout my shop simply because I had a ton of it. If I had none on hand I would have gone 3/4. I haven't ever lacked for air though. That's with a Hypertherm 85 running on the CNC table 70 feet from compressor then a air impact running downline from that and never been shorted for air. But like has been said bigger is better.

 

[boostin1004]

I ran 1/2 copper line in my garage for a total span of 70 ft. I used copper lines to cool the compressed air and had four drops. Never had a problem not having enough air even when I was using my paint gun.

 

[bczygan]

According to this website:
https://www.engineeringtoolbox.com/pressure-drop-compressed-air-pipes-d_852.html

And based on the following:
17CFM compressor (Typical 5HP 2 stage at 175PSI and 200' of line.

1/2" ID pipe loses 4PSI (That's not very much!)
3/4" ID pipe loses .55PSI (That's insignificant!)

The thing to watch is the ID of the fittings.
https://www.vmacair.com/blog/hose-size-affect-compressor-airflow/

Bill

 

[justanengineer]

Use dictates needs obviously but many here do severely oversize air lines. Most commercial automotive shops run 1/2” and smaller impacts on 3/8 lines. My pot blaster runs fine on 50’ of 1/2”. I don’t recall what my 3/4” impact has for fittings but the 1” runs fine off a 3/4 hose. YMMV.


Sent from my iPhone using Tapatalk

 

[jhracer]

I just finished plumbing my shop and I used Pex-AL-Pex. 3/4" for all the runs. The hardest part was straighten the coil before the install.