Size of Rapid Air System Needed?

[mark7980]

This my first post. I just purchased an Atlas Copco 2 stage compressor which has a CFM output of 15.9 @ 100 psi with a maximum pressure of 165 psi. I plan to have two outlets each about 15 feet from the compressor with drops to drain water before the outlets.

What size tubing do I need, 1/2" or 3/4"? I noticed the 3/4" tubing from Rapidair has an aluminum liner which might help cool the air and release moisture, as compared to the 1/2" which does not have the lining. Of course the 3/4" is double the price.

 

[slodat]

I have a mix of 3/4 MaxLine and 3/4 FastPipe. I highly recommend the MaxLine in your case. It’s a great setup and you won’t easily outgrow its capabilities.

 

[txvwnut]

According to rapid air 1/2” is good for up to 20cfm and the 3/4” is good to 35 or 40cfm, both these are for lengths up to 100 feet, anything longer and you would step up to the next size.

 

[Jbullfrog]

Bigger is better

 

[sberry]

At that distance 1/2 is fine.

 

[kythri]

The 3/4" MaxLine M7500 kit is a hell of a deal. If you're a Northern Tool Advantage member, it's $154.99 shipped:

http://www.northerntool.com/shop/tools/product_200484023_200484023

That said, check what you're shopping for. The 1/2" MaxLine kit is HDPE/Aluminum/HDPE, just like the 3/4" kit.

Amazon is showing the 90500 Master Kit:

https://www.amazon.com/dp/B0015A11U2/?tag=atomicindus08-20

1/2", 100ft, with two outlets for $75.31, but that is NOT a MaxLine kit, it's a RapidAir "Home Garage" kit, so it, specifically, is just nylon tubing, with a max PSI of 150, so you'd need to regulate flow into that.

The MaxLine M3800 1/2" 100ft kit:

https://www.amazon.com/dp/B00CZ7GTLU/?tag=atomicindus08-20

is roughly the same price as the M7500 3/4" 100ft kit:

https://www.amazon.com/dp/B005FKYRTU/?tag=atomicindus08-20

so there's really no reason to buy 1/2" over 3/4".

The MaxLine kits also come with three outlets, as opposed to two in the "home garage" kit.

 

[sberry]

This is so short might even 1/2 black pipe it. May be able to use all ready made fittings. Where I like the kits is long runs, way overhead.

 

[kythri]

I plan to have two outlets each about 15 feet from the compressor with drops to drain water before the outlets.

The MaxLine outlets have drains built into them.

 

[MattT]

Depends on what you're gonna use the air for. If you plan on using high demand tools, such as impacts, use the 3/4" tubing or 1/2" black iron.

 

[ToolRoom]

I have two smaller compressors linked together to give about 18cmf.

What I did was run a 3/4" main around the top of the shop, with 1/2" drops which feed out of the top, down to a T piece which continues on to a drain ball valve. Off the side of the T is a regulator with a water trap.

A ring main with drops is the ideal set up, but if you are unlikely to be working two outlets at once then radial circuits are fine.

I also have a home made cooler from copper pipe between the compressors and the main line. After battling water in lines for a long while, I'm happy to say with this new setup the water traps never see a drop.

3/4 may be overkill at the moment, but it means you will have very little flow loss, and plenty of room for expansion later if you need to add more length and drops. If you can afford it do it, I would say.