[FiveFeezy]

Well I just got a new 3.5 horse 60 gallon compressor and want to run air lines to cool the air and remove moisture. I've already done extensive research on the subject on this site and have decided to go with copper because I have a lot of it laying around.

My question is on the sizing of the pipe. I have 10 feet of 1 1/2" pipe, 10 feet of 1" pipe, 10 feet of 3/4" pipe, and 20 feet of 1/2" pipe, all in type L

I also have tons of type M in 3/4" and 1/2".

I want to use the type L because it is stronger and I have larger pipes which should help maintain pressure. But should I use the larger pipe closer to the compreesor or closer to the end of the line? The outlet on the compressor is only 1/2".

It seems that since the air is hot when it comes out of the compressor that I should run the small diameter pipe first because it can withstand higher pressure. On the other hand if I run the larger diameter first it seems like it may maintain pressure at the end of the line better.

Any thoughts are much appreciated.

[AntnyL]

Originally Posted by FiveFeezy

Well I just got a new 3.5 horse 60 gallon compressor and want to run air lines to cool the air and remove moisture. I've already done extensive research on the subject on this site and have decided to go with copper because I have a lot of it laying around.

My question is on the sizing of the pipe. I have 10 feet of 1 1/2" pipe, 10 feet of 1" pipe, 10 feet of 3/4" pipe, and 20 feet of 1/2" pipe, all in type L

I also have tons of type M in 3/4" and 1/2".

I want to use the type L because it is stronger and I have larger pipes which should help maintain pressure. But should I use the larger pipe closer to the compreesor or closer to the end of the line? The outlet on the compressor is only 1/2".

It seems that since the air is hot when it comes out of the compressor that I should run the small diameter pipe first because it can withstand higher pressure. On the other hand if I run the larger diameter first it seems like it may maintain pressure at the end of the line better.

Any thoughts are much appreciated.

A 3.5 hp compressor doesn't push much airflow (5 to 6 cfm?), so you're probably going to be running a tool that consumes 4 cfm max? Unless you're running more than 60-75 feet of pipe length, I'm thinking the 1/2" diameter pipe is fine all the way. The pressure loss will be minimal. If you have 3/4", you can go with that too, but it's overkill IMHO.

Antny

[FiveFeezy]

The compressor says it puts out 13.3 cfm at 90 psi.

[59 wagon man]

3/4" is fine and you can make the drops in 1/2"

[FiveFeezy]

I thought I read on here somewhere that larger diameter pipe cools the air faster.

[59 wagon man]

the size of the pipe won't make a big difference in cooling it

[AntnyL]

Originally Posted by FiveFeezy

The compressor says it puts out 13.3 cfm at 90 psi.

Even at 15 cfm and 100 psig pressure, the pressure loss through 1/2" diameter schedule 40 steel pipe is 1.0 psig for every 100 feet of pipe.

The pressure drop of 3/4" pipe at 100 psig and 15 cfm is under 0.25 psig for every 100 feet.

Either way, the pressure loss is negligible.

Here's a pressure loss calculator: http://www.engineeringtoolbox.com/pr...pes-d_852.html

Antny

[oldred]

Pressure loss would be negligible but the larger pipe will definitely cool better due to more surface area and the fact that a larger volume of air would move slower through the larger pipe. I would run the larger pipe as the primary and the smaller from the tee joints. But since you are lucky ( ) enough to already have the pipe on hand just run the large pipe all the way to your take off points. Also either type would be far more than adequate to carry the pressures you will be dealing with even if you later decide to go with a 175 PSI two stage compressor. Sounds like you have the material to build a top notch air line system and it most certainly will be worth the effort.

[FiveFeezy]

Thanks for the help guys. I've decided to use 1" and then 3/4" pipe. The 1 1/2" fittings are too expensive. I'll let you know how it works out.