Pipe for air compressor?? - Page 2

junquecol · 11-09-2008, 10:01 PM

Scott, I agree with most of your recomendations. As for line size, 1/2" will furnish over 100 cu ft, at 100 PSI. Most of us won't have a compressor capable of that much. Second, instead of PEX between comp. and pipe, use a hydraulic hose. Cuts down on transfer of viberations of comp. to piping.

scsmith42 · 11-09-2008, 10:13 PM

Bruce, that's good advice re the hydraulic hose - I actually have done that on my main compressor (27 CFM) and it works well. The PEX run that I was referring to below is a 200' buried run from one shop to another, so it shouldn't have any vibrations where it transitions from PEX to black pipe. I may install some type of accumulator tank in the new building though in order to help smooth out any pressure drops.

The problem that I have with the smaller pipe is that I see a flow loss when I'm using high CFM tools. I'm piping a longer distance though, so that makes a difference. Also, I often hang 50 - 100' of 1/2" air hose onto the end of the run, which has a cummulative effect overall.

1/2" would be find for shorter runs - maybe 75' total or less?

Alan in Little Washington · 11-09-2008, 10:27 PM

One other concern with PVC is temperature- its strength degrades as the temp goes up. Some newer compressors put out 175 psi which can put you in danger if it gets hot.

I used copper because it is easier to run and sweat than it is to cut and thread steel. Some threads will tell you to use the heavier walled copper, K grade (it comes in K, L, M grades), but the thinner, M grade, is fine - 3/4" is rated at 700 psi @ 100 deg F. Check it out in the Copper Tube Handbook, pp 24-25. Even if you happen to puncture it, since it doesn't shatter, there is no danger.

Sealeveler · 11-09-2008, 11:36 PM

Another vote for galvanized pipe.I have seen 1 1/4 pvc explode and seen the results.I am not sure of cfm but we had 2 - 10 hp compressors hooked together running at 175 psi.The slivers of pvc went through the plastic and insulation and put dents in the metal walls.Also damaged were some small parts for boats.Tony

Splinter · 11-10-2008, 09:52 PM

Thanks for all the replies and advice. I have ruled out PVC, PEX, black and galvanized pipe. So I guess that leaves copper and air hose. Copper 3/4" "M" pipe at Home Depot was $1.50 a foot today and air hose at HF was much cheaper. I like the look and neatness of using copper but it cost more and I don't have any experience soldering copper so I am still undecided but at least I have narrowed the choices.

Thanks again.

Splinter · 11-10-2008, 10:34 PM

Vol. 15 Issue 90 of Shop Notes has a nice article on how to install a copper piping in the work shop. It states not to use size "M" though.

TracyP · 11-10-2008, 10:37 PM

Soldering copper is actually an easy enough process to learn. Just be careful with the torch close to wood. DAMHIKT

FredP · 11-10-2008, 10:47 PM

Originally Posted by Splinter

Thanks for all the replies and advice. I have ruled out PVC, PEX, black and galvanized pipe. So I guess that leaves copper and air hose. Copper 3/4" "M" pipe at Home Depot was $1.50 a foot today and air hose at HF was much cheaper. I like the look and neatness of using copper but it cost more and I don't have any experience soldering copper so I am still undecided but at least I have narrowed the choices.

Thanks again.

If you go with hose I would suggest a thick quality hose for the main run. I had a good hose to begin with and got the fittings at HF. they sell a ??piece kit that has tee's and connectors to make up 4 drops. [I think!]

I had a dual tank portable compressor that the motor died on so I used the tanks to eliminate moisture in the lines. BTW hoses dont condensate like metal pipe does. maybe some but not nearly as much. I ran a hose from my big compressor tho the smaller tanks that I set up high. I put a moisture trap at the end of the line just before it conects to the bottom tank of the portable. then I brought the main line out of the top tank.to that I conected a splitter. On one both sides of the splitter I connected regulators. one is set to 100 PSI andthe other is set around 40 PSI for spraying. My compressor puts out 175 PSI and its too much for the air tools I have. if I need more I can ajust the reg. from there I ran a line through the cieling joists. when I got to a place for a drop I cut the hose and put a tee in. you can put in as many as you need wherever you want. adding new drops later is as easy as finding the ladder!

no soldering or threading of pipe needed. I used the spring type hoses for drops. I will probly do something different later because they stretch out with use and get in the way sometimes. setting up the compressor the way I did I get no moisture in the lines. the water trap has only been drained once in 3 years and only had about 2 drops in it. I drain the tank regularly. also you should shut off the compressor each day or when you wont be in the shop. hoses do break. mine did once.

DaveD · 11-11-2008, 03:57 PM

No, read some of the previous entries.

woodguy1975 · 11-11-2008, 05:09 PM

I used 3/4" SCH 80 PVC, but I would recommend this..

http://www.rapidairproducts.com/

You can buy the components from Mcmaster Carr as well. It is cheaper than PVC, pressure rated, and easier to install. I'm using it in my next shop for sure. I'll probably pipe it in the walls for a clean install.

Good luck,

John

Travis Porter · 11-11-2008, 05:09 PM

You don't need to run 3/4 for all of it. 3/4 is more than big enough for a trunk line and then 1/2 off of the trunk to your connectors. For me, all I have run is 1/2 inch pipe, no 3/4 and I really haven't had any issues. If you are doing an aircraft hanger like Scott, bigger is going to be better.

I will say I have the automatic hose reels and automatic electric cord reels in the ceiling and I love them. I strongly encourage you to use them if you can.

Splinter · 11-11-2008, 07:51 PM

Originally Posted by woodguy1975

I used 3/4" SCH 80 PVC, but I would recommend this..

http://www.rapidairproducts.com/

You can buy the components from Mcmaster Carr as well. It is cheaper than PVC, pressure rated, and easier to install. I'm using it in my next shop for sure. I'll probably pipe it in the walls for a clean install.

Good luck,

John

Ummm,,,Interesting product.

Has anyone here used this product?

Travis Porter · 11-11-2008, 08:16 PM

Very interesting. I have never seen it before, but it looks quite impressive.

JimmyC · 11-12-2008, 12:42 AM

Has anyone used Type M copper for air lines ? It's not recommended for air lines. I've got about 200' and was going to use it as secondary air (under 60 psi) to blow off machines.

TIA

Alan in Little Washington · 11-12-2008, 01:46 AM

Originally Posted by JimmyC

Has anyone used Type M copper for air lines ? It's not recommended for air lines. I've got about 200' and was going to use it as secondary air (under 60 psi) to blow off machines.

TIA

Who doesn't recommended grade M for compressed air lines?

Here is what the Copper Tube Handbook says:

"Compressed Air—Use copper tube of Types K, L or M determined by the rated internal working pressures as shown in Table 3. Brazed joints are recommended."

Since 3/4" grade M is rated at 700 psi and 1/2" almost as much, I don't see why not! And you don't have to braze it either. See my earlier post for the link.

All my 175 psi air lines are grade M copper.

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