Compressor guru question

[coilcj]

Maybe a stupid question but physics is not my thing and I am sure someone has researched it already. Here is the deal, I share a shop with my old man, the compressor (60 gal dual stage) is in the front part of the shop and I am in the back. The run of pipe from the compressor to the area I am in is probably well over 100 linear feet of pipe. My first question is, am I going to get much drop off in CFM making that run (through 1/2"id pipe)? Second question, I have an old 25 gallon compressor with a blown pump that I was thinking about plumming into the back as a reserve tank (removing the pump and motor of course, just using the tank), would this solve a drop off issue I might have or just be a waste of time. Thanks for any insight!

[dopeassjackson]

1/2in pipe is way to small i get alot of drop in a 25ft piece but only with a 25gallon tank.
what are you useing for pipe? im useing just plain old steel pipe and im sure after 10+ yrs its all rusty inside. i would probaly use a plastic air brake line if i do it again, smoother turns and its easy to bend.

[mudevil]

I think 1 inch is whats recomended on a 100ft run.

[suprdave737]

Yeah, 1 inch line , and the extra tank capacity wont hurt anything, and should help catch any consensation. Put the inlet on the side, outlet on top, and have a drain you can get to.

[Kreep]

Technically, I don't think there will be any drop in CFM, but the air will be delivered at a lower pressure. For electrical stuff you worry about voltage drop, for compressed air you worry about pressure drop.

Pressure drop depends on three things, CFM, effective length of pipe and pipe diameter. There is a calculator and chart here (note the link to pipe ID)
http://www.engineeringtoolbox.com/pressure-drop-compressed-air-pipes-d_852.html

I put the following into the calculator:
15 CFM
100 foot run
0.62 inch diameter
150 psi initial pressure

Total pressure drop - 0.66 psi

I ran 1/2" copper in my shop, about a 90' run although I use taps at 50' the most. I was planning to put an old 10 gallon tank on the end, but pressure drop has never been an issue. I would add the old tank at your end of the shop, but mostly to reduce the frequency the compressor starts which will make your motor last longer.

Whatever you do, run steel or copper pipe - never use plastic. A pipefitter I know got called out to a shop to replace all the plastic line with steel after it blew and took a guy's leg off at the knee. Just not worth it to use plastic.

[coilcj]

Thanks for the info. My dad insisted 1/2" would be enough and I told him I didn't think it would not be. Thanks for that link as well, I will probably put that tank at the end of the run just to add extra capacity.

[krb]

Using copper pipe would be a good choice.

[coilcj]

Using copper pipe would be a good choice.

Old man river actually ran copper before I knew it, got that part right just the size was wrong. I would guess pipe would be stronger, but probably much more costly. I will probably just replace the copper with larger diameter copper.

[ChiScouter]

Don't replace anything, use your aux tank at the end of the run and you will be fine. 90 percent of guys are running at 50ft of 3/8 hose with fittings that restrict the hell out of the airflow and getting along fine. Im sure your 100ft of 1/2 inch pipe has less pressure drop than a 50ft of 3/8 hose with 1/4 inch couplings.

[Albin]

Old man river actually ran copper before I knew it, got that part right just the size was wrong. I would guess pipe would be stronger, but probably much more costly. I will probably just replace the copper with larger diameter copper.

If you're going to run copper pipe, don't replace what's there. Just add to it by making another circular circuit around the shop that meets at your end..