Air Compressor Hose Size

[Bainbridge]

Installing our new air compressor next week, wondering what diameter hoses you are all running?

Keg washer wants about 14 CFM (Premier Two-Station Semi), mobile bottlers want more like 17 CFM. On our old compressor (3 hp/60 gal) we just ran a 100' length of 1/2" air hose across the shop. But that hose was expensive and cumbersome, and thanks to the compressor's leaky head gasket, it's now full of oil and condensate. New compressor is bigger and better (5 hp/80 gal), and being moved to a new spot where we can hard pipe a 1/2" air system to the wall, through the filters, etc. Plan is just to run a short length of flexible hose to the machines from the end of that, no more than 12 feet or so. Would 3/8" work for that last leg? Just easier and cheaper to find 3/8 than 1/2 out there.

Cheers!

[3guysandabeerd]

Russell why not try pex tubing we ran most of are on 3/4 pex then necked it down to the fitting we need at the end put a drop in to release water out the bottom you also want a compressor that doesn't work at high speeds creates heat and in return water in the line
hope this helps
cheers matt

[Houston_John]

3/8" hose is generally considered to be good up to about 20 cfm. That's accounting for pressure loss through the system (~100' of pipe/hose). If it were me, I'd hit the local harbor freight as my stores here in Texas have the Goodyear hoses. Or it looks like you can get Parker hoses (USA) on eBay for a good price also.

[Heisenbeer]

Wow, 100' of 1/2" hose will give a huge pressure drop for that distance. I was in the hydraulic/pneumatic industry in my 'other life' and can tell you that an improperly sized lines can negate any increase in compressor size and add to your frustration. After all, you only have 100 - 125 PSI to start with, you could be losing as much as 30 PSI at the end.
Try an online pressure drop calculator to size the piping correctly, such as this site http://www.engineeringtoolbox.com/pr...pes-d_852.html.

I would run black pipe or copper, after you make sure it is cleaned, (never ever run galvanized, it flakes off and gets in your system with use). Wherever you have a use point, T off the black pipe on the top of the pipe and make a double elbow to drop down. This helps prevent the oils and water from the compressor from getting into your washer and devices you are using. Just off the top of my head, I would be running 1" black pipe for a 100' run like that.

Also, just because something is rated for water pressure does not mean it can handle air pressure. I've seen companies use schedule 80 PVC pipe before only to have the joints blow apart on them. Plastic degrades over a period of time as well as the joints.

Lastly, make sure you have a good filter coming right out of your compressor, one that catches water, oil and junk. Dump the water valve at least weekly.

Cheers

[Bainbridge]

Yep, it's all about doing it right this time around, versus "Oh crap, we need an aircompressor, like, yesterday. Quick, go buy the biggest one Sears has!"

We'll most likely be running black pipe or copper at 1/2". And the new location will make a run of no more than 25'. Three filters in a row: oil/water, desiccant, odor adsorption, plus the unit has a built-in aftercooler that should drop a about 2/3 of the condensation out right in the tank, which is set with a pneumatic drain valve.

At 17 CFM and 125 psi, even with 3/8" it looks like we'd lose only 3 psi from the line, and then a couple more from the filters. A 1/2" run of that length is just a 0.75 psi drop. So say 25 feet of 1/2 for a drop of maybe two-three psi (have to check those filters, they've got 1/2 threads going in) then a 25' reel of 3/8 for another three psi, so only down 6ish for the system. Regulator on the keg washer wants 80-90, so I think it should be fine if the line can handle the CFM we need. It's kinda right on the edge. Might just go for 1/2.

[TGTimm]

Russel:

We use 1/2" copper for our main runs, with about 130' of line to the bottler--our longest run. Our drops to the bottler and keg washer are 1/2" PE tubing. To insure we have sufficient volume at the bottler and keg washer--which need big bursts of air when they need it--we have "surge tanks" made from old portable compressor tanks. This set-up works very well.

Use a secondary regulator after the main storage tank of the compressor, set to 80-100 psi. This will allow you to run the compressor at its maximum pressure, usually 150-175 psi for more air volume and less frequent runs. With the secondary regulator, you can keep the pressure down to safe levels for whatever you use for drops.

If I were setting up a new air system, I'd skip the copper/black iron and use Rapidair's PEX/Al/PEX tubing. It's rated at 175 psi air, is easy to run, and eliminates most tight turns, getting you a few more psi and cfm at your point of use. I rigged our new compressor with the 3/4" Maxline, and it was a breeze, not to mention the difference in cost compared to copper or black iron.

PS: I have about 70' of the Maxline left over. PM me if you'd be interested.

BTW--Folks, never use PVC piping for compressed gasses. When it fails, and it will, it breaks into nasty shrapnel that can maim or kill. Think "pipe bomb".