Tools, Sharpening and Power Machinery - air compressor plumbing

All,

I know some of you guys tinker a lot with these machines. Can you tell me what type and size pipe is best for pluming a few lines off a 60 gallon unit? Is copper an option? Do you need a short run of flex tubing close to the compressor to dampen out the vibrations? I heard the pipe needs to be pitched some for the condensate to drain back into the tank, but if I install a filter right off the receiver, would I still need that pitch? Any recommendations for a heavy duty air filter?

Thanks for any advice and info.

I am not sure what pressures you are using. If you go with copper, I would use type "L". It also makes a difference with what type solder you use. I have included a chart so you can see the differences.
I have always used Norgren filters and oilers. I would also put a drain valve on the end of the run so you can blow any water the filter misses out of the line. I also would use a flex connection to eliminate vibration. Besides the irritation of the vibration, it is hard on the piping. Good luck with your project.

http://www.copper.org/applications/plumbing/techref/cth/tables/cth_table4.htm

Very handy table. Since it rates MWP according to temperature, I have another question: what is the temp of "just compressed" air. I don't expect the pressure in the line to ever go above 135-140psi. But I do want to safety factor it to about 300.

I have felt air lines in shops that I have worked in and did not find really hot temps created by the air itself. I have seen heat exchangers used to dry the air and this does raise the temp but I don't see you having a problem. Always good to add a safety factor in you piping. Most have a 150% built into them. We always had to test piping systems at 1-1/2 times the working pressure.

Use type L copper and sweat liek a water line using 95/5 tin antimony solder. Just brace the lines and it will hold up fine.


For up to 15 cfm, use 1/2 line, for 20-30 use 3/4.

Also, use a hydraulic hose to connect the compressor to your hard lines, as the vibrations are what kills sweated joints.

Norgren is a big name in filters, but alot of people have problems with thier automatic filter drains. I have been very happy with my speedaire stuff form grainger.


Jim

In my shop I just used 1/2" PVC for plumbing the air lines across the shop. I know of several commercial shops and friends who also do the same. I have a 6.5hp-60gal compressor hooked to it for about 10 yrs or so - never any problems. I have a short piece of 5/8"{?} hose connecting the compressor to the PVC. I do have a regulator and filter at the 2 outlets, an open ended shut off valve at the lowest point of plumbing which releases all air and water after shutting the compr down at end of day. Of course the tank itself needs draining every so often.

Id replace that PVC ASAP. The reason is that certain chemicals found in compressor oils eat away at plastics, so one day, your PVC is gunna blow out on you.

Its fine for low PSI, but there is a reason you wont find too many OSHA shops using it.


PVC is NOT A GOOD MATERIAL for air lines, and I highly recommend taking it down. It has been known to shatter with devestating results.


Jim

marksr,

I will echo the comments about the use of PVC for compressed air lines.
It is forbidden to use pvc for air delivery unless there is an approved shielding surrounding the pipe.
As was said, it can deteriorate from being in contact with oil and can also suffer from stress cracks caused by pulsations from the compressor.

Safety info. (http://www.osha.gov/dts/hib/hib_data/hib19880520.html)

More pvc info. (http://www.woodcentral.com/bparticles/airpiping.shtml)

Yeah, I was in a shop where a polycarbonate filterbowl randomly burst, it was violent. Luckily nobody was hurt. The Oil just ate away at it, and it was a Norgren filter too!


Jim

Thanks for the info. Never had heard of any of it. Although I doubt I'll replace it anytime soon [$], it is defenitly something to think about.

I think there's a way you can shield the exposed runs of pvc to safeguard the area and people around it. That shouldn't be difficult or expensive. Good temporary fix.