Compressed air piping question

Re: Compressed air piping question

Bill Grumbine, Kutztown PA

>Hi Harvey

I do not know how closely you may have looked at the system I put in when you were here for the picnic, but the drops are mainly to get the connector to where you can reach it. I installed a loop or whatever you want to call it on the recommendation of Jeff Jewitt to help keep water from draining down at each terminus, just as you suspected. Mine are only about the size of the elbows used to create them, since any uphill routing at all will prevent water from draining in. I can get some pictures if you would like.

There are bound to be lots of opinons on how large a pipe to use. Again, going by what Jeff Jewitt recommended, I went with the largest I could get - or more accurately with the largest fittings I could find. Our local Home Depot had 2" copper pipe, but only fittings for their pipes up to 1 1/4", so I went with 1 1/4" mains and 1" drops. Copper is a lot easier to cut to length than iron pipe, and it won't rust. However, you need to be reasonably skilled at soldering.

Good luck with it.

Bill

PS Will you be at the show in November?

Re: Compressed air piping question

Harvey Bernstein (Philly)

>Thanks Bill. The uphill part was what I considered to be the drop as you could tell from my post, I hope.

I'm using 1/2" type L copper which is supposed to be good for this application (and probably the max I can fit in my shop!).

I thought I posted this on the other board. No wonder I couldn't find it!

Yes, I'm planning to be at the show. Looking forward to seeing you there.

Harvey

Oh and Bill

Harvey Bernstein (Philly)

>Thanks for offering the pic. I do remember what your setup looked like except for the vertical part before the connector. I, unlike you, basically have zero clearance above. I have to cut through the plaster ceiling and go up between the joists for each vertical part. That's why I wanted to find out how high it should go, in case I need to replan this.

Again thanks,

Harvey

Re: Compressed air piping question

Jensen

>What show is that, I'd love to see the work you guys do.

Re: Compressed air piping question

Mark Mandell - Gone Round In Jersey

>Harvey,

Please describe your compressor. Small? Large? CFM rating? 4 gal? 20? 60 ort 80 gal? All make a difference in the system.

Frinstance: 60 gal gives plenty of storage volume, so 1/2" type L is fine. 20 gal. (like Bill's) and you'll be considering making extra storage volume in the piping so the unit doesn't cycle too often.

Mark

Re: Compressed air piping question

Harvey Bernstein (Philly)

>Jenson,

Bill was refering to the WOODWORKS show at

FT. Washington, Pa Nov 5-7

Harvey

Re: Compressed air piping question

Harvey Bernstein (Philly)

>Mark,

I have the pretty much std 20 gal 3.5hp (now called 5hp)Craftsman. I'm not doing any HVLP stuff, but if I have to do it, I don't and won't mind driving the neighbors crazy w/ constant cycling ;)

Harvey

Re: Compressor cycling

Mark Mandell - Gone Round In Jersey

>Harvey,

It's tough on the compressor as well, and the air flow gets a "pulse" in it that can hassel air tools. Since you've made a commitment to 1/2", I'd suggest you pick up an extra pressure tank (sell for something like $30 for a 10 gal. size) like those used for "portable air". Pipe that into your system and it will help both your compressor and your electricity bill. You'll also then have enough storage volume to feed an HVLP gun if you go that way later.

BTW don't forget to put a piece of flex hose between the compressor and the piping system to isolate vibration.

Good luck!

Re: Compressor cycling

John Lucas

>Mark

I bought the biggest compressor I could afford but it's still to small to do air sanding. It's a 4.5hp 21 gallon single stage unit. Here's my question. Lets say it takes 2 minutes to refill the tank when it recycles. It recycles frequently when sanding. If I get another tank it won't recycle as often but will take longer to refill. In theory the motor runs the same amount of time. There is of course some rest time inbetween but it probably gets hotter when running because of the longer cycle. Should I get the bigger tank or just let it recycle more often.

I know the best solution would be a bigger dual stage unit but that's not an option right now unless I just happen upon on a killer deal. I'm trying to buy a house and if I get it will install a 220 outlet for the compressor and start looking but that's could be a good while off.

Re: Compressors

Mark Mandell - Gone Round In Jersey

>John,

"Horsepower" is largely irrelevant; that matter only with regard to what you need to run the the compressor pump. It is the "CFM" [Cubic Feet per Minute] that determines what your outfit can do. Air sanders are huge air users. I run a 3 hp (real) 60 gal. Ingersol-Rand unit that puts out 12 CFM on a continuous duty cycle at 90 PSI, but it will not (properly) run an in-line sander or a good quality jitterbug sander as their requirements are usually more that 16CFM.

My information is that your view concerning compressor heat is incorrect; it is better for the pump and the motor to have them run for a longer period of time less often. The heat build on the pump evens out very quickly after start up and the pump, like your car, reaches maximum efficiency when it's warmed up because the parts expand and fit a bit more tightly so you have less leak-back around rings and valves.

Note also that I mentioned "continuous duty." Many units being sold are designed for intermittant operation. Prime examples are the oil-free air nailer compressors. Run one of those continuously and you'll burn it out in a surprisingly short time. The more often your unit runs, the closer it comes to "continuous" duty. This rating is NOT just a function of the electric motor; many motors are so rated. It's the pump that must also hold that rating.

I'll close by mentioning that I saw a GREAT deal in the last Harbor Freight catalogue. This was a 4 hp. 14CFM/175 PSI 60 gal. 2-stage QUINCY unit for less than $900. Now THAT's a very fine unit and if I could find a buyer for my IR at a good price, I'd up-grade as fast as I could dial the number.

Mark

Thanks Mark !

Harvey Bernstein (Philly)

>The added tank sounds like a great idea.

Thanks again,

Harvey

Re: Compressors

John Lucas

>Thanks Mark. I'm always trying to learn more.

Re: MAKE SURE . . .!

Mark Mandell - Gone Round In Jersey

>Harvey,

You have to make very sure that the supplemental tank is pressure rated above the pressure that your system is set up to maintain, and that it has a condensate drain. Being a storage tank, it will tend to condense water vapor from the air going thru your system. This is a benefit as you get drier air moving through your tool, but you will have to keep it drained of water or it will rust out just like your primary tank (which you already drain and keep dry, right?). This will likely involve a bit of plumbing, but it's not difficult

Mark

Re: MAKE SURE . . .!

Harvey Bernstein (Philly)

>Oh Man!!! I'm glad you told me that. If I opted for the 2nd tank I was going to use my 10 gal portable. Apparently it is totally a no-no-no-no.

Well, drainwise anyways.

Thank Mark,

Harvey

Re: Compressed air piping question

Scott Thorburn

>Harvy, I know that when we installed the air lines at work we installed them in the ceiling for no other reason other than to get the pipeing out of the way. In each room we had one drop and then piping around the room with connections to work stations. The drop continued about 12" below the Tee that the pipes around the room come off of.At the bottom of the drop is a drain valve.

As Mark mentioned It is important to drain your unit to keep it dry.

Re: Compressed air piping question

Bud Gabaree

>If you haven't already purchased your pipe, consider Sch. 40 PVC. I know the purists out there will say it isn't proper for compressed air lines, but why not? 1/2" PVC is rated at 600 PSI, 1 1/2" at 330 PSI. I don't think you'll generate that much pressure.

I've networked my shop with PVC and it has performed well for a number of years now. In fact, we use it for air where I work as well.

It's cheaper and easier to install than black pipe or copper.

If you have a large shop, or a lot of long runs, tie the ends of your pipe system together. In other words make a loop instead of a tree with branches. Pressure will be consistent at every drop.

If there are any experts out there, maybe they can tell us why PVC should not be considered.

Bud

Re: Why PVC shouldn't be used.

Al Crandall

>I'm not an expert like you requested, but this proposed solution pops up often. If you impact black pipe or copper pipe while it is pressurized, you will get a result varying from nothing to a possible dent to a very loud leak which in itself is normally harmless. If the accidental impact occurs to PVC, the result has been, in some documented cases, highly energized flying shards of sharp plastic. PVC pressurized with a liquid and PVC pressurized with air are likely to react differently when impacted.

Re: Expert . *LINK*

Mark Mandell - Gone Round In Jersey

>Bud,

The link is to O.S.H.A.'s site and statement of position which PROHIBITS PVC pipe for all pressurized air installations.

Please seriously consider replacing whatever plastic you have in your system. Consider as well that were you or a visitor to be injured by bursting PVC pipe, your insurance coverage might well be questioned or denied for violation of the OSHA standard (even though OSHA may not directly apply to homeowners or one-person shops, some building codes incorporate OSHA's requirements "by reference")

Mark Mandell


OSHA No PVC

Re: Expert .

Fog Tanner

>Interesting that none of the reports mentions what schedule PVC was used. That really renders the reports almost worthless as they make a general statement and nothing truely specific. But that is typical from what you get from the guvment. I would be more interested in a qualtative report detailing the schedule, size of pipe, pressure, and environment. If the wrong schedule is used or it is too large it will explode.

When I bought the compressor for my shop 16 years ago, the compressor place sold me schedule 80 pipe and warned highly against sch 40. Sch 40 will not take the pounding or bursts produced by the compressor. They also showed me a tank that had gotten some rust in it. The steel tank was peeled open, a veritable bomb and much worse than any pvc pipe. The thought of that tank has stayed with me and I always treat compressed air with a lot of respect. And my current plan for my second compressor is also sch 80 pvc.

Re: Look again, Fog

Mark Mandell - Gone Round In Jersey

>"American Society for Testing Materials (ASTM) D1785-86, Standard Specification for Polyvinyl Chloride Plastic Pipe, Schedules 40, 80, and 120, and ASTM D2513-86a"

Your Sch 80 is also prohibited on the recommendation of the pipe manufacturers' association. Note also that the prohibition is on PVC. There is pressure rated ABS pipe in use. Of course you're welcome to run your PVC inside steel shielding, but why bother.

BTW the info I discovered when shopping compressors is that there have been "0" (none) violent failures of pressure tanks due to rust. Was told, however, that some dealers like to have an old ruptured tank (always rusty) around to help sell the heavier and more expensive equipment. Rust will thin the tank at the bottom and then pin-hole causing a leak; it will not cause a explosive rupture of the vessel. That, as far as I could find out is caused by overpressurization, fault lines in the steel, thin tank material, shoddy welding, or trauma and any combination of those 5. Prime reason for buying a unit with an ATSM-rated tank.

Mark

Re: Look again, Fog

Fog Tanner

>Mark,

I saw the line in reference, but did not see any of the reports stating the failing pipe and under what conditions. I guess many years of working in data processing where I have to question all the conditions that cause a failure and not blindly accept a generalized statement. Had OSHA publicized more specifics, I would tend to place some faith in their statements. Or as much faith as I can place in a government issued report. Being a boomer, that's hard to do.

Interesting bit of info on the tank failure, had never heard of that before. Since we are in differet parts of the country, that must be a common sales hipe in the compressor business. But, they weren't trying to sell me a heavier tank as it was ASTM rated, only impress me with draining the tank.