I have a relatively cheap 8 gallon compressor but still would like to run some air supply lines including to avoid having to drag the compressor along:
- 1 to central workbench area (20 ft)
- 1 to top of garage bulkhead (40 ft) to facilitate outdoor projects and filling bicycle or car tires
- What piping material should I use? (copper? plastic? rubber?)
- What diameter piping would be best given length of run and size of compressor?
Copper if price is no object. Black pipe if price *is* important.
Max
Actually the rubber hose would work and probably be the easiest to install. Or the cheaper air hose from HD, IIRC $20 for 100' with male ends.
Anything but PVC for the material.
No one addressed the size, yet, but here are my thoughts on it. For the short run, it doesn't make much difference. Anything from 1/4" on up will work. As you get into the longer runs, the smaller sizes wind up hurting you in the flow department (CFM), even if you are able to keep a reasonable pressure. And an 8 gallon compressor is unlikely to get you more than 100 PSI (not because it's 8 gallons, but because compressors with 8 gallon tanks usually don't have a lot of oomph), and a longer run at small diameter will be something less than that. Okay for sprayers--not so hot for bike tires.
The thing about the longer run, is that it winds up being a storage manifold as well as a delivery manifold, and if you use 3/4" or 1" pipe, you can effectively increase the capacity of your compressor.
For example (and assuming my math is right--I'm sure someone will check it), 3/4" pipe has a cross-sectional area of .4415 in^2 and consequently, a volume of 5.29 in^3 per foot. A 40' run, then, would have 211.95 in^3, or approximately .9 gallon.
Similarly, a 1" pipe has a cross section nearly double 3/4" (.785 in^2) and a volume of 9.42 in^3 per foot. Your 40' run yields more than 1½ gallons (1.63) in 1".
Note that that extra storage applies to both the outlet at the end of the 40' run and the end of the shorter run--it's in the system.
The larger the pipe the more storage you have, but it also takes longer to come up to pressure.
Do NOT use PVC. It is a danger and prohibited in industry by OSHA as it can explode and make shard of plastic flying around.
Copper is the easiest to work with, but copper prices are high. I'd look at buying some 3/4" air hose for the long run, 1/2" for the short run.
blueman wrote in news: snipped-for-privacy@consult.pretender:
*snip*
Just a somewhat random question... Has anyone given any thought to using Pex? You know, that stuff that's replacing copper for water piping in new construction?
Just a thought...
Puckdropper
Thanks for the detailed exposition! So, I guess I'm thinking of biting the bullet and using copper. I'm trying to decide now between 1/2" and 3/4" (while I appreciate the extra manifold capicty of 1", I'm not sure it is worth the extra cost or bulk).
- Would I see much difference between 1/2 and 3/4"? i.e. Would it be "penny wise, pound foolish to put in 1/2" now just to save a few tens of dollars on copper piping and fittings?
- Would type 'L' be preferable to type 'M' or is type 'M' good enough for air at pressures of 90-125PSI?
Now I know from simple geometry that 3/4" has a tad more than twice the area of 1/2" but I'm not sure of how to do the Ohm's law type math to see what type of pressure drop I would be seeing with 1/2" vs. 3/4" for typical uses.
Assume average pressure of 100PSI at the tank with an average steady state 4 CFM.
If I want to make up a short (1-2') section of flexible hose to go from the compressor to the fixed pipe run, can I make (or buy) a short run out of easily accessible materials? (i.e. what types of hose material and what type of fittings)
RE Subject
For a small shop, use 1 black iron pipe, pitched 1/4/ft with a derain petcock at the low point.
Buy 1 nipples, 60" lg, then couple together with 1x1x1 tees.
Bush down side tapwith 1x1/2 reducer bushings.
Assemble with side tap facing up, then use 2, 1/2" street ells to turn
180 degrees to point down.Hang hose from street ell
Isolate pipe from compressor with a 3-6 ft 3/4" rubber hose.
Have fun.
Lew
Whips are commonly available. They come with the ends attached and are far superior to trying to make your own. Cheap too. If you have a Harbor Freight near you, just pick one up there. By the looks of some of your questions ("what types of hose material and what type of fittings"), it appears you're not too familiar with what's out there. I suggest you head out and take a look at what is on the market. You'll answer more of your questions with a quick look than you'd think.
As for your pipe diameter - just go with 3/4" all over and you'll be fine. No need to step down at some distance as you'll likely never be using air in two places at the same time where you really need to worry about even pressure at each location. Do put in water drops as previously suggested.
I'm sure there are stats and such to back this up, but personal experience says "bunk."
We used 3/4" SCH40 White PVC piping all over our shop with drop/drain lines at every "wall outlet" to collect and allow us to drain the moisture.
We used a big old eighty-gallon unit with a 5HP motor and heavy-duty two-stage compressor we got from a body shop that closed down.
We're talking nearly ten years of use w/o issues and moved the system to a new warehouse where its been doing nicely for seven more years.
We run air tools and spray materials.
I've heard this "No PVC" stand before - but no practical experience with issues that would preclude its use.
Surely his piss ant compressor would put less strain on the piping than our setup.
As for the HFT tubing solution - it strikes me that, if you ran it so as to be able to "pull" it out in case of a problem, it might be fine for this application (although the CFM /air flow would be impacted. But I use about 100' feet of it with my air nailers off a Portable PC w/o issues. BTW, the 3/4" PVC provides extra storage - like adding a second tank.
Enjoy
big boxes also sell air hose in bulk. a couple of fittings and hose clamps would also work.
According to a catalog I have, Schedule 80 PVC is good for a max of 200psi. The media should not matter since it is at ambient temp.
Whatever is purchased off the shelf should have a psi rating on it.
Before hauling rigid pipe though, I would look at what he is runing.
He might be able to get by with pulling a 3/8" semirigid poly tube as well. Less joints to make up and less places for leaks.
I used a 1/2" poly from the compressor in my garage into a hobby room and my shop. Also pulled a 1/4" line connected to the blowdown port on the bottom of the tank and ran it to the work shop so I could drain the water without going to the gagrage.
I have had this arrangement in the basement for about 7 years with only one leak caused by the cable guy last year.
I used heavy gage 2" PVC to create a header and reservoir of sorts in the shop.
I've used several of these and been happy with them:
L would be preferred, but M would be acceptable.
At 4cfm you would not see a difference between 1/2" and 3/4" at
100psi. At 14CFM you might. ** Posted fromHoosierpopi wrote: ...
Below link outlines the issue and at least one alternative--
SUBJECT: Safety Hazard Information Bulletin on the Use of Polyvinyl Chloride (PVC) Pipe in Above ground Installations
The Dallas Regional Office has brought to our attention a potential serious hazard existing with the use of polyvinyl chloride (PVC) plastic pipes for transporting compressed gases in above ground installations. An employee in a Texas plant was injured recently by a rupture in a PVC compressed air line. Plastic projectiles from the point of rupture caused lacerations of the employee's hand. This is noteworthy because the Plastic Pipe Institute, in its Recommendation B dated January 19,
1972, recommends against the use of thermoplastic pipe to transport compressed air or other compressed gases in exposed plant piping. ...Furthermore, sections 842.32, 842.43 and 849.52(b) of the American National Standards Institute/American Society of Mechanical Engineers (ANSI/ASME) B31.8-1986, Gas Transmission and Distribution Piping Systems Standard, limit the operating pressure of plastic piping distribution systems to 100 pounds per inch (psi) and prohibit the installation of such systems above ground except where ". . . the above ground portion of the plastic service line is completely enclosed in a conduit or casing of sufficient strength to provide protection from external damage and deterioration."
...
Size/HP of the compressor aren't the issue nearly as much as the operating pressure and to a somewhat lesser degree the piping sizing (larger diameter --> more schrapnel in case of fracture). The OSHA mandate is for >100 psi systems I believe.
Regarding a specific system and experience, it's only an issue when it becomes one; unfortunately when that happens it could cause a significant injury.
It's one of those things where I'm not going to tell anybody they have to do something but it is imo irresponsible to recommend it.
I think UV, ozone, and fume exposure can greatly affect PVC.
I've built items that literally crumbled after a few years.
Hit it in a area exposed to sunlight with a metal tool while it's pressurized.
It's kind of like running into someone who rides a motorcycle and says "I've never crashed so why wear a helmet?".
Lucky you.
Kind of irresponsible to advocate its use based on personal experience when there are "stats and such" extant, however, don't you think?
This would be one of those areas where I would have counseled erring on the side of silence.
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