Would not schedule 40 pvc make a good air line? If you put in a big enough pipe, and sometime in the future you got a leak, you could possibly put a line inside it. A shop I worked at years ago had pvc air lines.
Member
Would not schedule 40 pvc make a good air line? If you put in a big enough pipe, and sometime in the future you got a leak, you could possibly put a line inside it. A shop I worked at years ago had pvc air lines.
Contributor
Oh, now you went and did it. PVC air line is a 4 letter word around here.
Member
It might be pressursed but that does not equate to an airflow fast enough to prevent condensation unless you are using high demand tools. I would like to hear your thoughts on how it went in twelve months time.
Chris
Everything I like is either illegal, immoral or fattening
Member
I have used a Rapid Air system for about six months. It is a great solution -- easy to install, very effective, and reasonably priced. As others have said, it comes coiled and wants to stay coiled, so it is a pain to get it straight.
Perhaps because of the constant tension as it tries to unstraighten, I have ended up with a couple of leaks at the fittings. They were easy to repair. The leaks did not start until months after I installed the system, and I could hear them immediately.
If you go underground, make sure everything can readily be removed & replaced if necessary.
Member
Peter,
FWIW, I agree with your burial however what you were told comparing the condensation of water in an underground line being comparable to all water is plain phooey.
I design engineer for the oil & gas production industry. Water dropping out of air in the pipe due to cooling is directly analogous to liquids dropping out of wet (just produced and not dried) natural gas in a pipeline. What you will experience is periods of all vapor (air) flow, with periodic slugs of water coming through, as enough builds up in the line for the air to force it out. If you are convinced, based on where you live, that freezing of this moisture will not be a problem, I would recommend running the air into at least a small air tank prior to distributing it in your shed. This would allow the slug of water to "drop out" in the tank, where it can be drained. For a low-budget approach, perhaps you could buy someone's old compressor (that didn't work), and strip off the compressor. This would leave you with the tank, a drain valve, a relief valve, and separate inlets and outlets to minimize the amount of moisture carry-through you get into your shop system. Even so you'll want a coalescing filter (and perhaps a desiccant if getting a trace of moisture in your spay is bad) before shed distribution.
Just my $0.02.. YMMV.
One can never have too many planes and chisels... or so I'm learning!!
Contributor
Peter I would like to hear from you when you get this up and running, pros and cons. Our new home will be plumbed for compressed air [copper] and rather than have a seperate compressor in the house @125psi [single stage] I have been contemplating a similar setup to the big compressor in the shop 75 feet away @ 175 psi.
Some of my concerns were ice, pressure loss which would probably not be a problem but I like to worry, and a blowout under ground.
A shutoff in the shop for that line seems like a good thing when not in use so if there is a undetected leak underground it does not blow the compressor. I had a compressor meltdown in the old shop and do not want that again.
An accumilator tank in the spray area would be good. On site I do a lot of spraying and the air hose is up to 150 feet long. As you get farther away it gets harder to control the spray precisely. I bought one of those 20 gallon air storage tanks and keep that by the gun and it solved the problem.
The ice thing I wonder about. I thought of using one of those direct burial heat tapes with the stainless sheathing to heat the inside of a pipe the air line is buried in. Would only need it in the coldest months, and only when air was needed. Probably overkill though, but I am the king of overkill.
Anyway..... I am curious about the plastic. A blowout when I am not home and I forget to turn off the compressor[all the time]concerns me. Last time with the meltdown it was the pressure switch that malfunctioned and the compressor caught on fire in the middle of the night. My new IR compressor has a thermal overload shutoff. And I am curious about water issues.
I'll be watching.....
Larry
Contributor
Larry if you're worried about a blow out toasting your compressor you could install a pneumatic fuse right after your compressor outlet. It'll shut off the flow if you have a blow out down stream. We've been installing them on all of our new hose reels at work in case of a blow out or cut air line. I believe we're buying them from Grainger and they're reasonablly priced.Originally Posted by Larry Edgerton
Jerry
Confidence: The feeling you experience before you fully understand the situation
Contributor
the water in your underground line will run to the lowest point of the line and freeze when you are not using the air, adding a heat tape to the airline will help, will a heat tape perform better on metal line or PVC line ?
[OP]
Member
Peter I would like to hear from you when you get this up and running, pros and cons. Our new home will be plumbed for compressed air [copper] and rather than have a separate compressor in the house @125psi [single stage] I have been contemplating a similar setup to the big compressor in the shop 75 feet away @ 175 psi.
Some of my concerns were ice, pressure loss which would probably not be a problem but I like to worry, and a blowout under ground.
A shutoff in the shop for that line seems like a good thing when not in use so if there is a undetected leak underground it does not blow the compressor. I had a compressor meltdown in the old shop and do not want that again.
An accumulator tank in the spray area would be good. On site I do a lot of spraying and the air hose is up to 150 feet long. As you get farther away it gets harder to control the spray precisely. I bought one of those 20 gallon air storage tanks and keep that by the gun and it solved the problem.
The ice thing I wonder about. I thought of using one of those direct burial heat tapes with the stainless sheathing to heat the inside of a pipe the air line is buried in. Would only need it in the coldest months, and only when air was needed. Probably overkill though, but I am the king of overkill.
Anyway..... I am curious about the plastic. A blowout when I am not home and I forget to turn off the compressor[all the time]concerns me. Last time with the meltdown it was the pressure switch that malfunctioned and the compressor caught on fire in the middle of the night. My new IR compressor has a thermal overload shutoff. And I am curious about water issues.
I'll be watching.....
Larry
The max air line came in this week, it looks pretty good. It is similar to the aluminum core flexible gas pipe they use for propane and natural gas now, but its blue, not yellow. So its not all plastic, but a sandwich of HDPE inside and out with aluminum core for strength. Its a well proven technology for gas transmission, apparently it can be used for c02 lines too, so if this air thing doesn't work out I could maybe put a beer tap in the basement and keep the kegs cold out in the garage?If it blows, it doesn't shatter like pvc. I was told it can certainly take a New England winter, operates down to -40 degrees safely, rated for 200PSI IIR. I'm going to bury it in a 3"-4" conduit with an extra leader so I can snake another line should it ever fail. It will be one continuous piece from end to end, so I see that as a limited possibility. I don't see ice as a problem here. By the time we get deep ground frost the RH is in the low 20% range, so the compressor runs pretty dry in the winter anyway. I'm going to throw a high flow water separator in line in front of the branch that goes under ground, and the storage tank on the other end will act as more of a condenser than the HDPE line will. Nothing insulates like plastic! We had a compressor line blow at work a while back and take out the pump, it ran all weekend and seized. Now its on a timer so it shuts down after closing, comes back on in the morning. My Dad did the same thing to his after blowing one up, so that might be a possibility too. I like the idea of a flow detector in line, I have something similar on the washing machine and toilets in my house. I won't have this done until next summer, but the conduit goes in next week. Footings are mostly dug, should be pouring next week, I'm excited. Its not only a garage, its going to be a spray room, and 300SF of additional assembly space with 9' ceiling height, and after working in a basement with 7' ceilings, thats huge. My wife thinks we can park a car in there, but I don't see how?
Member
Why not Pex-Al-Pex Line? It's pretty cheap (300' of 1/2" is about $100) and will not sag when use use the proper clip spacing.
It's super easy to run and the fittings are a snap to instal.
BCM
Last edited by brian c miller; 10-03-2012 at 7:59 PM.
[OP]
Member
Jim, I was told water would condense, but not all of it will drop out in the line on a 40' run. Maybe if it were copper, but 2 layers of HDPE are a much better insulator than metal in earth would be no? It will really condense when it hits the cold metal tank on the inside. I have a 32 gallon tank from a dead compressor that will act as a storage tank on the receiving end (basement shop), I'm hoping the water drops out there, it has a drain valve. I'm planning to put in coalescing filter on each end, just before the line goes under ground, and just where it comes out.
Relative to "all water systems" I'm confused? Some had suggested that the water in the line would "trap" the line, and I suppose a chunk of ice could block or restrict the line, but I don't feel water will trap a pressurized system like it would a gravity fed waste line. You've said it will come out in "slugs", I've worked with a bad compressor in humid conditions that bled water at the end line and experienced this. But I've never seen water actually block or "trap" an air line, or even really restrict the PSI available. It follows the path of least resistance, and that is generally out when pushed. Bad for tools, yes. RH is contributing all the water here, and it is typically very low during winter when the ground (and air) freezes so I hope that helps.
In any event I will do what it takes to make sure water does't reach the spray booth, I'm hoping it won't wreak havoc on the underground line.
[OP]
Member
Looks like exactly the same thing but in a different color. Wish I had seen Pex-al-pex first. Operating properties are very similar, tools are the same, fittings are VERY similar. Too late for me, I already purchased, but this may be a good reference for others.
Member
I have seen the slugs of water on larger systems, but have not experienced it on small systems like for a home or small commercial shop. We had as system at work with (4) 500hp compressors feeding the system. Everyday in the morning, a slugs of water would come through the system and we had to blow it down, major pain. We had two issues, not cooling the air enough coming out of the compressors to drop out the moisture (heat exhangers fouling), and also not able to evacuate the moisture that did form. The hot air also shortened the life of the refrigerated dryers. A new water filter (cooling tower water getting dirty and fouling the heat exchangers), dozens of drains, and a new 10,000 CFM dryer later, we fixed it.
Anyway, moisture can be a big pain. If the underground line is the biggest concern, why not evacuate the underground line when you are not in the shop? If you are using the air, it is doubtful that the air will be in there long enough to drop to the dewpoint required for condensation. If I understand, the compressor is in a detached building, so it could stay charged. You only need a solenoid valve in the detached building in the line feeding the basement shop. If you close the solenoid valve, and open a bleed in the basement, the air pressure is evacuated and cannot freeze the line. You can get a 110V solenoid valve and operate it from a switch in the basement. You could also get two solenoid valves, reverse acting so that when you flip the switch, one opens (bleed) and one closes (isolation of the basement line). Just a thought. Maybe you won't need it, but drop a pull rope in the conduit so you could add it later if desired.
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