Rapid Air Max Line---Any users, any thoughts?

[Peter Quinn]

I'm building a new garage, the old one has been demo'd. I'm planning to put a 100A service in this detached building, wiring up the compressor out there and piping the air back into the basement shop. My wife hates the noise, especially when I'm spraying. I may be spraying more in the new garage in the future, the old one was a dirty pit not suitable for that sort of work. Anyone using the rapid air system? I claims its approved for direct burial , I'm going to have a service trench for power, wondering if this stuff should go in conduit, or can it go solo? Any input appreciated.

[Peter Stahl]

Never seen this system. My BIL use his own version of it. He had all the fittings and tools to make custom lengths of air hose and ran it to a couple places in his garage. If it's rated for the pressure it should be ok. Just don't leave it pressured up when not in use.

[Stephen Cherry]

I've used tubing like this in the past, different brand though. Generally works great. If you are spraying, I would have a tank, as well as coalescing filter and regulator inside the house. The ground would act as a good cooler.

[Jim Neeley]

Great question! I expect to be installing air distribution in my shop this winter and am seriously considering the Rapid Air system. I'll be following this thread closely; thanks for starting the thread!!

Jim

[John R Hoppe]

I'm building a new garage, the old one has been demo'd. I'm planning to put a 100A service in this detached building, wiring up the compressor out there and piping the air back into the basement shop. My wife hates the noise, especially when I'm spraying. I may be spraying more in the new garage in the future, the old one was a dirty pit not suitable for that sort of work. Anyone using the rapid air system? I claims its approved for direct burial , I'm going to have a service trench for power, wondering if this stuff should go in conduit, or can it go solo? Any input appreciated.

I see several "Red Flags" in this idea. First, are you spraying finish inside your house? Are any of those finishes solvent based? Spraying indoors will spread vapor and mist through the house and will probably cause problems with insurance should anything bad happen.

On the air distribution portion of the post, while the Rapid Air system works very well (they are a customer for my line of safety air couplers) I would not recommend using it as described. Since compressed air always contains moisture, and that moisture condenses out when the temperature drops, running air lines underground creates a synergy of bad events. As the air travels into the cool underground section of the line, the water vapor will condense to liquid and the lower section of the line will behave much like the trap in your kitchen sink drain. Water will puddle in the trap and you will have continuous issues with water in the line. Another issue is that if anything ever goes wrong and needs service you will have to dig up the entire line to find and repair the problem.

I suggest that you revise your idea to take the air line up from the compressor, run it overhead to the house, then drop it to a water trap/filter to remove the water and compressor oils after it enters the shop at the point of use. That will ensure that you have clean dry air to use and not an intermittent squirt gun.

[Jeff Monson]

Peter, I have the rapid air system in my garage. It took about 20 minutes to plumb it, very quick, easy and the fittings do not leak. I purcased the kit and added a couple of drops that did not come in the kit, also had to order a couple extra 90's. The line is fairly rigid, it comes coiled up, so getting it straight is kinda a PITA. The wall on the tubing is not super thick, mabe a little over a 1/16"?? Other than that I would see no problem putting it in the ground, a conduit may be the best gaurantee against a puncture. I'm really impressed with the ease of the system, especially if you want to add to it or reconfigure it. Let me know if you have any more questions.

[Fred Belknap]

Peter I have the Rapid Air system. I leave it pressured up most of the time with no problems. Like was stated it is pretty stiff to get unrolled. I went with the 3/4" but I think the 1/2" would have worked fine. I used clamps to hold it to the walls of the shop, no conduit. I do have a small leak I can't find, my compressor kicks on about once every day even when not used, it may be in the compressor.

[Peter Quinn]

Sounds like good stuff. I'm spraying only WB coatings in a sealed zip lock type room with pretty strong exhaust and filtration on that to catch any dry over spray. WB coatings dry pretty fast in the air. I will probably keep spraying in the basement in winter as its presently easier to heat. Contractor suggested putting the air line in a conduit, doesn't sound like fun, but maybe more prudent. I'm using the 3/4" line, it's about 35' to the house, about 90' to the spray room. I am concerned about condensation in the lines, maybe I can pitch it to a dirt leg inside the house rather than create a trap? I'm planing to put a 35gal storage tank in line just before the spray line to avoid any pressure drop, and a good water filter at the entrance and ahead of the spray line too. I've ordered the piping today so worst case I just blew $200. An over head line is not possible for aesthetic reasons.

[Fred Belknap]

The cheapest place I found was Amazon.

[Stephen Cherry]

On the air distribution portion of the post, while the Rapid Air system works very well (they are a customer for my line of safety air couplers) I would not recommend using it as described. Since compressed air always contains moisture, and that moisture condenses out when the temperature drops, running air lines underground creates a synergy of bad events. As the air travels into the cool underground section of the line, the water vapor will condense to liquid and the lower section of the line will behave much like the trap in your kitchen sink drain. Water will puddle in the trap and you will have continuous issues with water in the line. Another issue is that if anything ever goes wrong and needs service you will have to dig up the entire line to find and repair the problem.

I suggest that you revise your idea to take the air line up from the compressor, run it overhead to the house, then drop it to a water trap/filter to remove the water and compressor oils after it enters the shop at the point of use. That will ensure that you have clean dry air to use and not an intermittent squirt gun.

One of the basics of compressed air supply is that the coalescing comes after cooling. You can remove all of the liquid air droplets from the air, but if the air is still hot from the pump, the water will fall out after it cools.

Sending the air on a little underground trip would do about the same thing as a high dollar aftercoller, BUT, you need a tank in the house to let the droplets of water settle, and a coelescing filter, and a regulator.

If it were me, I would look at copper for better ground contact.

[Peter Quinn]

One of the basics of compressed air supply is that the coalescing comes after cooling. You can remove all of the liquid air droplets from the air, but if the air is still hot from the pump, the water will fall out after it cools.

Sending the air on a little underground trip would do about the same thing as a high dollar aftercoller, BUT, you need a tank in the house to let the droplets of water settle, and a coelescing filter, and a regulator.

If it were me, I would look at copper for better ground contact.


3/4" copper is a possibility given the distance. Direct burial? Bendable? Sweat lines?

[Sam Layton]

Peter,

I would run your air line in conduit. If possible, depending on bends, etc, run a large enough conduit so you could pull new pipe if necessary, and if the pipe is flexible enough. In my shop to help control the condensation in the air line, I ran a cooling manifold after the air left the compressor, and before the air reached the air drops. I ran my air line in the attic, and ran about 50 feet, draining back toward the compressor, to a water trap, before the line went to any drops. My thinking, is that the 50 foot run allowed the air to cool, and any condensation would run back toward the compressor/water trap. Seems to work good.

In your case, I would run the air line from your compressor, into the attic for about 50 feet, all draining back to the compressor/water trap, then back down the wall and underground to your shop. My thinking, is that when the air goes underground, it will be cool. Just thinking out loud. Also, I like the idea of having a storage tank in the shop.

Sam

[Stephen Cherry]

3/4" copper is a possibility given the distance. Direct burial? Bendable? Sweat lines?

I don't know if you can bury copper, I think that it is Ok for water, but not sure. Direct bury to me is an ideal situation. From a previous life, I like good compressed air, and cool air is good good air. One thing to remember is that conduction of heat is much better to a directly contacting solid (the ground) than to air.

One time I saw a construction crew redo a soldered copper compressed air system. The idea was that you want compression fittings on air line.

[Larry Edgerton]

My concern with the plastic is that it is hard to keep it flat, and that you may end up with a water trap in the middle distance. I would probably run it in 3" PVC myself so it could be replaced if need be, and run it below frost line so that the inevitable moisture trap would not turn to ice, especially at places where there will be traffic on top of the line in the winter. Not sure what your frost conditions are there, here they are 4'.

The PVC line would allow you to run other things in the future [intercom, water,etc.] and you could blow warm air through it if it ever did freeze up.

I am going to be doing the same thing at my new house/shop so will be interested in your final answer.

Larry

[Peter Quinn]

I spoke to an engineer from Rapid Air about the details of my air line burial plan to make sure it was acceptable. He told me it is better to go below the frost line but not essential, it won't hurt the pipe to freeze. I'm putting this in a service trench with a service entrance cable in another conduit, which is required to be below 18" deep, so I'm not planing to go 48" if avoidable. I was told the water molecules will mostly go along for the ride, they will cool and get "heavy" as they pass through the earth, but they mostly wont turn liquid until they hit the inside. He suggested running it in conduit was a safe plan to isolate it from any earth movement caused by frost heave. I guess I'll have to slide the conduit over the line as I go, don't think I can snake this stuff after the fact. He recommended a drop down right inside the basement with a purge valve to get any water out of the line before each winter just in case, to pull off of that with a "T" to service the main air line, and a storage tank inside with a drain. A water separator is also important. The "trap" theory from plumbing is not particularly accurate for this scenario because "traps" exist on gravity systems like waste lines, this is a pressurized system. Think potable water lines. Do they ever get trapped by low points in the copper or pex? Not in my experience, and they mostly max out at 70PSI. When an oil line gets plugged on a heating system they purge it with a compressed air charge. I've heard of pipes carrying liquids becoming air locked if one end is closed due to vacuum, but this is an open system when air is passing through it. Best way to clear the line of water? Put 150 PSI of air behind it and push....I can do that!:D

Sounds like the hardest part is going to be getting the compressor back out of the basement. Don't recall that being much fin going down and I had gravity on my side for that one. It will be next spring before the building goes up, but the foundation goes in this month, so the conduit and air lines must too. I'll try to post next year when I get this thing together.

[Jim Andrew]

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.

[johnny means]

Oh, now you went and did it. PVC air line is a 4 letter word around here.:eek:

[Chris Parks]

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.

[Kelby Van Patten]

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.

[Jim Neeley]

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.

[Larry Edgerton]

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.:cool:

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

[Jerry Bruette]

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

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.

Jerry

[ray hampton]

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 ?

[Peter Quinn]

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.:cool:

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?:D 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?:eek:

[brian c miller]

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

[Peter Quinn]

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.


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.

[Peter Quinn]

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

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.

[Michael W. Clark]

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.