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cab 02-25-2006 08:32 AM

Flexible Pipe from Compressor to Solid Pipe?

Now that I have an air compressor I need to plumb some solid metal line (copper of black pipe) in the garage. I see several folks recommending a flexible metal line from the compressor to the start of the metal pipe to isolate the vibration of the compressor from the line? Where do you get this line?

My compressor has a 3/4 inch outlet to which I have attached a 3/4 inch ball valve, and I plan on using 3/4 inch copper pipe so obviously I want a 3/4 inch flexible hose of some kind?

In addition, where do you guys hook up your air regulator - at the tank's ball valve outlet or at the end of the metal lines where the rubber hoses connect?



Paul51 02-25-2006 08:52 AM

compressor connection
The point where you want the filter is as close to the end use. If you have a garage where you will do painting at that area is where I would put a filter,if the distance from the compressor to the use point is of distance the copper line will trap condensate or water. A rule of thumb is where ever there is a drop you should put a filter or drier as heat is generated at the compressor and sent out to the use points. Sometimes you will notice when you use air tools they exhaust moisture as you first start,you don't want that if you are painting. As far as flex isolators there are many outfitters you can look one good source is they have everything you need.

Henry Highrise 02-25-2006 09:57 AM

Just get you a short hydraulic hose ( 2 to 3 ft.) with NPT fitings of the size you need on the ends. A hydraulic hose is made to withstand 3000 psi so it will hold the air pressure from a compressor. You can get one at Tractor Supply Company or most of your NAPA stores have them also.

66GMC 02-25-2006 11:15 AM


Originally Posted by Henry Highrise
Just get you a short hydraulic hose ( 2 to 3 ft.) with NPT fitings of the size you need on the ends. A hydraulic hose is made to withstand 3000 psi so it will hold the air pressure from a compressor. You can get one at Tractor Supply Company or most of your NAPA stores have them also.

The problem I see with hydraulic hose is that it isn't designed to take that kind of heat. Air brake compressors on big trucks use a braided hose of some kind, but I'm not sure of the size (I'm thinking only about 3/8" or 1/2" ID). I had a truck driver stop in that had attempted to use hydraulic hose, but it had burnt off.

Small compressors usually just use a coil of copper hose to allow for vibration and to dissipate heat, but again, we're talking about 1/2" dia.

Someone like Eagle Compressors should be able to recommend & supply the correct part.

OneMoreTime 02-25-2006 12:01 PM

Swing joint
we install swing joints which are made with three 90 degree street ells on each end of a short piece of pipe..this will absorb any movement you are likely to have..


Centerline 02-25-2006 03:44 PM

The flexible hose can be purchased anywhere you can find gas appliances. I've used a 24" flexible metal connection that I purchased at Home Depot from my 80 gallon compressor to 3/4" copper lines for several years now and it works perfectly and has never leaked.

39 chev 02-25-2006 04:19 PM

flexible pipe to compressor
I have been runnung a hydraulic hose from my compressor tank to my air line pipe, and have not had any problem with it. There should certainly not be enough heat at the air outlet on your tank to harm a hydraulic hose.I have had mine this way for 7or 8 years and have had no failure.

Henry Highrise 02-25-2006 06:54 PM

I have ran a hydraulic hose on mine for over 20 problem. It is a 3/4 in. hose, double stainless steel braid.

66GMC 02-25-2006 07:47 PM


Originally Posted by Henry Highrise
I have ran a hydraulic hose on mine for over 20 problem. It is a 3/4 in. hose, double stainless steel braid.

I'm sorry guys ... I think I have misinterpreted what "cab" had asked in the original post of this thread.

I thought he was talking about installing a hose between the compressor head itself and the INLET to the tank. Temperatures at that point are very hot.

Now I understand that to be a hose from the OUTLET of the tank to the metal pipe used to supply the shop with air. :embarrass


cab 02-26-2006 07:40 AM

Thanks all - after trying several local places yesterday (including Home Depot, 2 Napa Stores, etc.) , I ended up ordering a 2 foot section of 3/4" hydraulic hose and some swivel fittings from Northern Tool (ironically not available in the store itself which I also visited) - total cost of about $25 or so. I've also started mapping out my copper pipe layout. As a note to those of you thinking about buying your first compressor - plan on spending some serious extra cash before you can actualy start USING your new compressor - i.e. 230 volt outlet install, piping, connectors, ball valves, filters, regulator, hoses...oh, and you might even want to buy an air tool! ;)



bowtiedude69 02-27-2006 02:21 PM

Flex line
I used plastic line that is used on truck air brake application it is rated at 300 psi uses npt fittings and compression sleeves make sure you get for airline. You can get this stuff at most NAPA or Carquest stores. As far as heat I have used the same line for 14 years. The fittings are more expensive but reusable and they make 3/4" and 7/8". This stuff last for many years on trucks a compressor hookup will be easy.

robs ss 02-27-2006 10:52 PM

Heres some I just posted on another site

Heres a little more on air lines.

TP tools and equipment is one of the largest companies that I know of in regards to sandblasters etc.

If you go to there web site they have a short article on air lines.

It's under


airline hookups

Minimize moisture in your air lines with metal piping

They mention black pipe, galvanized pipe, plastic pipe and copper pipe, not saying that there the last word on this subject, but running air lines, is a big job, and most of us can't afford elaborate air dryers and all that, but a little research before you put them in, will be well worth the few minutes it takes to check it out.

Condensation in air lines can cause a lot of problems down the road, and paint and primer are not cheap.

Anytime an amateur like myself can eliminate any type of problem with the equipment, then that makes less room for error later.

Were in our garages alone, when were painting we can't just holler at a coworker and say something is wrong with the way this paint is going on, in a large body shop you can probably get answers right away, we have to shut down and get on the computer.

Putting in air lines that will keep the moisture down is not an easy task, but if put in right at the start, it's definitely a time and money saver.

Just an old mans two cents.



robs ss 02-27-2006 11:05 PM

Chris, heres a little more

When you run your line from whatever pipe you use, try and slope it down from your hard pipe, try to eliminate any flat areas in any of your lines, if you look at the line on my site, you'll see how I came off the top of the hard pipe and sloped it down to the filters.

It's the website on the previous post


robs ss 02-27-2006 11:31 PM

Heres some more, I'm copying and pasteing from my old posts, so bare with me, I'm not that good with a computer, I guess you're still reading or have you heard enough, anyway.

One more thing here, you will or should have filters at the end of your hard piping, just before it goes into the rubber air hose.

I would drain them every day, heres why.

The last compressor was three years old, I go to drain the filters, and after I turned the little wing nut, I noticed my fingertips felt slippery, so I shut them off, turn the air pressure back up, get a clean white rag, crack that wing nut open and blow it into the rag, it's a little dark colored, and I put it up to my nose, and I could smell the oil.

I run three sharpe f-88 filters right in a line, I took the filters out, the little white do jobs, the first one is dark brown, second a little brown, and the third was close to white.

I have one more f-88 in the paint roon, that one is pure white, so by draining these every day I saved loading my air lines up with oil.

I changed out the compressor, also look at your instruction manual and see if it mentions a duty cycle on your compressor, if it does, I would adhere to it, ask me how I know this.

I run a large bead blaster, a pressurized and siphon sand blaster, I have fought water problems, until I almost bought an air dryer, I went with about 75 feet of 3/4'' black pipe, my water problems went away without buying an air dryer.

You allready know, by listening to you, that it takes some planning to lay all this stuff out.

Hope some of this helps you or somebody out.


oldred 02-28-2006 04:09 PM

Probably the most important factor in running the main line, with the exception of material they are made of, is to not have any low spots ANYWHERE in the line unless it has a collection drain. If there is any low spot (such as a dip in the line) where water collecting on the pipe walls will drain down and collect in the pipe it self you will have a big problem. Nothing will happen at first but as the water collects it will begin to restrict the air flow at which point the air will pick it up and cause it to be expelled in surges, not just droplets but some times in large amounts depending on the size of the low spot. When this occurs it will last for only a few seconds and then everything will seem normal with no more problems until the water collects to the critical point and then the cycle will start all over again. I have seen this happen several times and it can be a real headache since most of the time it will overwhelm the separator and simply spray water at the worst possible times. :pain:

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