This page provides information about, and a visitor question page on, plumbing an air compressor.
Information pages are linked below and at the end of the page is an area where questions can be asked.
Site visitors are welcome to offer advice as a comment on all questions.
Plumbing An Air Compressor
- About compressed air lines
- Use PVC air lines for compressed air?
- What to use to plumb an air compressor?
- Connect your compressor to a car tire.
- Does the length of an air hose make a difference in how air tools work?
Air Compressor Broken – What Should I Do?
We get many questions from folks that have a compressor that’s got some years on it, it’s broken, and they can’t find parts.
If you buy an older compressor, that’s a risk you take.
When you buy a new compressor, take the time to find out who the manufacturer is, where they are located, where you buy spare parts and who fixes it under warranty if the compressor fails.
In the era of low cost compressors, that information may be hard to find.
The Big Box stores have a “house brand” of compressor that’s built for them by a faceless company in another country. Every few years they change brands, and all of a sudden they are selling a different brand of compressor, with another source, and the trail for parts and repair of the older unit becomes blurred and ultimately forgotten.
That’s the price we pay for getting cheap compressors.
On the other hand, if you’ve paid $199 for a compressor, does it make any sense to spend almost that amount for a professional to diagnose and repair it when it fails sometime down the road?
It’s your call. But if you can find out the repair details for your compressor when you buy it, then when it ultimately fails, you can make an informed decision about repair or replacement.
About compressor size and plumbing a compressor…
Question: “Im building a vehicle maintenance with four bays. My required compressor pressure is 250 psig. What size of the compressor must i buy? What size of pipe to run the system. Can you give me a hint or formula in solving the capacity of air compressor and the pipe. Thanks”
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We answer…
You need to work backwards from your applications to determine how big a compressor and how to properly plumb it.
How many air tools will potentially be run at the same time in your shop, and what is the accumulated demand of these air tools in CFM and pressure?
After you have determined your demand requirements, then head back to this website, and start here regarding plumbing your shop.
You will want to take a look at these pages about pressure drop as well.
Everything else you will need about sizing and plumbing your compressor you will find on this website.
Careful with low pressure and vacuum
When plumbing compressed air under 25 PSI, or when controlling vacuum, careful that the air valve you pick can operate at those pressures.
A direct acting solenoid valve will operate, regardless of the pressure. Usually these are limited in size, however.
Larger air valves are, most commonly, solenoid air piloted.
This means that compressed air, sourced from that air valves supply line, is being directed through a small valve to operated the bigger valve with compressed air. This type of valve has a Minimum Operating Pressure of around 25 PSI, and the valve will not work if the supply line air pressure is below that, or if you are trying to plumb vacuum.
Most of the solenoid air pilot valves will have an air port on the small direct acting solenoid valve that is piloting it, to allow the plumbing of an external source of higher pressure air. Now, with this supply at a higher pressure installed, the big valve can be used to plumb low pressure or vacuum.
Older parts from older compressors…
Another thought crossed my mind (a rarity) and I wondered if folks would like to have a sort of clearing house for used compressors?
The idea is that if someone has a compressor that isn’t working, maybe they would like to sell if for parts. Or, if it’s working and they don’t want or need it anymore, then they can offer it up for sale.
By the same token, if someone is looking for a specific air compressor to purchase for parts, where do they go.
New Compressed Air Plumbing Solution
Over the years the standard for plumbing compressed air has been black pipe. Yup, the black pipe creates all sorts of problems for the quality of the air, but it has been cheap, and it can certainly handle the air pressure for all but the highest outputs.
I’ve been a proponent of copper pipe for the DIY crowd, and I’d recommend it for institutional use as well, save for the cost.
One company has developed a line of plastic compressed air plumbing products, but it’s not recognized as suitable in many jurisdictions, and I, with a bit of background in plastics as well as compressed air, would want to be really convinced before I’d plumb compressed air through rigid plastic pipe.
Now there’s another alternative. It probably is a premium priced product, yet overall, with the ease of installation, maybe the installed cost is competitive?
Plumbing Compressed Air in the Garage or Workshop
I advise against using PVC (hard pipe) in plumbing compressed air…ever. Though the pressure ratings sometimes appear to be high enough, what’s not commonly known is that those pressure ratings drop very quickly as the ambient temperature increases. Also, PVC pipe under pressure can shatter if impacted, and bits of plastic shrapnel flying around won’t do anybody any good, and could do a great deal of damage.
So, when I saw a page about a garage compressed air plumbing system, my first thought was that the pipe looked like plastic. Whoops! Not good.
I took the time to examine their claims further, and learned that the pipe is coated aluminum.
I suspect, but don’t know, that this system will be quite expensive. However, if all your fingers are left thumbs, or you’ve got more money than you know what to do with, then maybe their solution is the way for you to go, to plumb your home compressor.
No one person can know it all, so if you can help folks plumbing an air compressor, it would be appreciated.
What To Use To Plumb An Air Compressor
If your air compressor is intended to be hard-piped into the workshop or plant, how do you decide what to use to plumb an air compressor?
First, let’s look at the choices available to us for plumbing the air compressor.
- plastic
- PVC hose
- rubber hose
- galvanized pipe
- black pipe
- aluminum
- copper
Plastic for compressed air
Be very careful when considering plastic for a compressor plumbing material. Not all plastic pipe (Schedule 40 or Schedule 80 PVC or CPVC for example) are able handle the pressure of a compressed air system. Make sure the plastic pipe is compressed air rated.
Polyethylene tube
For plumbing the workshop or small shop, sure, use poly tube. It’s cheap, flexible, water resistant, uses a host of relatively low cost fittings, cuts with a knife or tube cutter and is readily available.
First, make sure the tube you get is rated for compressed air. Some may not be. Typically that means a pressure burst strength about twice what the compressor can deliver.
Another concern is that unless you are really careful, poly tube fittings leak pretty easily. If you have a small bleeder leak in a fitting, and you shut down your compressor after use and drain the tank, the leak will be inconsequential. If you are trying to leave air in the lines overnight or for an extended period, the leak will drain the compressor tank, and your compressor will cycle on and off when you least expect it. Big leaks will affect the air flow to the tool, and must be corrected.
Tube size might be an issue since it’s limited in diameter. Run the main line around the garage or shop up on the wall, using 1/2″ tube as an air main. Lines tee’d off that down to quick couplers attached to the wall at strategic points would be 1/2″ too or maybe or 3/8″ depending on what is being powered by the air flow. The line to the tool would be rubber hose, sized to suit.
Water will collect in the lines, so if you don’t want it blowing through your air tools, get some compressed air filters in there.
PVC hose
This is plastic PVC too, but is built to handle the pressures a typical compressor might deliver. It is easy to install, fairly inexpensive, and is a good choice to plumb air from the compressor to a small workshop or plant.
There may be some concerns about flow capacity if your equipment needs lots of compressed air supply.
Install the PVC hose in the same manner you would the Poly tube referred to above.
Rubber Hose
Great for air lines to tools, wear resistant, stays flexible when it’s cool or cold, a good choice for air to the tools.
Also a fine choice to run an air main around the garage or workshop.
More expensive than some other options and just a bit more complex to plumb, yet lots of fittings around to plumb any way you want. Water resistant, crud resistant.
Install the same way you would the poly tube referred to above.
Galvanized Pipe?
Using galvanized pipe for a compressed air systems appears to be problematical.
Dozens of people have written in telling us about problems relating to the galvanized coating inside the pipe not being consistent, of it cracking, of particles being generated, about water from the now rusting the pipes etc.
Unless you are using some sort of quick connect system (which makes it a much more expensive option) galvanized pipe is difficult to install. Not a good choice.
Black Pipe
While black pipe won’t have a coating delaminate and contaminate your air stream, it sure does rust, and that rust may be come a problem over time.
Black pipe requires skills and equipment to install that the average person may not wish to acquire.
It’s plus is that it’s fairly cheap and it comes in large diameters which makes this piping the choice of a lot of plants that require high volumes of air.
Aluminum Pipe
There are a number of companies now that manufacture quick-assembly aluminum compressed air plumbing systems. They are wonderful! It’s just that this humble writer cannot afford to use them. If you can, go for it. They are neat, easy to install, and look very, very cool.
Use your browser and search for aluminum air pipe or air line and you will find suppliers.
Copper Pipe
Sure, a properly sweated copper fitting is leak proof, water and air-borne debris in the compressed air will not affect the copper, copper does not rust, it is available at any plumbing store, and it looks good.
Yet copper it is expensive, and for folks not into soldering copper, it’s complex to install. That is, of course, unless you used a quick connect system, and that rockets the cost up substantially.
Yet if the budget allowed, copper is what we would use for plumbing our air system, for sure, even with the issues of sweating copper fittings.
What To Use To Plumb An Air Compressor?
As with many choices, the best solution may be the most expensive.
For lowest cost, plastic is the first choice. Just make sure that it’s got the flow capabilities your compressed air equipment requires.
One solution to using multiple tools with one compressor and one air line, is to bring that air line to a manifold on your work bench.
A manifold is usually a block of machined aluminum, with an in-port on one or both ends for plumbing your supply line into, and multiple outlet ports along one or more sides into which you can install a coupler, or even just an instant fitting if you are using polyethylene tube to supply components on your bench with compressed air.
Other manifold styles are made of brass, or steel, depending on their manufacturer, design use and how many outlets are included.
Unused outlets can be plugged and reopened later if additional compressed air sources are required for your bench.
The in-port on the end of the manifold will normally be at least one size larger than the outlet ports, and sometimes larger, depending on the number of outlets.
In you install checked couplers into the distribution ports, then you can quickly attach any number of tools or compressed air components with mating connectors.
Things To Consider When Plumbing An Air Compressor
When plumbing compressed air from the air compressor to the application(s), here are some of the things to consider:
1) Size of the air line from the discharge port of the compressor
2) Type of air line (blackpipe, copper, polyethylene tubing, hose, other specialty piping material)
3) Type of fittings to be used.
4) To what will you plumb the air line? To a single coupler, multiple couplers, to an air manifold or a number of air manifolds?
5) How will you deal with the water that the air compressor will generate or, where will you put your air filters, and will you need ancillary compressed air drying?
6) Will drop lines be necessary and how will you drain them?
All of the above are predicated are how big the compressor is, how daily hours of run time, etc. More information on compressed air plumbing can be found here.
Does my air compressor leak?
Sometimes compressors will leak air from the receiver, back through the check valve, to atmosphere. Or there may be a pinhole leak in the receiver itself. In either case, it’s a waste of air and the energy used to compress it.
With your home compressor, simply disconnect the air line from the discharge line coupler and watch the gauge upstream from the coupler on the regulator. For an in-plant application, turn the valve off in the line from the compressor that feeds the plant and watch the tank gauge.
If the pressure falls, you’ve got a leak somewhere in your compressor head or tank, and air is bleeding out of the receiver to atmosphere through that leak. The faster the pressure drops, the more money you’re wasting compressing air that’s never going to be used.
Unloader Valve Hissing
Question:
Porter Cable 5hp., 60 gallons.
The unloader valve hisses air while the compressor builds pressure, then when cutoff pressure hits, it unloads, and the leakage stops.
I really haven’t noticed this before. Is this normal?
We answer…
Howdy;
In a word, no.
Your unloader valve should be closed when the compressor is running, allowing all of the air being compressed to be sent down to the tank, and not bled out of the unloader valve.
When the compressor reaches the high pressure cut-out, the pressure switch reacts to that high pressure point, shuts off power to the motor, and then opens the unloader valve to unload the compressed air trapped over the piston.
It does this to help the compressor start more easily next time the low pressure trips the pressure switch to start the motor. If there was air trapped over the piston, the motor would have to work a lot harder to start against that load.
In your case, it sounds as though you have a seal leak of some kind in the unloader valve.