It seems a lot of folks need help plumbing compressed air. At least, that topic surfaces almost every day in questions folks send in to this website.

So much so that I have created a forum page specifically about that plumbing compressed, a topic that seems to be of interest to many DIY (Do It Your self person) and the industrial plant-air mechanic.

First, a few fundamentals about compressed air are in order.

Plumbing Compressed Air Fundamentals

Compressing air generates water. The larger the compressor and the more frequently it runs, the more water will be generated. There is lots of information about compressor generated water on this web sites o I will not go into it further on this page.

Since there are not too many air applications where water spraying out along with the compressed air is a good thing, you will need to attack the water problem at the source. That is part of good plumbing of compressed air.

Air hose - depending on the application, air hose can be a viable method of plumbing compressed air

Depending on the end application, air hose can be a viable method of plumbing compressed air

Plumbing In A Compressed Air Filter

An important water removal device is the compressed air filter. Free water generated by compressing of air is a problem. installing compressed air filters in a number of locations throughout the plant will remove free water from the air lines.

If you do not have a filter installed upstream from the air regulator on your home compressor, and if you are using your compressor for longer than a couple of minutes at a stretch I recommend you install a compressed air filter right before the air regulator on the discharge line from your compressor.

There are complete details on compressed air filters linked from the sitemap page.

Plumbing An Air Regulator

The big box store compressors usually come equipped with a regulator. It is installed upstream from the discharge coupling on the compressor.

This regulator controls the air pressure level flowing to your tools or other compressed air using applications. You set the regulator to the downstream air pressure your equipment needs.

You want to dial down the air pressure coming from your compressor to the lowest pressure setting at which your air tools will work properly. This saves compressor cycling, energy, and extends the life of your air driven equipment.

Dialing down the air pressure close to the equipment minimum operating pressure applies to both DIY home compressor users, and industrial compressed air applications.

Read complete information on air regulators on the page on this site, or, if a DIY’er, you might consider getting my eBook on the compressed air regulator available by clicking the link in the navigation column.

That is enough for fundamentals. Now we will get to the plumbing compressed air information. I have broken the plumbing of compressed air into sections; portable and industrial installations.

Plumbing Portable Compressors

The fact that an air compressor is portable removes the need for installing it in one place permanently, and that normally leaves out hard pipe plumbing. That is typical, though I have seen some pretty fine portable compressor installations that have been hard piped into the garage or workshop.

Often DIY portable air compressors come with a sort of plumbing kit, including package of connectors, couplers, maybe a blow gun, an air chuck for filling tires, and often a PVC hose.

The PVC hoses included are hard, and get really harder when it is cold, making them somewhat difficult to use.

The included fittings are of suspect quality as well. All in all I was not very happy with using the install kit that came with all of my home-workshop compressors.

I finally broke down and got rid of the low cost PVC hose that came with my small portable shop compressor, and sprung for a rubber hose. It has much greater flexibility. If you find the PVC hose that came with your air compressor hard to work with, consider doing the same. You will be glad you did in terms of easier use of compressed air.

The Basic Compressor Plumbing

Depending on what how you use your home portable compressor, all you really have to do is plug the power cord into the wall socket.

The air compressor will have a discharge coupler downstream from the regulator. You plug the connector on your air hose into that coupler to get air flowing into the air line and insert your air tool into the coupler at the other end of the air hose. Simple as that!

Yet some folks find that when they do plug in the air connector, they do not get air in the hose. There’s a page on this site where you find the solution to the no-air-out-of-hose situation linked from the troubleshooting page.

Air Tool Lubricator

If you use air tools, they will need regular lubrication.

Rather than a continuous tool lubricator, when I start to use a particular air tool, I put three drops of air tool lube oil into the in air-port of the tool before use.

Then, after using that tool, just before I put the tool away, I put three more drops into it and give it a 1/2 second blast of air to distribute the oil. That’s all the lube I use, and my tools stand up well.

Mind you, I only use them for a couple of minutes, put them down, do something else, and then use them again for a couple of minutes. It is not continuous use at all. If you are using your air tools constantly, you may want to consider an in line oiler. There is lots of information on air line lubricators found on this site.

While hard-piping of an industrial air compressor is normal, some folks opt to have a portable compressor able to be connected to fixed plumbing in the shop, and then use the portable plumbing when they have moved the compressor elsewhere.

The concepts for both heavy duty industrial compressor and home shop compressor plumbing are essentially the same. It is the cost that will vary substantially as industrial compressed air plumbing is more complex, parts are larger, and as a result are far more expensive.
What Pipe When Plumbing Compressor

It occurred to me that, so far, I have not talked about what air pipe to use when plumbing compressed air runs.

If you want to read about it now here is in-depth information on compressed air piping materials.

Fixed Compressor Installation

Filter First: First off, you will want a general purpose filter installed at the discharge of the compressor. That filter port size must be either the same pipe size as the discharge line, or bigger. If the filter is installed right at the outlet for a large compressor air tank, for example, using a filter with a smaller port size may result in inadvertent restriction of the air flow from the compressor tank to your plant air mains.

What compressed air filters do and how they operate can be found here. There is not much point in rewriting all the info and adding it to this page. Go to the filters section first, if you are not sure about them, please.

Air Regulators Next: While small portable air compressors come with a regulator installed on the compressor discharge as a norm, there is generally no need to install one on the discharge from a larger, fixed installation compressor discharge unless the air is going to just one station. Then using the regulator on the discharge from the compressor tank to reduce the output pressure to the sole air use station makes sense.

I am a strong proponent of throttling down air pressure at the point of use to the minimum air pressure necessary for the air tool. This will reduce compressed air use and wear and tear on both the air compressor and air tool.

Install an air regulator at every point-of-use in the shop. Adjust the pressure to the optimal setting for that piece of equipment. This will help reduce air waste and save money.

After Cooler:

High consumption of air means higher air temperature entering the plant mains. That typically means more water will end up in the air mains.

In the drawing I show the compressed air passing through a compressed air cooler, an after-cooler, a type of which you will likely need to dewater the compressed air if your plant is consuming a lot of compressed air for manufacturing etc.

aftercooler installation

If you are plumbing compressed air from the compressor for plant use, plumbing the air from the tank to the ceiling mains in a similar fashion to what is shown in the sketch above will provide benefit and help dry plant air.

If it is a home shop you are plumbing air for and you want a hard-plumbed-station into which you can plug the air from your portable air compressor, then this is the right way to plumb that station too, particularly if you are going to be using the compressor in the fixed-installation a lot.

You have now plumbed properly from the compressor discharge or from the air tank, through to the air filter, perhaps through cooler or drier, and then to a Tee.

Note the drop leg drain

Below the Tee in the drawing above there is a section of drop line, at the end of which is a drain, shown in the drawing. This could be a manual drain, or an automatic float drain. If you use an lot of air, I recommend that this be an auto drain, so maintenance does not have to worry about remembering to drain it regularly.

Now you want to make the connection from the riser air pipe into the ceiling air mains.

Compressor Plumbing At The Ceiling:

plumbing compressed air from the ceiling mainsThe line that goes up to the ceiling, whether supplying air up to the main, or bringing air from the main back down to an application, loops over the pipe and connects where shown in the photo.

Drop Lines: Good compressed air plumbing practices will help prevent water that has condensed out in the mains from flowing down to the equipment via the drop lines from the overhead air mains.

Any water that is in the air line already will tend to stay in the riser, dripping down to the auto drain at the bottom. Any water that condenses in the air main, will tend to stay in the main, rather than following the air drops down to the air using equipment. Installed this way the water can flow along the air mains to a drop leg with an auto drain.

As the drawing depicts, take the drop line from the top of the air mains. Any water that has condensed in the mains will flow along the bottom of the air pipe, not at the top. Gravity works!

I recommend too that you install an auto drain at the bottom of the drop line, and Tee up a foot or so from that, for a feed from the drop line over to the air-using equipment.

If your equipment is using a high volume of compressed air, then air flowing down the drop to that equipment can still allow water vapor to condense out. Taking the equipment feed up from the bottom of the drop line helps condensate to flow by the equipment feed to the bottom of the drop leg. There it will be drained off periodically by the auto drain. If you opt for a manual drain for this drop leg, make sure it gets drained regularly. If the pipe fills up to the Tee, you’ll have lots of water flowing over to your equipment!

For the home workshop?

Do you plumb this way for your home workshop? Entirely up to yourself and the amount of air you expect to be using and the expense involved. If your air use is measured in hours rather than minutes, it is probably a good idea to install your air supply lines properly.

Compressed air manifolds

Consider plumbing the drop line into an air manifold.

A manifold will allow you to feed a supply of air at a certain pressure into the manifold, and then, via a series of smaller air ports along the side of the manifold, plumb air to a number of different pieces of equipment.

 

Air manifold - plumbing compressed air

Small compressed air manifold

The addition of a regulator at each of the outlets would allow for reducing the pressure from that outlet to a specific air tool or use, if desired.

Some Point Of Use Air Components

You will need to add an air filter where you are using the air, as well.

The greater the demand of air for that equipment, the higher the water condensate volume will be, and filtering the air just before it enters the application will remove any free water before it can get into your tools or equipment.

Downstream from the filter you will want to add an air regulator so that you can reduce the pressure to the minimum necessary to do the work at this location. This reduces your operating cost, and at the same time, reduces or eliminates (depending on where the pressure is set) the pulses in the compressed air supply created by the air compressor kicking on and off.

If the air tool (perhaps a paint gun) really requires very dry air, consider installing an in-line air dryer where that level of dryness is needed.

Depending on the air tool or application, it may need a lubricator as well.

My suggestion is that if you do not need a lubricator, do not start using one. Oil from the air line lubricator tends to flush out any factory lubrication in the equipment, and then, you will have to lubricate that piece of equipment from then on.

I hope the preceding page about plumbing compressed air have been useful. As always, if you have any question, please just ask.


Information that might help:

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Compressed air manifolds

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I have two buildings that are about 300 feet apart. I am trying to figure out

PVC pipe swelling and bursting

The 15 hp compressor feeds a small plant. An industrial hose of about 6 ft connects to PVC pipe from that point.


New comment? New question? Please add it here along with photos to help others help you with your compressor and equipment problem!