Air Hose

Compressed air hose isn't much good without the fittings to attach it. So, I've got lots information on this website about air fittings too.

Since I had the air fittings page already built, I thought it might be useful to you to provide information about the compressed air lines themselves. After all, it's the air line that brings the compressed air through the fitting into the air tool, air valve, air cylinder or other air application.

When it comes to connecting parts of your air system or circuit together, along with the appropriate fittings, you have the choice of using Air Hose or air tube, which is located here.

Hose Size

When you are trying to figure out what hose size you need, or even just how a 3/4" hose is well over an inch in diameter, just remember the acronym H.I.D...

The 'H' in H.I.D. stands for HOSE. The 'I.D." in HID stands for the hose "inner diameter".

Hose size is measured by its inner diameter.

A 3/8" hose will have a hole in the center that is exactly 3/8" in diameter.

Will all same size hoses have the same outer diameter (O.D.)? Nope, they won't.

Different manufacturers offer air hose with varying wall thickness. Therefore, one 3/8" hose might be just under 1" in outer diameter, another might be a 1 1/4" outer diameter, yet in both cases the I.D. will still be 3/8", identifying this one as a 3/8" hose.

It is often the higher priced hose that has a larger O.D. due to that manufacturer using more mass in the wall thickness or integrating reinforcement nto the hose wall for greater burst strength.

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Hose or Tube?

Be a bit careful when speaking with folks about air line hose.

First, make sure they are talking about hose and not tubing, then you have to clarify where the dimension they gave you came from.

Often, the technician will give you a hose dimension as 5/8" or 3/4", but they may be talking about the hose O.D. If you size the necessary fittings based on that information, they won't work, and you'll be making another trip to the tool crib or the industrial distributor for correct ones.

You need to know the air hose I.D. to get fittings that are sized correctly.

Hose Types

When you buy a low cost DIY type compressor, it will often come bundled with a low cost, lower quality PVC air hose.

In the photo left, the hose separated from the connector within moments of me adding air to the line.

And, PVC hose gets hard when the weather cools. So it's quite difficult to handle when it's cooler out in the workshop.

It were me, even though it's higher cost, I'd go with a decent quality rubber hose, similar to the one in the photo at right.

A rubber hose is flexible in all weather, and is abrasion resistant. Air hoses often get trod on or have things like fork trucks running over them. Do yourself a favor. Buy a better quality hose if you want it to stand up to this abuse.

Complete With Fittings?

Unless you are buying a bulk hose off a reel, typically your air hose will come complete with male NPT fittings on both ends of the hose.

To use the hose, you will add a connector to the thread on one end, and a coupler to the thread on the other. This creates an "air extension cord" which can be used to bring air to an air tool from the compressor discharge coupler.

If you have two or more air hoses with couplers and connectors installed on them, you can connect one hose to the other, extending your air hose length almost indefinitely.

Pressure Drop

Air pressure drop through a long hose cannot harm an air tool. Power drop through a too long electrical extension cord can harm an electric motor. It's always better to plumb a long air line to where you need the air, than to run a long extension cord to the portable compressor.

Pressure drop is a concern for your air driven equipment. It might be worth your time to have a review of how pressure drop affects your air tool use.

Barbed Fittings

Hose fittings will usually be a barbed style on one side and a "quick connect" device, also known as a "coupler - connector" on the other side.

The barb will be a specific fractional size, and that is the size that will correspond to the I.D. of the hose.

The barbed fitting fits a certain range of hose I.D.'s. So you would purchase a 3/8" barb to fit inside the I.D. of a 3/8" hose.

First you slide a gear clamp over the hose, then insert the fitting barb into the hose I.D. Some folks use a little soap to make this easier. If I find that the barb is tight, generally I just use some good 'ol spit!

Once the barb is inside the hose, slide the gear clamp back up the hose until it's well over the barb on the fitting and tighten securely.

On the other end of the barb could be, as noted, any number of fitting configurations, depending on what it is you want the hose to connect to.

Though they both are used to transport compressed air, air hose is not the same as compressed air tubing.