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