When replacing an air-hose fitting with a barbed brass fitting, the usual process is to seal the connection with a small hose clamp. I use my plumbing tools to make a cleaner connection on my 1/2-in. O.D. air hose.
As shown in the drawing at right, I cut the end of the hose square. Then I slide a 1/2-in. PEX plumbing crimp ring onto the hose so that 1/8 in. of the hose extends beyond the ring. Then I apply some light oil (you also could use Vaseline) to the barbed end of the fitting to facilitate insertion. Finally, I compress the ring with a set of crimpers.
R. Timothy Maddox, Lynchburg, VA
Edited and Illustrated by Charles Miller
From Fine Homebuilding #226