ORIGINAL: Harley Condra
As I mentioned before, and before, there is a "funnel shaped ramp" inside the fitting that the hose must fit, in order to create the seal. It will not seal on brass or aluminum, as the material must "form fit" itself into the seal area to create the seal. The elastic properties of polyurethane and other formulations of plastic hose/tubing is what allows this "conformal seal" to be accomplished. A flexible ring of fingers with action similar to a "Belleville Washer" retains the tubing by spring pressure. Depressing the blue colored collar flexes the spring loaded fingers and disengages them from the surface of the hose/tubing, allowing extraction.
Brass and/or aluminum tubing is not malleable enough to be formed into the required shape with just finger pressure.
Harley Condra
BVM REP
JetCat REP
Harley,
I have never disected a Festo fitting... so I don't know about the "funnel shaped ramp". I don't even use Festo, I use Legris fittings, which funtion the same, but I can get them at the local industrial supply store.
What I do know is that I have both inserted hard plastic tubes (3mm antenna guides from the LHS) and brass tubes into these fittings... and they seal.
And like said before, even Jetcat uses a Festo fitting on a brass tube... just look under the intake cover of your engine.
Now, I'm not saying inserting something into these fittings that doesn't "belong" there is the way to go. All I'm saying is that it works for me apparently.
Hmmm, perhaps the brass only works because I use a tubing cutter? Now you've got me wondering about that.