1227749

[Rudi Machilek]

<Original Message>
Oh, and I pressure tested my homemade fuel rails this morning and they
leak right through the aluminum tubing.  I found that odd.  I know
aluminum is somewhat porous compared to other metals, but 100psi of air
pressure on the end of the fuel rail, submerging it into a litter box
full of water resulted in small bubbles forming on the surface of the
aluminum.  When the pressure is released, the bubbles appear to receed
back into the aluminum.  Very odd.  Just thought you'd all get a kick
out of it.

<Reply>

Seamed tubing, aluminum, or stainless even, may show bubbles when tested with nitrogen (air).  If the bubbles do not flow, no real big deal.  Any liquid fuel is a lot bigger molecule than nitrogen.  Use seamless tubing to avoid that.  

For fun, take some 304 or 316 SS tubing (even seamless) and submerge it in Clorox for a week.  Now leak test that.  Provides a new definition for porous.  Use 317 SS (not very available) and almost no effect.  Materials studies are a great way to burn a bunch of hours.  

Rudi Machilek