Friday, December 1, 2006

AV - Flying On The Cheap -- Hose Fittings

A fellow homebuilder spotted a female air-hose quick-connect fitting on a fuel I'd just finished sloshing (riveted aluminum tank) and told me he hadn't bothered to pressure-test his tank since it was gravity feed and he figured just filling it up was enough of a test. He went on to say that it hadn't leaked so I guess he was right.

I didn't bother to tell him the fitting wasn't there for the purpose of pressure-testing.

Heat the end of your 2-ply fuel line in oil, you can push it onto an air-hose quick-connect fitting. Safety wire or even a hose-clamp for the rich bastards, you got yourself a fuel-line fitting.

Why? Because it costs less than half a buck and works perfectly well. Gettem from Harbor Freight. Two male fittings, one female and a quick-connect coupler. Wait for the sale, you can pick up the kit for $1.39 (otherwise, it's about $3).

No big deal? Maybe not, if you got lots of money to waste.

Personally, I prefer aluminum tubing for fuel, vent & vacuum lines. Old habits, etc. But if you have to squeeze ever nickle until the buffalo farts, hose is makes pretty good sense. When properly installed & supported, frequently inspected and periodically replaced, hose can be made to serve for the plumbing in a minimum-cost, VW-powered puddle jumper. Assuming you've got a drawer full of fittings.

Back around Thanksgiving I reached in the drawer and came up empty and the local auto-parts place wanted something like three bucks for one 1/4"-NPT to hose fitting, I needed four of them and they only had the one in stock. I could turn them up on the lathe faster than they could order them but on the way home I stopped by the Harbor Freight store in Escondido and they had a whole bin of air-hose fittings on sale. Bought a bunch. Worked fine.

They're cast brass rather than extruded. And only come in straights, male or female. But a gravity-feed system doesn't see any pressure to speak of and space isn't at a premium in this particular airframe so straight works okay.

Yeah, it's outside the box. No, it isn't unsafe; not when properly installed. And the proof is no farther away than testing it for yourself.


1 comment:

flybynightkarmarepair said...

Could you elaborate on the use of safety wire instead of hose clamps?

I fear cutting through the hose, but I guess it's hard to get the wire that tight with the twisters before it snaps.

Here's how another cheapskate does it.