Why aluminum fuel lines?

[bret]

Ok, take a deep breath, this is JUST a question....and involves gasoline so don?t flame me too hard. So, I have been doing a non scientific test of using Parker 293 air brake line for transporting gasoline from my portable 32 gallon plastic fuel cell to my 160 gallon boat fuel tank for 12 years, I am using a Mallory 240 GMP pump. (This is easier to fill the boat than draging it into a station) over the years I have pumped thousands of gallons through this same 20 Ft. line. Dragged on the concrete, sitting in the sun for years, and no problems what so ever. It is rated at 500 PSI working pressure and temps from -58 to 302 F. I know it is designed for air, but they know it is also going to be used around lots of petroleum products on big rigs. This one little plastic line is indirectly stopping 80,000 + Lbs trucks on our highways every day. SO?.what would be the concerns of using this line BEHIND the firewall, from tanks to selector valve and up to firewall, I know there would be a concern if flames were on the firewall, so maybe not there? Just throwing it out there, what do you think, no cracked or leaking aluminum flares, easy to install?..

[David-aviator]

The airplane is experimental, you can use any fuel line material you wish. It is your airplane and you will be flying it.

If you are looking for someone to give the idea a blessing, that probably won't be forth coming due to liability concerns.

Beyond that, anything non-standard in these machines affects its value. If you decide to sell you'd have to convince the buyer that truck air hose is better than what the plan calls for - or remove it and install aluminum.

[TS Flightlines]

Bret, many late model cars and trucks use a nylon hose crimped to rigid tube for fuel. At the pressures we run, its not a big deal. A teflon hose is essentally a 'plastic/nylon' tube that is thin walled, and similar to the nylon you are using. Teflon gets its superior working pressure from the reinforcement braid.

Yeah you could use if you wanted to, but I think the DAR's and A&P/IA's on this site would have a problem with it. It's not consistent with aircraft materials.
My .02 worth.

[BillL]

Bret,

One thing that you should be aware of is static electricity build up. Just flowing fuel through a plastic hose can build up a static charge in the fuel and while the amps are low, the voltages can be 50,000 volts easily with high velocities. This is the reason that teflon hose for aircraft is carbon impregnated and has a conductivity specification.

Typically automotive does not flow fuel that fast, but on a big yellow machine recently there was a non-metallic hose that kept weeping, it was from arcing to grounds. A test at SwRI showed at the diesel fuel velocity that line could build up 30k volts in 6 inches of flow distance.

I can not quote the science, but it is like any other static buildup. You are probably lucky in your boat if it is a primary fuel supply line with high flow rates. It may not be passing a grounded part or the velocity is low enough not to cause a problem.

Here is one article on it: ttp://people.clarkson.edu/~wwilcox/Design/flamliq.pdf

Yes, you can use any fuel line/ hose you like, but be aware of this phenomenon. I think about this as one of the reasons for grounding AC when fueling too.

[TS Flightlines]

Great comment Bill. Even non conductive teflon will develop some static charge. Any of the 'older guys' remember the water sprinkler hoses ( thats what they used to call braided teflon with out the conductive liner). Its pretty self-explanatory!
Tom

[az_gila]

Originally Posted by TS Flightlines

Great comment Bill. Even non conductive teflon will develop some static charge. Any of the 'older guys' remember the water sprinkler hoses ( thats what they used to call braided teflon with out the conductive liner). Its pretty self-explanatory!
Tom

Which is exactly why you want aircraft stuff.

The Aeroquip Teflon hose is conductive -

http://www.aircraftspruce.com/catalo...eroquip666.php

[RVDan]

The Aeroquip 666 hose (the teflon lined type) has a conductive inner liner that is carbon impregnated to make it conductive. The conductive film was added about 20 years ago due to leaking lines created by static discharges through the teflon to the stainless braid.

I do have to say that most lines made from non-conductive materials that are intended.

[bird]

From an electricians standpoint,for the last 30 yrs or so, static electricity is dangerous. Flowing liquids can cause very high electrical potential as indicated above. Proper grounding/cathodic protection is essential. It is not always a problem because of the particular system installation, and conditions.

Bird

[PerfTech]

... I have this hose and fittings in stock at all times, so one day I needed to replace the fuel line on one of our shop forklifts. I thought what could go wrong? I grabbed some HP airline, fittings and made a line up. Looked great but rotted out the inner rubber and began to leak, seep and got hard so if you bend it, it cracked inside and began to leak even more. I learned and wouldn't use it on fuel, gasoline or propane. Allan...

[TS Flightlines]

All hose liners are NOT the same. Even in industrial applications, manufacturers make their liner to 'conform' to a set of specs, usually, SAE or DIN. BUT the liner material 'may or may not' be compatible for your intended application. Knowing the manufacturer and their products is a huge help. Dont just guess that because you are using it for one application, whether correct or not, its ok for its use in something completely different.
If youre going to use a teflon hose in aircraft for fluid flow, use a conductive liner.
Tom