Teflon-lined Fuel lines?

[GS guy]

That's an idea Pile.
I could "hold" the hose by P-clamping it down to a board. Maybe with padding (wadded up towels) located to catch any flying fittings. A remote ball valve could apply the pressure, keeping the operator some distance from the hose.
These hoses are rated to 250psi. Figure I'd test to my air compressor max, about 130psi.

[Piledriver]

That's an idea Pile.
I could "hold" the hose by P-clamping it down to a board. Maybe with padding (wadded up towels) located to catch any flying fittings. A remote ball valve could apply the pressure, keeping the operator some distance from the hose.
These hoses are rated to 250psi. Figure I'd test to my air compressor max, about 130psi.

You still need to do a final test with a fire extinguisher handy, the 044 dead headed, this in case the regulator orifice gets plugged (has happened)
With the engine running/alternator power it potentially could see 180+.
Noteyu cannot pinch off teflon line, it crimps it and leaves a weak spot.
You'll have to use a bit of high pressure rubber EFI line to do the test or add a valve temporarily.
Shop rags and zip ties are pretty strong esp doubled up.
Hydraulic fails are far less spectacular that compressed air fails, just make more mess.
(very little stored energy in an incompressible liquid)

That for example is why things are hydroformed vs using high pressure gas...
Compressed air can be far more dangerous when things let go.
With liquid (even gasoline) when it lets go spectacularly it... pees a little and the pressures gone.
(if the pump gets shut off, anyway, an 044 can totally move some fuel if you let it)

[GS guy]

Thinking about your last post Pile - trying to figure how I could safely develop around 200psi to "thoroughly" check the hoses. My compressor only runs up to about 125-130psi, so not enough. I made up a test manifold from some extra fittings, with a quick disconnect inlet, shut-off valve, T for fitting a gauge and AN adapter.

The only way I've been able to figure out how to develop that pressure (besides your "in-situ" suggestion) would be to fit a higher-pressure outlet regulator on my C25 gas bottle. I searched some regulators that should work with the CGA 580 inlet fitting, typically used for AC work. I found several that can go much higher output than needed (300psi should be plenty), and as low as around $50. I'd probably fit a hard line on the regulator to the manifold - not sure an air hose would be good for 200psi? Have to think about securing the hose being tested so if an end blows off it doesn't hurt anything!
Jeff

[Piledriver]

Most air lines are rated to 300 PSI max.
AC lines and related bits are 3K PSI, 800PSI working range...
I have used my AC gauges etc for ...odd things, as SAE flare is easy to adapt to anything, and they are reasonably prescise and appear to be accurate (JB Zeppelin)

The full AC service setup worked fabulous for evacuating my shocks for a proper degassed oil fill, and later pressurizing. I even added an extra fitting on the ex-KYB external reservoirs so this is trivial.
It was done with the shock all assembled with the spring on and could be done in the car.

[helowrench]

This brings up a question: How do you pressure-check your made-up hoses?

Sure, easy enough to fit a plug at one end, and modified fitting at the other to connect with an air hose. But how do you "constrain" the hose if one end were to blow off? Check it from a distance with an air flow valve? If one of the fittings were to pop off at 100+psi, it's gonna hurt whatever it hits!

Once upon a time I managed a hydraulic shop.
Some of the components we tested were up to 30K PSI.

They got tested in a 3/8" hot rolled steel enclosure.
Any lines we made in house got pressure tested in a 1/8" hot rolled steel box with a 1/2" lexan lid. (6K PSI)

For something like this you would pressure test at 2X the max pressure, so 300ish.
since there are no components with appreciable mass, you could do it under a spare rim, behind a wall, etc.

Rob

[helowrench]

Thinking about your last post Pile - trying to figure how I could safely develop around 200psi to "thoroughly" check the hoses. My compressor only runs up to about 125-130psi, so not enough. I made up a test manifold from some extra fittings, with a quick disconnect inlet, shut-off valve, T for fitting a gauge and AN adapter.

The only way I've been able to figure out how to develop that pressure (besides your "in-situ" suggestion) would be to fit a higher-pressure outlet regulator on my C25 gas bottle. I searched some regulators that should work with the CGA 580 inlet fitting, typically used for AC work. I found several that can go much higher output than needed (300psi should be plenty), and as low as around $50. I'd probably fit a hard line on the regulator to the manifold - not sure an air hose would be good for 200psi? Have to think about securing the hose being tested so if an end blows off it doesn't hurt anything!
Jeff

A small 12v tire compressor would put a nice pressure behind a hose filled with water, and many are rated to 300psi

Rob

[dragvw2180]

Slide your hose inside a piece of pipe/tubing , if it comes apart it will be unlikely to harm you .

[raygreenwood]

For the record...responding to the original post.....the modern nylon tubing fuel lines have "0" issues with the "witches brew" of gasoline and ethanol or even methanol from 10% to E85.

Also while I see the niftyness of teflon.....costs aside ....it has lousey impact resistance and bend radius. Some of the worst for any thermoplastic. Same issues with teflon brake lines. You cannot slew ot around much, bend it much or let it flap around unsupported or its prone to cracking.

Ray

[Clonebug]

Seems like a lot of worrying for a non issue I feel.

I have been running EFI rubber fuel line for 4 yrs now and just using FI clamps to hold it on steel fuel line.
I do check it every winter when I have the body off but there has been zero issues for me. Mario has done the same for even longer without issues.
I do keep the hose runs short and slide the hose at least an inch if not two inches onto the metal line. Most times when I have to pull them apart in the winter I can hardly separate the hose from the steel and almost have to use a pliers to twist it loose.

[GS guy]

Ray - this system is a little different than the typical standard teflon tube type - the hose is made with a conductive type of teflon and molded in a helical shape. This eliminates internal static build-up (which the hose ends or outer SS braided covering do not), plus makes it much more flexible than traditional solid wall tubing. It has an outer reinforcement layer of fiberglass somehow molded to the hose OD, then covered by a tough outer synthetic braid. The ferrule "screws" onto the hose helix and secures it to the end fitting. Here's a pic of a short section of hose (with teflon taped wrapped around the ends to prevent outer braid unraveling), a section with the braid removed showing the brown-ish fiberglass layer (note the spent ferrule on one end, one I had to re-do), and an end-on view.



Here's my test rig with one of the shorter hoses attached:



Clone - since I had already plumbed about 90% of my fuel system with AN hosess, I was primarily concerned with my choice of Aeroquip conventional hose, as I couldn't find any supporting documentation on how well it stands up fuel over the long term. Earls has another pretty neat (and less $$$) system based on a new "barrier" hose formulation with slip-on "AN" fittings. These use standard EFI hose clamps or compression clamps to secure the hose, but utilize an AN connection. I suppose you could use an standard hose with these since they fit standard hose IDs (like Gates barrier hose). Limited fitting types though, I think straight, 90 and 45 only. Also, JEGs has a similar slip-on AN fitting, in straight only but very inexpensive. All overkill? AN stuff for sure! In my case, more a matter of "want" vs. "need".
Jeff

[GS guy]

I'm re-thinking my testing apparatus. High pressure gas and metal end fittings require some serious thinking about safety, unless I was wanting to make an "idiot failure" youtube video!

Read a post of someone using a hydraulic porta-power hand pump to pressurize their hoses. Seemed like a slick idea, especially when I found you can get a 10T hand pump for less than $50 on Amazon! That's about the same as I was going to spend on the regulator, so the cost is a wash. Easily exceeds any hose psi requirements. Just need to get a hyd QD for the test rig and plug it together. Probably test inside a couple of heavy cardboard boxes - avoiding some of the mess if one should blow. Clean-up could be a PITA, hoses would have to be flushed and getting any oil out of the outer hose covering would be a pain. I read you can just release the pressure and let the oil drain back into the pump. Purging the air out will be the tricky part, without getting oil all over the place.

A plus is I'm not going through my welding shield gas to check the hoses. Seems like a win-win.

[Piledriver]

Purging the air out will be the tricky part, without getting oil all over the place.

Do any auto AC work? Want to?
When I wanted to fill up my new Bilstein 36mm DIY reservoir shocks with oil,(Put some old KYBs to good use as resis) I sucked all the air out with my vacuum pump/gauge set and under-vacuum/pressure valve stem tool, and allowed it to suck the oil in. I repeated that a couple times and let it run for awhile to vacuum degas the shock oil.
(details left out due to unrelated to this thread, but the gas area was also under vacuum so the floating piston location was set with a simple pvc spacer, taken out right before pressurizing)
To pull that off required an extra schrader on the resi in the fluid end, and an additional 1/4" ball valve.
(I used high pressure 1/4" SAE flares/fittings for everything)

All this was done with the shocks/springs assembled, and could probably be done installed.

This was all done at the kitchen table. There was not a loose drop of oil to be found.