[lust4speed]

Getting ready to replace some aging push-lock neoprene lined hose since it is showing its age. Going with the PTFE lined hose and the major brands are pushing the carbonized Teflon liner saying that sparking from the fuel to the stainless outer braid can degrade the PTFE liner where it will fail prematurely. The added carbon maintains a ground so no sparking. Sounds necessary but then see that there is a lot of PTFE hose offered for use with gas that is not carbonized. Is it a good thing to ante up for the more expensive hose or is it a marketing ploy?

[Bill Eveland]

Not sure about the carbonized part, but ive heard good things about this hose on amazon, they sell it with fitting kits also. Much more reasonable price than the big brands.
https://www.amazon.com/EVIL-ENERGY-S...s%2C154&sr=8-3

[Shiny]

I'm lost on the physics with this one.

Does flowing gas inside the tubing generate enough static charge to break down the ptfe insulation (tribo-charge)?

If so, yikes.

I'm curious as I dealt with a similar problem in my previous life. It was weird. We had a high-speed motor that used precision metallic bushings. The motor ran at high rpm and the bearings were designed to use a well-controlled oil film that insulated the shaft from the bushing. The charge would build up, break down the oil film, and the discharge event would mess up some electronics in the system.

The difference was high rpm in that application vs relatively slow-moving gas. Is the gas velocity high enough in an automotive fuel line to cause this or are there other applications with higher fluid flow that need the conductive PTFE?

[lust4speed]

Here are three that offer PTFE hose with carbon added:

Aeromotive: "These liners are specially carbonized for conductivity, which is critical for fuel handling."

Fragola: "Hose sizes 6-12 AN have a conductive core to dissipate static electricity."

Earls: "PTFE inner liner impervious to all known fuels, oils, and coolants used in automotive applications, is carbon-infused for static dissipation, and has ultra-low coefficient of friction to promote maximum flow."

Other problem I'm finding is no manufacturer adheres to the original AN sizing guidelines and inner and outer diameter are all over the map. Pretty well forces me to order a companies fittings along with their hose. Hose sizes for -8AN run .41" to .49" while the original AN guidelines you simply put the size over 16. So -8AN would be 8/16 which would reduce down to a 1/2" or .5". Doesn't seem line any company supports that now.

I had found Evil Energy's listings on Amazon and prices are great... but caution is pulling me to order the Fragola hose and fittings since this should be a one time purchase. Would hate to order the cheaper hose and have to replace it in a couple of years due to pin holes.

I put the carbonized PTFE hose in a friends strip/street car. A few months later he physically hurt the short length of hose from tank to electric pump and replaced it with some Amazon hose. It's been about 6 months and he hasn't blown up yet.

[Shiny]

I always learn a lot on this forum... thank you.

I'm curious if new cars use PTFE-lined fuel lines and if so, are they conductive? Is this only an aftermarket question?

The risk is real but how probable? Failure by static discharge may be improbable, but the consequences of a failure may justify the cost for you.

I'm certainly aware of explosion risk from static discharge (gas cans, tanker trucks, gas pumps, etc.) but I never thought about PTFE-lined hose leakage from static discharge damage being a significant issue in cars.

When we assessed risk for new product designs with hundreds of parts and ways to fail, we'd rank them using a simple formula (RPN). Risk Factor = probability of occurrence x consequences x ease of detection. If the consequences carried safety liability or regulatory failure, the design had to be changed and the cost to change was accepted.

[Jack Gifford]

I can't picture a spark igniting liguid fuel.
Question- has PTFE-lined braided hose gotten any more flexible than when it was first around?

[Half-Inch Stud]

Fuel gauge ought to have sparks during slosh yet the rich (even wet) mixture keep us calm.

Fuel building static charge in a Teflon line, if so, how high?, and the carb ought to be the discharge anode. What is the line exterior made of?

Is fuel mildly conductive? If so then then leakage current ought keep the charge low. I suspect the fuel is much closer to insulative, like clean water.

[Shiny]

As I understand, failure mode is leakage due to arcing from ID to OD (fuel/PTFE interface to stainless jacket) causing breakdown of the PTFE. It would take VERY high voltage to break down PTFE. Agree conductivity of the fuel inside is a key question... gas vs ethanol and all mixtures in between ??

Here's a photo of a damage site I found online:

http://www.microlabgallery.com/galle...2040X%202.aspx

Hard for me to believe this is a common occurrence and fuel leaks don't always end in violent explosions but the risk is there I guess.

[lust4speed]

Originally Posted by Shiny

As I understand, failure mode is leakage due to arcing from ID to OD (fuel/PTFE interface to stainless jacket) causing breakdown of the PTFE...

I found that the high static charge can produce pin holes in the Teflon liner which causes small leaks. I guess if there is enough seepage then there is always the possibility of fire. I'm going to the PTFE in the hopes it will be a lifetime hose. Surprising how fast the years go by and I'm replacing the standard stainless covered hoses again this year. Doesn't make much sense to risk pinholes and having to go through the process again. I chickened out and ordered out the Fragola hose from Summit. Hopefully once and done.

The Teflon hose is still super stiff -- but on the plus side the fittings are easier to assemble and don't fight me near as much. If the fitting needs to come apart for whatever reason a new "olive" must be used. That little aluminum bushing deforms around the Teflon and is only good for one time. I just purchase an extra half dozen olives in case we do have to redo a fititng.

[chuckies76ta]

Mike: Thanks for posting this, and Thanks to folks who replied. I have used the Teflon lined hose for probably back 10 years ago for fuel lines. Still running it on my car. The product I bought came from Greenline here in Canada. https://www.greenlinehose.com/locations
This is the hose I used. https://www.greenlinehose.com/buy/pr...Hose/dept-2DFX
It's used for compressor discharge lines. I bought this lines with the companies machined crimp ends. I haven't had any issues with it on my car.

However, we had them on the 68 Firebird. When we had the 468 engine in the car we started to smell fuel every once in awhile while driving on the street. I checked everywhere on the car. Could not find any leaks anywhere. We have since changed engines and I upgraded the fuel lines from -6an to -8 an lines. Same material and from same company. No more fuel smell. I never could figure out if it was just too rich with the Carburetor or not. 950 Quick-fuel. The O2 sensor did show rich at times into the 10.5 to 11 reading for only a few seconds. This thread got me wondering if the fuel lines could have been an issue. So, I still have the lines and I'm gonna join them together and pressure them up to see if there is actually any pin holes in the lines. I will report back with my findings. Gotta get a few fittings and a pressure gauge.

[mysticmissle]

couple years ago, i had actually seen first hand, in a industrial extruder oil system, where the ptfe, stainless lines were sparking, and emitting and audible static shock noise. It was amazing. the electrons coming off the moving oil were looking to sort at the nearest opportunity. The fix was different style lines with external grounding.

[chuckies76ta]

Just a follow up. I put the line in water today with a little over 100 pounds in it and no bubbles. hmmm So I even took a video for 20 sec still nothing. Can't post to large a file. I'm not sure what this proves. I do like the idea of carbon infused lines. Engineers know a hell of a lot more than me.

[Vroom_vroom]

Originally Posted by lust4speed

I had found Evil Energy's listings on Amazon and prices are great... but caution is pulling me to order the Fragola hose and fittings since this should be a one time purchase. Would hate to order the cheaper hose and have to replace it in a couple of years due to pin holes.

Granted I usually just buy the bulk no name braided hose but I have been using the evil energy fittings for years with great success. Some of them have to be getting up there in age and never an issue.


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