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PTFE tubing for aviation fuel

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JOHN TIPTON

Joined: 17 Sep 2006
Posts: 239
Location: Torquay - England

Posted: Mon Aug 08, 2016 2:16 am Post subject: PTFE tubing for aviation fuel

Hi a Guys 



Is a PTFE lined SS tubing OK for aviation fuel 



http://www.exact-eng.co.uk/catalogue/300_series_smoothbore_ptfe_hose.htm 



Regards 



John

flying-nut(at)cfl.rr.com
Guest

Posted: Mon Aug 08, 2016 4:20 am Post subject: PTFE tubing for aviation fuel

Looks similar to Aeroquip 666 hose from Aircraft Spruce.

http://www.aircraftspruce.com/catalog/appages/aq666.php?clickkey=46065

JIC fittings for the teflon hose can be found at most any good hydraulic 

outlet.

I would guess that if the dimensions correlate (I don't do 'mm' very 

well) it would be great for fuel.



Linn



On 8/8/2016 6:16 AM, JOHN TIPTON wrote:

 	  Quote: 	
		   



 Hi a Guys



 Is a PTFE lined SS tubing OK for aviation fuel



 http://www.exact-eng.co.uk/catalogue/300_series_smoothbore_ptfe_hose.htm



 Regards



 John





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=459312#459312

Kellym

Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

Posted: Mon Aug 08, 2016 5:17 am Post subject: PTFE tubing for aviation fuel

I agree that the hose should be okay, however, all such hose in the US 

has to have the fittings professionally installed.  The teflon is most 

commonly used as core for integral fire sleeve tubing such as Aeroquip 

466 or Parker 124J.

I assume different tooling and fittings than your common Aeroquip 303.



On 8/8/2016 5:19 AM, Linn Walters wrote:

 	  Quote: 	
		   



 Looks similar to Aeroquip 666 hose from Aircraft Spruce.

 http://www.aircraftspruce.com/catalog/appages/aq666.php?clickkey=46065

 JIC fittings for the teflon hose can be found at most any good hydraulic

 outlet.

 I would guess that if the dimensions correlate (I don't do 'mm' very

 well) it would be great for fuel.



 Linn



 On 8/8/2016 6:16 AM, JOHN TIPTON wrote:

> 

>

> Hi a Guys

>

> Is a PTFE lined SS tubing OK for aviation fuel

>

> http://www.exact-eng.co.uk/catalogue/300_series_smoothbore_ptfe_hose.htm

>

> Regards

>

> John

>

>

> Read this topic online here:

>

> http://forums.matronics.com/viewtopic.php?p=459312#459312

>

>

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

n146wb(at)cfu.net
Guest

Posted: Mon Aug 08, 2016 5:47 am Post subject: PTFE tubing for aviation fuel

I've been using this type of hose on my RV-6 for almost 9 years with no

problems.  I did change the hose several years ago, but only because I had

to remove the engine so it was a convenient time to replace all the hoses.



--

vanremog(at)aol.com
Guest

Posted: Mon Aug 08, 2016 7:04 am Post subject: PTFE tubing for aviation fuel

Yes. but there is a concern.  Extruded PTFE can split over time due to pressure variations (pulsing from reciprocating pumps) as the hose ages.  There are better choices in elastomeric hose.

   

  -GV

   

   

  --

flying-nut(at)cfl.rr.com
Guest

Posted: Mon Aug 08, 2016 7:25 am Post subject: PTFE tubing for aviation fuel

Hmmm .... the description on ACS says       "Construction of Aeroquip 666 hose is of spiral extruded Teflon™       resin" which may be different for hose just "straight extruded"       ..... YMMV

       Linn

       On 8/8/2016 11:04 AM, vanremog(at)aol.com (vanremog(at)aol.com) wrote:

     

     [quote]         Yes. but there             is a concern.  Extruded PTFE can split over time due to             pressure variations (pulsing from reciprocating pumps) as             the hose ages.  There are better choices in elastomeric             hose.

          

         -GV

          

          

         --

vanremog(at)aol.com
Guest

Posted: Mon Aug 08, 2016 7:51 am Post subject: PTFE tubing for aviation fuel

I should correct my info.  Apparently this early problem has since been corrected in all PTFE hose sold for fuel use.

   

  Sorry for the misstep.  I didn't mean to muddy the water.

   

  -GV

   

   

  --

rampil

Joined: 04 May 2007
Posts: 870

Posted: Mon Aug 08, 2016 11:11 am Post subject: Re: PTFE tubing for aviation fuel

The PTFE you choose should also have an internal conductive strip to prevent static discharge

_________________
Ira N224XS

Kellym

Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

Posted: Mon Aug 08, 2016 12:21 pm Post subject: PTFE tubing for aviation fuel

I don't know if you can buy the necessary fittings and hose for 

experimental aircraft. I know that no hose shop will sell the Aeroquip 

466 or Parker 124J as raw hose. You have to buy pre-made on the integral 

firesleeve version. It may have to with the molded firesleeve on the 

outside, and not the fittings. Aeroquip 666 may be different, so I may 

have mis-stated the requirement.



On 8/8/2016 6:42 AM, Linn Walters wrote:

 	  Quote: 	
		   Kelly is correct.  The aeroquip 491-X fittings for the  aeroquip 303

 hose are not compatible with the aeroquip 666 braided stainless teflon

 hose.  The F-66000-X for the 666 hose has a 'flare' on the hose side.



 All the fittings like this that I've seen are steel .... which is what

 you want under the cowl ...... haven't seen any aluminum ones yet.

 The F-66000-X fittings go together with two wrenches and do not require

 a mandrel like the 303 hose fittings or being crimped.

 I wasn't aware of the requirement that the fittings be 'professionally

 installed'.  I'd like Kelly to expand on that ...... what's that phrase

 mean??

 Linn



 On 8/8/2016 9:17 AM, Kelly McMullen wrote:

> 

>

> I agree that the hose should be okay, however, all such hose in the US

> has to have the fittings professionally installed.  The teflon is most

> commonly used as core for integral fire sleeve tubing such as Aeroquip

> 466 or Parker 124J.

> I assume different tooling and fittings than your common Aeroquip 303.

>

> On 8/8/2016 5:19 AM, Linn Walters wrote:

>> 

>>

>> Looks similar to Aeroquip 666 hose from Aircraft Spruce.

>> http://www.aircraftspruce.com/catalog/appages/aq666.php?clickkey=46065

>> JIC fittings for the teflon hose can be found at most any good hydraulic

>> outlet.

>> I would guess that if the dimensions correlate (I don't do 'mm' very

>> well) it would be great for fuel.

>>

>> Linn

>>

>> On 8/8/2016 6:16 AM, JOHN TIPTON wrote:

>>> 

>>>

>>> Hi a Guys

>>>

>>> Is a PTFE lined SS tubing OK for aviation fuel

>>>

>>> http://www.exact-eng.co.uk/catalogue/300_series_smoothbore_ptfe_hose.htm

>>>

>>>

>>> Regards

>>>

>>> John

>>>

>>>

>>>

>>>

>>> Read this topic online here:

>>>

>>> http://forums.matronics.com/viewtopic.php?p=459312#459312

>>>

>>>

>>>

>>>

>>>

>>>

>>>

>>>

>>>

>>>

>>>

>>>

>>

>>

>>

>>

>>


>

>

>

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

flying-nut(at)cfl.rr.com
Guest

Posted: Mon Aug 08, 2016 12:39 pm Post subject: PTFE tubing for aviation fuel

OK, I'll bite.  Why?  The fuel in the hose is too rich to ignite even if 

it gets lots of air in it, and the steel ends are connected by the 

stainless steel braid.

I agree that having the conductive strip would further lessen the 

possibility of static discharge but don't see it as an absolute 

necessity.  But then, if we were anal about removing all possible risk 

.... we probably wouldn't fly an experimental airplane ..... IMHO of 

course.

Linn



On 8/8/2016 3:11 PM, rampil wrote:

 	  Quote: 	
		   



 The PTFE you choose should also have an internal conductive strip to prevent static discharge



 --------

 Ira N224XS





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=459335#459335

ceengland7(at)gmail.com
Guest

Posted: Mon Aug 08, 2016 1:30 pm Post subject: PTFE tubing for aviation fuel

Without some form of conductive material in the liner, the fuel moving 

through the line can generate a large static potential. It's not an 

issue inside the hose, it's the 'potential potential difference' the 

beginning and end points that pose a risk. The conductive liner 

'prevents static discharge' by bleeding off any charge as it develops 

(or prevents its development). Really no different from the requirement 

that you ground the a/c before fueling; it keeps both ends at the same 

electrical potential so there can be no spark from charge equalization.

On 8/8/2016 3:38 PM, Linn Walters wrote:

 	  Quote: 	

 OK, I'll bite.  Why?  The fuel in the hose is too rich to ignite even 

 if it gets lots of air in it, and the steel ends are connected by the 

 stainless steel braid.

 I agree that having the conductive strip would further lessen the 

 possibility of static discharge but don't see it as an absolute 

 necessity.  But then, if we were anal about removing all possible risk 

 ..... we probably wouldn't fly an experimental airplane ..... IMHO of 

 course.

 Linn

 On 8/8/2016 3:11 PM, rampil wrote:

> 

>

> The PTFE you choose should also have an internal conductive strip to 

> prevent static discharge

>

> --------

> Ira N224XS

gyoung

Joined: 09 Jan 2006
Posts: 211
Location: Republic of Texas

Posted: Mon Aug 08, 2016 1:57 pm Post subject: PTFE tubing for aviation fuel

I get that but why does it have to be in the liner To restate Linn's point - Doesn't the SS braid connected to the metal fittings on both ends equalize the potential?



--

flying-nut(at)cfl.rr.com
Guest

Posted: Mon Aug 08, 2016 2:09 pm Post subject: PTFE tubing for aviation fuel

I got this answer in an offline email ...... thought it should be shared 

.....



The issue with non conductive Teflon hose is that over time it will leak.  The fluid flowing through it creates static discharge which over time will create pinhole leaks and cause the hose to seep.



Linn

On 8/8/2016 5:56 PM, bigdog(at)bentwing.com wrote:

[quote] 



 I get that but why does it have to be in the liner To restate Linn's point - Doesn't the SS braid connected to the metal fittings on both ends equalize the potential?



 --

ceengland7(at)gmail.com
Guest

Posted: Mon Aug 08, 2016 2:32 pm Post subject: PTFE tubing for aviation fuel

If we ignore the possibility that the stainless braid connection could 

fail, there's still the fact that the fuel itself will take on a charge 

as it flows through the line (if the line isn't conductive). I did a 

quick google search trying to find an easy technical description, & 

stumbled onto another reason for the conductive liner (that I've read 

about, but had forgotten).

http://ionixgastechnologies.com/Static%20Control%20in%20PE%20Fuel%20Gas%20Pipe.pdf

The link is about 'natural' gas; not liquid fuel, but the same principle 

applies. Static buildup in the fuel can actually discharge *through* the 

non-conductive liner into the grounded braid, burning pinholes in the 

liner. Here's a link to a mfgr's page on the type of line we're discussing:

http://racetronix.com/press-release/551/



I'll bet you can't even find a fuel-rated PTFE lined hose these days 

that doesn't have  a conductive material added.



Charlie



On 8/8/2016 4:56 PM, bigdog(at)bentwing.com wrote:

[quote] 



 I get that but why does it have to be in the liner To restate Linn's point - Doesn't the SS braid connected to the metal fittings on both ends equalize the potential?



 --

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