Fuel Line SAE rating

[Villeman]

Hi,

 

i know this was discussed often but I can´t find that aspect right now. The fuel lines are 5/16 or 8mm SAE 30R9. Problem is, I can only get SAE30R6 rates stuff (which still has 20 bar of pressure resistance though... so more than plenty since operating pressure is around 12bar)  is there any reason why this shouldn´t work? I will use it around the tank mainly but want to also use it for the injectors (its 15mm OD so that may not be possible)

 

 

thanks,
Richard

 

[Chickenman]

Do not use the 30R6. This is a low pressure fuel hose and it is not designed to be used with Fuel Injection systems. While the pressure rating may seem enough, that is the BURST pressure... which is not the same as working pressure. Working pressure is the pressure that the hose has to withstand in constant use over it's lifetime. 30R76 only has to meet  a working pressure of 50 psi. 

Even used as a non pressure tank feed, 30R6 is an old standard and causing issues. 30R6 is causing a lot of issues in North America with the new formulation of fuels. Damage from Ethanol and  excessive permeability being the major problem.  New fuels require at least the 30R9. Note. Since you live in Germany the European specs may be different part number. I find it hard to believe you can't find appropriate specification hose in Germany. European standards are usually higher than North America. 

Here's ane article from Pelican Parts forum. It usually has a pretty good reputation, as they have a lot of Porsche and BMW club racers who contribute.

http://forums.pelicanparts.com/porsche-911-technical-forum/671288-sae30r6-kx-fuel-line.html

And here is a link to SAE documentation on the standards. 

http://www.volksbolts.com/faq/SAEJ30.pdf

 

Quote

4.4 Low-Pressure Coupled and Uncoupled Synthetic Rubber Tube and Cover (SAE 30R6), (SAE 30R7), (SAE 30R8) Hose which may be supplied either coupled or uncoupled for use with gasoline, diesel fuel, lubrication oil, or the vapor present in either the fuel system or in the crankcase of internal combustion engines in mobile, stationary, and marine applications. Exposure of these hoses to gasoline or diesel fuel which contain high levels, greater than 5% by volume, of oxygenates, i.e., ethanol, methanol, or MTBE (methyl tertiary butyl ether), may result in significantly higher permeation rates than those listed for 30R6, 7, or 8. This hose is for maximum working pressures of 0.34 MPa (50 psi) up to and including 9.53 mm (3/8 in) ID and 0.24 MPa (35 psi) for over 9.53 mm (3/8 in). For 30R6 hose in excess of 25.40 mm (1 in), the working pressure is 0.11 MPa (16 psi). The hose may be furnished in long lengths, specific cut lengths, or as a part preformed to a specific configuration. This hose is suitable for use in temperatures up to 100 °C (212 °F) for 30R6, 125 °C (257 °F) for 30R7, 150 °C (302 °F) intermittently and 135 °C (275 °F) continuously for 30R8. The construction of this hose embodies a smooth bore tube of fuel- and oil-resistant synthetic rubber compound, suitably reinforced with textile fiber yarn, cord, or fabric, and a cover of suitable oil-, ozone-, and heat-resistant synthetic rubber compound

 

 

[Zed Head]

Here's a good reference, in addition - http://www.gates.com/oreilly/PDFs/Fuel Systems.pdf

[Chickenman]

Delete. Double Post

 

Edited April 1, 2017 by Chickenman

[Villeman]

okay, good to know... the problem was that i need to do a SAE to DIN conversion since nobody uses SAE here, at least thats the impression I got. I now switched to LPG CNG hoses a store had from LPG conversions back there, should work, but I will hunt down proper hoses and use them.

 

Thanks!

[Stanley]

After finding little bits of black debris in the float bowls I changed all the hoses to USCG rated marine hose. Costs 8 times as much but you only need a few feet. It has an ethanol resistant liner. Also fire resistant. Didn't check pressure rating since it's not an issue with carbs. It's thicker and stiffer than ordinary non-F.I. hose, so F.I. style clamps required.

[siteunseen]

2 hours ago, Stanley said:

After finding little bits of black debris in the float bowls I changed all the hoses to USCG rated marine hose. Costs 8 times as much but you only need a few feet. It has an ethanol resistant liner. Also fire resistant. Didn't check pressure rating since it's not an issue with carbs. It's thicker and stiffer than ordinary non-F.I. hose, so F.I. style clamps required.

That's a good idea, thanks.  Preventive maintenance at it's best. 8^)

[Villeman]

well, I now got steel mesh fuel line tube with 50 bar (725psi) burst pressure and 20 bar (290psi) operating pressure, ethanol and petrol resistant...

If it blows up it blows up....

 

Edited April 24, 2017 by Villeman