Fuel line ID and OD Help needed
Turbo Mini Forums

Hey people.

I am nearing the stage of fuel lines and i have been looking through several pages on here (via the search box) relating to diameter of the fuel lines everyone is using.

Most people seem to be using an 8mm fuel line main feed with a 10mm diameter fuel return pipe from the regulator.

The problem i have is, is the 8mm the ID and the 10mm the ID of the copper or rubber pipes people are using. Or is this the OD???

It may be a simple and silly question but help is much appreciated :)

ID mate.

http://photobucket.com/quintonrose

Generally copper etc. (ie, rigid) tubing of these small sizes are quoted on their ODs.

But just to confuse matters, rubber (ie, flexible) tubing is usually quoted on its ID.

Copper microbore tubing for example, 10mm is 10mm OD, 1mm wall so 8mm ID.
8mm copper is 8mm OD, 0.8mm wall so 6.4mm ID.
Original steel tubing tends to be a bit thinner than copper so the ID is a bit bigger for a given size.

The rubber tube is ID to match the rigid tube OD (so it fits over nicely) and the rubber tube's OD goes up wth pressure rating as the wall gets thicker.

But this is a generalisation, not all manufacturers follow these "rules".

Did that make any sense ???

Schrödinger's cat - so which one am I ???

Cheers fellas.

Yes Rod that does make sense. So with your theory if i want to use copper pipe (which i do), I need to order 12mm pipe for the return and 10mm pipe for the main feed, if generally the wall thickness is roughly 1mm? Is this right?

:)

Best thing to do is decide what ID you want guessing 9mm and 11mm then go find it in copper for it. But microbore is normally 8mm ID.

Edited by quinton on 18th Nov, 2010.

http://photobucket.com/quintonrose

I use 8mm (OD) copper pipe for feed and return Bill

Copper microbe tubing is to (BS) EN 1057,

Here's the table

http://www.ukcopperboard.co.uk/literature/...N-Standards.pdf

Measured on OD, then deduct 2 X wall thickness.

One apology from earlier, the stuff I used was actually 0.7mm for the 10mm OD (not 1mm like I said) and 0.6mm for the 8mm (not 0.8mm like I said).

As you can see from the table, various wall thicknesses are allowed under the standard, the marking on the packet (or tube itself) will tell you which it is.

But it all starts from the OD for rigid tubing of small sizes.

So when people say they have used 10mm and 8mm OR 8mm and 8mm, that is the OD for the rigid tubing.

Opinion seems to be split whether 8mm/10mm flow/return OR 8mm/8mm but they will be ODs if copper or small bore steel has been used.

Schrödinger's cat - so which one am I ???

Cheers Rod, Oli and Quinton for your help.

Hardline is nearly always OD.

Soft hose, ie rubber etc, is nearly always ID.

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