Connections in fuel lines

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saltyrob

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Good Afternoon,

I am replacing the diesel fuel tank in our yacht which presently has 5/16 inch copper fuel lines.The new installation will be slightly different and for ease of installation in a confined space
I would like to extend the existing pipework in 5/16 fuel grade nylon pipework.Is there a correct way of joining the two different pipe materials. I have had a quick look on the ASAP Supplies site and on the web and have not found any fittings for the purpose. Is pushing the nylon pipe over the copper and securing with clips satisfactory

Your advice and info on where fittings may be purchased would be much appreciated

Many thanks

Rob
 
Most advice on fuel lines is to use copper throughout if possible to minimise the fire risk. Nylon would simply dump fuel into the hottest part of the fire when it melted! It's normal practice to only use flexible hose from the final fuel tap to the engine and even then only if the engine is flexibly mounted. You don't say whether the nylon line is 5/16 ID or OD - presumably ID or else it wouldn't slide onto the copper pipe. I would be amazed if a clip would compress nylon enough to make it grip onto a solid pipe.

Surely if you're fitting a new tank, this is the ideal time to install new solid fuel lines BEFORE the new tank goes in?

Rob.
 
Hi

Agree that compressing nylon pipe onto copper tube does not seem correct. Are there copper to copper connections available as would like to keep most of the present copper pipework.

I would say that the nylon fuel line would be used near the tank which is remote from the engine and any source of heat. If fire reached the fuel tank area the situation would already be critical.

Rob
 
Our fuel line comes out of the tank as a copper pipe which terminates near to the tank. The remaining run to the primary filter and then on to the engine is by flexible lines - no idea if they are some breed of rubber or plastic. The joins between the copper and flexible pipes are simple jubilee clips. Seems to be pretty much industry standard when looking at other folks engines; short run of copper into the tank and then flexible pipes to run to the engine; same for the fuel return line. To my mind, the problem with copper is the ease with which it fractures when subjected to vibration, think its called work hardening. No doubt VicS will be along shortly to comment as well.....

Forgot say that the heater fuel supply is all plastic/rubber. There's a plastic skin fitting into the tank, which terminates to a flexible pipe which then runs to the heater.
 
Like the OP 'saltyrob', I'm interested in the thoughts of the experienced-in-dieselery on joining copper tube and 'flexible' tubing - and how.

My fuel return pipe has a length of flexible stuff joined to some ill-supported copper tubing ( that's the way the previous owner had it, and I'm intent on changing this for the better )using small jubilee clips. It weeps - unsurprisingly. I cannot imagine how a jubilee clip can exert enough pressure to effect a seal on straight 'un-belled' piping, without risk of collapsing the walls.

Now, I also have straightforward copper piping feeding from the tank to the primary fuel filter, the last part of which is inadequately supported at present. I want to fit a manual 'squeeze' bulb ( as used in outboard fuel supply lines ) into this feed-pipe to facilitate fuel bleeding. Arrangements for secure clipping of copper-to-plastic here would seem to need the same as those to be provided on the return pipe. Conscious that such a bulb could be vulnerable to melting in event of engine fire, perhaps this bulb and its stub-connections could be shielded - and supported - behind a piece of plumber's mat.....

What is the optimum way to arrange the cut ends of copper tube which are to be mated with flexible fuel line tubing?
 
I join copper to BS7840 rubber all the time, but in smaller bore for heaters, however compression fittings are available to do it in 5/16" (5/16" copper to 5/16" hosetails) too, mostly though I form the ends and then use fuel line clips to clamp the rubber hose to the tube which is what is the best way. If you don't have a tool to form the ends of the copper I guess second best would be to solder on some 5/16" olives or use the compression hosetails, or take the copper to the likes of Pirtec who would form the ends for you.
 
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A very dodgy plan. Fuel lines should be run in solid copper with a flexible reinforced fuel grade hose to the engine. This hose should have swaged copper tails on each end so they can be connected with normal compression fittings. You might like to consider your insurance before taking any further steps.
 
PCUK said:
A very dodgy plan. Fuel lines should be run in solid copper with a flexible reinforced fuel grade hose to the engine. This hose should have swaged copper tails on each end so they can be connected with normal compression fittings. You might like to consider your insurance before taking any further steps.
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Both my Benes came with rubber from and to the tanks. The Eber on this one was fitted by the main dealers in Ireland, it uses nylon and rubber hoses.
Stu
 
Are you not allowed to BS7840 rubber lines throughout? It would be a lot easier to install.
 
skipper_stu said:
Both my Benes came with rubber from and to the tanks. The Eber on this one was fitted by the main dealers in Ireland, it uses nylon and rubber hoses.
Stu
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Perfectly acceptable, nay, approved practise both for RCD and BSS provided the ends of the copper are formed and the rubber lengths are kept to the necessary minimum, as I said I do it all the time and it is the correct and approved way to do it. You must use BS7840 hoses though, but reinforcement is not called for. That said, many heating installs I have inspected do not have the copper ends formed and obviously it is impossible to confirm without some dissasembly.
 
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Hi

Many thanks for all the info.Can anyone guide me to a supplier of compresion fittings for joining nylon fuel line to copper . Would be nice id supplier was in Suffolk/Ipswich area.

Rob
 
saltyrob said:
Hi

Many thanks for all the info.Can anyone guide me to a supplier of compresion fittings for joining nylon fuel line to copper . Would be nice id supplier was in Suffolk/Ipswich area.

Rob
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If you insist on using the wrong thing (nylon) then I can not help, however if you like I will provide you with the right BS7840 rubber hose and the copper compression to hose tails and clips this weeked as I will be on my boat in Shotley and can bring them with me.
 
The fuel lines on the Kipper were installed by Foxs. There were the correct rubber onto compression fittings but were attached using jubilee clips, on the return this cut through the hose and I've had to repair - should jubilees be used or is there a more suitable clip?
 
Hi

Sorry David ,(2452), I meant proper rubber tube

We are not quite ready yet as just planning things ,but thank you for you kind offer

Regards

Robert
 
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