fuel tank_fuel line

hello all..

i'm new here and found that the forum is very informative..there is one question i need to ask, and whether anyone can help me out on it..there was a discussion on the position of the fuel line on the tank..referring to attached pic below, which is most suitable location, #1 or #2 ? .. is there any regulations pertaining to this arrangement..thank you

 

It is considered safer to suck from the top of the tank, less chance of a leak, and easier to not suck up gunk from the tank bottom.

USCG only accepts top feed for inspected commercial vessels.

FAST FRED

 

There is probably a ton of regs depending on where you live . However I have no doubt in my ming that #2 is by far the best. Infact #1 should not be allowed.

Why you would want to draw fuel from above the bottom I cant immagine. If you have water there then get it out and into the filter where it can be discarded. You will no doubt have water traps any way so use them.

If water is left in the tanks it can rust the tank if its steel or at least encourage the growth of cladesporioum resinea ( fuel bug) This is a nasty stuff that grows niether in the water or the fuel but in the membrane.

In my opinion it would be less of a problem if your #2 were used. In my last boat I had 3000 liters and all tanks were your #2 I stored fuel for years and the fuel and the tanks were totally uncontaminated. I have also just modified a Nauticats fuel tanks to this method.

 

Why you would want to draw fuel from above the bottom I cant immagine.


Nigel Calder in "Marine Diesel Engines" says
If tanks are placed below an engine, all fuel connections can be made through the top of the tank. If a fuel line ruptures, this will prevent the entire contents of the tank from draining or siphoning into the bilges.

He also says the fuel fill line extended inside the tank reduces foaming when filling.

 

thank you all for your input..i worked for a company which built sandwiched FRP yacht, mainly for export..in my six year, i've seen that all the fuel line installation is from the tank top to bottom..there's some pictures below showing the arrangement of fuel tank built by us..both in FRP and stainless steel..we never build in aluminum, well as far as i can remember..this argument came about whether top or bottom fuel line is more efficient due to one boat, having top fuel line, encounter some engine problem, fuel starvation..the woner checked with someone, and he's been told that the fuel line should run from bottom, gravity feed, thus increase the fuel flow..with that reason he said the top installation is not correct..but we told him that we been installing fuel tannk with top fuel line and never had any problem..later on, found that there was some leakage in the fuel line, thus the starvation ? .. anyway, the owner insist on having it run from the bottom..well just want to share the reason behind the question asked..i'm not with marine background but i pickup bit and pieces as i go along, i have a degree in mechanical engineering..guess we'll stick with the top fuel line ..thanks


p/s: picture of boat that we built for Mikelson Yachts Inc., deisgned by Tom Fexas ..hull.9, 61ft Sportfisher..we delivered 9 of this boat..



hudson

 

I think there is some misunderstanding here. Its not that you draw the fuel from the top or the bottom I thought the question was do you take fuel from the very bottom meaning water as well or any other contaminents that would be at the bottom. The methiod of taking it from the top means that you have a pipe inside the tank to the bottom ,--but its not right at the bottom otherwise fuel would not go up the pipe due to the pipe touching the bottom.

In my opinion as previously stated it is better to draw the fuel from the very bottom ( the very very bottom point of the tank) taking ALL contaminents out into the filters.

 

This is a good thread.

I agree with Jack's thoughts, but I have personally had an accident that siphoned about 30 gallons of diesel into my bilge. The bilge pumps handled it...but friends at a neihboring slip were not pleased with the rainbow on the water that night, and traced the slick back to my boat. That was from a "top fed" tank, where the leak was in a hose below the bottom of the tank, so the siphon continued to run. I agree that "top fed" is safer, and even then not fool proof. Yes, I am the fool.

In any seas at all, the gunk mixes and is filtered with use, so I would personally argue that there is no great advantage...from a fuel polishing perspective...that the fuel feed originate from the bottom of the tank.

I learned something from thinking about this topic, so my hat is off to all contributors. A worthwhile conversation.

Mike