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Old 03-07-2012, 16:29   #1
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Fuel Transfer / Polishing Through Return Manifold ?

I am not a diesel expert, my question is: will a small amount of back pressure up the return line while the motors are off cause any problems? Motors are 2x ford lehman 120 and 1x westerbeke 15kw genset.

Basically, right now i move/clean fuel via a fix mounted transfer pump plumbed to the main fuel manifold. To operate, I shut off the engine pickups on the manifold, attach a quick-fitting adapter to the "draw" tank that "jumpers" the bottom of the tank to the fuel pickup line (to draw from the very bottom of the tank, if desired), and finally string a line across the engine room to the desired "fill" tank and attach another quick fitting.

I don't like this system because i end up with an irritating 15' line filled with diesel, and it is just a hassle overall. I don't mind the bit with jumpering the bottom of the tank to the regular fuel draw (its a much shorter run, and most of the time i don't care to draw right off the bottom... only when i suspect there may be water in the tank).

What I would like to do is just simply plumb the transfer pump to the return manifold, and use the existing return lines to send fuel back.
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Old 03-07-2012, 17:36   #2
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Re: Fuel transfer/polishing through return manifold?

Yes that would work
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Old 03-07-2012, 18:04   #3
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Re: Fuel transfer/polishing through return manifold?

My fuel polishing system returns fuel to the tank via a common return line shared with the main engine and generator.
The polishing picks up from the very bottom of the tank and I think that is important.
I only have one tank. With two you need to be careful you are not emptying, or overfilling a tank. A series of valves are not expensive and this ensures that the fuel does what you want it too.
It's also easy to arrange the valves so that fuel for the main engine can obtained from either the main engine primary filter or the generator primary filter. For boats without a generator the fuel polishing filter can be used a emergancy filter for the main engine in the event of a blockagage.
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Old 03-07-2012, 20:26   #4
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Re: Fuel transfer/polishing through return manifold?

Thanks for the answers.

Quote:
Originally Posted by noelex 77 View Post
My fuel polishing system returns fuel to the tank via a common return line shared with the main engine and generator.
The polishing picks up from the very bottom of the tank and I think that is important.
I only have one tank. With two you need to be careful you are not emptying, or overfilling a tank. A series of valves are not expensive and this ensures that the fuel does what you want it too.
It's also easy to arrange the valves so that fuel for the main engine can obtained from either the main engine primary filter or the generator primary filter. For boats without a generator the fuel polishing filter can be used a emergancy filter for the main engine in the event of a blockagage.
I made this diagram just for the hell of it, this is how i have it set up (except have to put transfer pump in still)... there are also some vacuum gauges, lift pumps and bypass valves but i left those off the diagram for simplicity:
Click image for larger version

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Yes drawing off the bottom for polishing im sure will be better, however i just cleaned the tanks last year (and i plan on cleaning them again when the filters start picking up dirt regularly), and my main use of the system will just be transfer, and the cleaning just a bonus.

I get nervous when running below around 1/3 of a tank (too easy to forget about things and end up bleeding 3 engines while floating near some rocks), so i would prefer to be able to move fuel up into one or two tanks as levels start to get low without having to run lines and make connections.


I prefer to have the filters dedicated to "tanks" rather than "engines". This way if one tank is causing a problem, i can quickly switch to the other tank/filter in one shot by flipping a valve. If a filter clogs up/fills with water, chances are, the tank that is being drawn on has some bad fuel in it and this will need to be dealt with before continuing to use the tank. If multiple filters are in action at the same time, its easy for them to get filled with water or clog all at once, leaving you dead in the water.

For example, a couple weekends ago i was out and all of a sudden both motors started surging after switching to the port tank i had just filled. It turned out the fuel dock had sold me some watery fuel (enough water to fill the racor's separator, and then some). I quickly switched to my stbd tanks, and dealt with the port side filter/tank when I got to the dock (ended up having to drain about 10L of diesely water out of the fwd port tank).

Ideally I would have 5 filters... one for each tank + one for the transfer system (and separate it completely)... but that is kind of much i think.
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Old 03-07-2012, 21:04   #5
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