Dual fuel tanks

[Weyalan]

Originally Posted by GordMay

The fuel supply & return should always be plumbed to the same tank.
Don't use "crossed" returns to effect fuel transfer.

Care to elaborate, Gord?

[knottybuoyz]

Originally Posted by DeepFrz

Idiot proof things are for idiots...

What if a single fuel line, whether feed or return, gets clogged, or if the draw or return is a little uneven?

What if a fuel line springs a leak?

What then, eh?

*Sigh* Maybe I better just quit boating and buy a rocking chair for my porch! *Sigh* You're such an enlightening "Ray of Sunshine" Frz!

[GordMay]

Returning the excess cooling/lubricating fuel to “another” tank (other than the supply tank from whence it came) will (eventually) result in an overflow in the “other” return tank.

Diesel injection pumps take more fuel than they actually inject and use for combustion. It is important to supply “extra” fuel to the injection pump, so that fuel may be used to cool and lubricate the system, before bypassing it back to the tank. The extra fuel, not used in combustion, is returned to the supply tank, through the return line.

[DeepFrz]

Yeah, well I got time to think of these things as I sit here rockin...<G>

And while I sit here rockin, I like to help people make the right choices.

[knottybuoyz]

Originally Posted by DeepFrz

Yeah, well I got time to think of these things as I sit here rockin...<G>

Still winter out there in Winterpeg ain't it FRZ?

Ya must have snow runners on your rockin' chair!

Still think I can make an "idiot proof" fuel system! Stay tuned!

[GordMay]

Ah, my home town (the Peg), once the snow melts, the skeeters’ll eat you alive.

[DeepFrz]

Rick, Gord, it's 34 c with a humidex reading of 41. Haven't seen a skeeter in weeks although one buzzed my ear about a week ago. I have never seen a summer with so much rain and so few mosquitos, at least where I live, near Assiniboine park,

I was talking to some folks last week that said the skeeters were bad where they live, but I walk a lot and have used repellant twice this year. It's amazing what can be done when the West Nile Virus threat is high.

I'm sure looking forward to some cool weather though. This heat knocks me out...<g>

Rick, I'll keep an eye on your fuel system design and when you get it right I'll let you know...<G>

[Weyalan]

Originally Posted by GordMay

Returning the excess cooling/lubricating fuel to “another” tank (other than the supply tank from whence it came) will (eventually) result in an overflow in the “other” return tank.

Diesel injection pumps take more fuel than they actually inject and use for combustion. It is important to supply “extra” fuel to the injection pump, so that fuel may be used to cool and lubricate the system, before bypassing it back to the tank. The extra fuel, not used in combustion, is returned to the supply tank, through the return line.

I understand all of the above, Gord. However I don't see how it constitutes and argument against using your fuel retrun system to transfer fuel from one tank to another? The rate of flow of fuel out of the engine and back to the "other" tank is very slow, so it is very easy to monitor the state of fill of the "other" tank and, as it approached full, either switch your return back to the original tank (assuming it still contains fuel) or switch your fuel into the engine onto the "other" tank.

Really, it is just a simple, slow ballast system.

[coot]

Originally Posted by Weyalan

The rate of flow of fuel out of the engine and back to the "other" tank is very slow, so it is very easy to monitor the state of fill of the "other" tank and, as it approached full, either switch your return back to the original tank (assuming it still contains fuel) or switch your fuel into the engine onto the "other" tank.

You can't ignore human factors. People WILL get tired, distracted, etc, and fail to implement procedures perfectly. When that happens, you want to have systems that minimize the damage.

Someday, you'll be really tired because you dragged anchor 3 times the night before. Or you are boarded by the coast guard because they mistake you for that terrorist/drug-dealer/whatever they're looking for. Or you are injured and a less experienced crew member has to take over. Or it is just really hot today. Something like this happens, you forget to monitor the tank closely enough, and you end up pumping fuel overboard.

I would not have thought this such a big deal before I started sailing, because you just don't get the same human factors issues working in an office environment. Since I've been out there, though, I've experienced the diminished ability that comes from fatigue, heat, cold, seasickness, etc. At first, it is surprising; later, it is the way life is, and you plan for it.

Now I would even prefer not to have TWO valves where BOTH have to be switched. Isn't there a device with two valves and one knob, made especially for this situation?

[DeepFrz]

The only double valves I have seen are made for aircraft and are very expensive. In aircraft they are required so that the return is always sent back to the supply tank, you have no choice. It is for exactly the reason that coot talks about, fatigue and distraction. On a boat you probably wont be switching supply tanks very often and so separate valves are allowed, although I would hope that they are very close and arranged so that there can be no confusion. Well, in my case as little confusion as possibel...<g>

[vacendak]

Have same problem and will do installation with 2 Y-valves
the only appropriate valve found nearby is GROCO TS 350




any other usable brands & models known ?

many thanks

[Evan]

What you can do is fit 2 x 3 way valves, but fit a linkage bar between the 2 valves, such that you can only change one valve as the same time as the other. It is pretty much idiot proof.

"Seachoice" makes a budget version but no experience with it.

[vacendak]

thanks Evan

found Seachoise in WWW; seems to be a trader, not producer
still: GROCO has also a 6-port valve

Six port fuel valves are used where 2 tanks supply a single engine and a return to each supply tank is required

That should do it

[GordMay]

GROCO 6-Port Fuel Valves,#FV-65038 and #FV-61075, provide flow to or from either of two connected tanks with its "L" shaped flow pattern and 180-degree handle actuation. FV-65038-A and FV-61075-A provides flow to or from either connected tank or both tanks simultaneously with its "T" shaped flow pattern and 360-degree handle actuation.

Goto: GROCO MARINE PRODUCTS
Select PRODUCTS, then VALVES

#FV65038 sells for $149.95 at:
http://www.discountmarinesupplies.co...UEL_VALVE.html

[vacendak]

thanks, Gord

HAPPY NEW YEAR :cubalibre