T&T: Fw: Fuel Manifolds

[Larry N. Brown]

> Conceptually the day tank (provided the fuel is returned from the
> engines to it) becomes an automatic master manifold.  If one fuel supply
> tank is designated as the main tank, the system could operate without
> any valves to manipulate.   An adequate fuel transfer pump system could
> supplement the main tank from any additional tanks, and these supply
> tanks wouldn't need to be at the same level.   Fuel polishing and other
> capabilities would be easy to incorporate.  I'll try to put my design
> ideas in a subsequent post.
>
> BTW, have any of you found ganged valves (tee and shutoff) suitable for
> simultaneous fuel handling?
>
> Gary Bell
>

Gary,

 I took a slightly different approach to my fuel system. I have two saddle 
tanks and 2 belly tanks, one forward and one aft. I specified separate 
machinery and polishing/transfer suctions and returns for each tank. The 
machinery pickups are situated about 3/4" from the bottom and the 
polishing/transfer are about 1/4" off the bottom. Fuel returns are 
relatively deep in the tank to prevent foaming and to stir up any possible 
crud in the bottom. I designed a panel which has 4 pairs of 5 way valves. 
The upper 4 valves are suction and the lower 4 are returns. From left to 
right there's an over and under pair for port engine, genset, starboard and 
polishing/transfer. While it's possible to transfer using main or genset 
feed fuel, one look at the board makes it easy to insure suction and return 
are to the same tank. Any engine or genset can run off and return to any 
tank.

Now polishing/transferring is accomplished by a Walbro 6802 continuous flow 
diesel pump sucking fuel from a tank through a F-1 filter and returning it 
to a tank through the 4th pair of valves. If I'm polishing, I insure the 
valves are parallel, or that I'm sucking from one tank and returning to the 
same one. and I turn on a spst switch. When transferring, I make a 
calculation about how much fuel I want to transfer, do the math and set a 
spring powered timer switch instead.

Fuel for any engine or genset is sucked through selectable, paralleled, 
Racor 500's with a glass sight gauge and vacuum gauge in the line for 
monitoring. The system allows for great flexibility in fuel filtration, 
redundancy and boat trim capability.

Regards,

Larry and Teri
M/V Cigano, 47' Prairie Sundeck Cruiser
Lying: Covington, LA
N 30 26.7
W 90 07.1