Adding a second fuel tank

[Philip_Oceanis 361]

I would like to add a second smaller plastic diesel tank (around 40-50lt) in a lazarette to be used for transferring fuel in the primary tank rather than using jerry cans.
Is it possible to add a Y connector to the fuel tank vent hose, at some point probably low near the primary fuel tank, and connect to it a second hose that will go to that smaller tank? I could even add a filter to that hose (not sure what type though), a lever valve and of course some kind of pump (probably that squeeze pump thing since the smaller tank will be above the primary tank) to transfer the diesel from the small tank to the primary one.
Can you see any problems with this? The idea is to simplify the process of using jerry cans to refuel during a long passage.
Thanks

 

[jibes138]

Why not tee into the fuel line and return line with three way valves and just use the second tank instead of transferring fuel tank to tank?

 

[Philip_Oceanis 361]

There's really no space at all at the return line. On the contrary there's lot of space where the vent line is. So my question remains.
Thanks

 

[Benny17441]

I don't know if I follow you but it would seem to me that a shutoff valve would be needed between the small and primary tank to prevent the lower one from overflowing when both tanks are full.

 

[Scott T-Bird]

I can't see how there is any harm in trying it and I can't think of a reason it wouldn't work with a few simple precautions.

Assuming that the jerry can will be higher than the primary tank, I'm guessing that the primer (squeeze bulb) is simply to get the siphon working and your purpose is to siphon the fuel into the primary tank thru the vent line. Be sure to y into the vent line near the tank where there is no possibility where the fuel could back-up into a low point in the vent line. If your vent line has an upward slope all the way to the vent without any low points, all the better. Just make sure you don't have any residual fuel sitting in a low point on the vent line as a result of filling the tank.

Be sure that the jerry can isn't higher than the vent, in the event that you attempt to siphon into a full tank, so that you don't overflow the vent (I know, that's sort of obvious).

A assume that the "lever valve" is the shut-off valve that you would use to isolate the system just above the y to the vent line.

 

[Philip_Oceanis 361]

A assume that the "lever valve" is the shut-off valve that you would use to isolate the system just above the y to the vent line.

Yes exactly