Fuel return to tank with multiple tanks/engines

[Jassira]

I am re-plumbing my fuel supply system and have concerns over the fuel return to tank line.

I have a Ford 2712E 80hp main engine, a 4.2kva Panda type generator with Faryman engine , 2 main fuel storage tanks and a day tank.

The engine and generator can draw fuel from any tank, I would like to return the fuel to the tank it was drawn from. I've sorted the plumbing and now have both return fuel pipes tee'd together and returned to the correct tanks, my worry is that when just one of the engine/generator are running, the non running engine will have positive pressure one the wrong side of the fuel return port. Is that a problem, could I end up with fuel flowing back through the injector pump and would it be a problem if I did. Do I need to fit non return valves, if so, what sort of pressure should they operate at.

Thanks
Nigel

 

[paul-essex]

the return is low pressure and should not be a problem but if you are pushing the return into a tee between two tanks it could come from one to the engine and fill the other one up on the return and over flow unless you put a valve in the 2 returns or switch over .
unless both tanks are level with each other and have a balance pipe

I would look into supplying both engines from one tank ( the lower one ) then have a pipe from the highest one and a valve in the line to top it up when it is low
or if the two tanks are the same level pipe one tank to one engine put a low level balance pipe between them with a valve in line to isolate them if needed

 

[Jassira]

the return is low pressure and should not be a problem but if you are pushing the return into a tee between two tanks it could come from one to the engine and fill the other one up on the return and over flow unless you put a valve in the 2 returns or switch over .
unless both tanks are level with each other and have a balance pipe

I would look into supplying both engines from one tank ( the lower one ) then have a pipe from the highest one and a valve in the line to top it up when it is low
or if the two tanks are the same level pipe one tank to one engine put a low level balance pipe between them with a valve in line to isolate them if needed

Thanks for that... I've probably confused the issue by mentioning about multiple tanks, I have a solution for returning the fuel to the tank from which it came, but it does involve teeing the two return pipes together and my concern is that the engine that isn't running will have pressure from the return of the running engine acting on it's outlet port. The return pipe could be pushing the returning fuel a couple of metres up hill to the day tank which I guess is the defining/maximum issue pressure wise, and if I've done my sums correctly a 2m head (of water, I guess fuel will be a tad less) will give 200 mil bars pressure. If the output pump can handle 200 mil bar when not running then I guess I've answer my own question but would appreciate the views of more knowledgeable filk

 

[rogerthebodger]

I had a similar problem with my 3 diesel tanks to a single engine. I piggybacked 2 3 way fuel valves so in switching the supply from one of the tanks the valve set also switched the return to the same tank.