Gravity Fuel Feed to Diesel Engine from Day Tank

[davva]

I have read that NFPA 110 prohibits the gravity feeding of fuel to a prime mover, except from an integral tank. I do not have a copy of the NFPA 110 so I do not know the full reasonings for this?

Due to the size of the engine we are intending to use a separate day tank. In this case is it possible to do away with a feed pump and solely rely upon gravity flow feed to the engine.

If this is possible are there minimum requirements for the pressure head of the gravity flow?

 

[powerwagon75]

davva,

The day tank should not be gravity fed to the genset fuel inlet for reasons of potential leak-through of fuel on the engine if a soleniod or other device was not holding fuel back cleanly at shut-down, as it should. You should not need to add external pump to get fuel from the day tank to the engine.

Diesel engines are equipped with on-board fuel transfer (aka lift) pumps that move the fuel from a local tank to the injection pump. These pumps are more than adequate to "lift" fuel from a local day tank, to the engine. A float & controller system on the day tank would operate a separate transfer pump, to get fuel from a remote bulk storage to the day tank.

You did not mention what size/how old the engine in question is. I know in the old "glory days" of diesel engined power plants, with large, slow-speed diesels, there were applications where day tanks were mounted on stands to keep a positive head to the engine. I don't believe there are any modern diesels that would need this requirement.

Engines that are running integral (very small) tanks with positve head pressure, mounted on the engine, are used to keep back drainage from causing excessive surging at start up as the air is purged out.

eric