Converting water tank to fuel tank

[Buck Harrison]

I'm having a new H-420 commissioned (as we speak) at Norton's in Deltaville, Va. I had been told that the aft water tank (approx. 50 gal)could be converted for use as an auxillary fuel tank; but upon further investigation Norton's service manager tells me that the water tank cannot be used as a fuel tank because the fuel and water tanks (while both plastic) are not the same plastic, and the water tank material cannot stand up to diesel fuel.Does anyone have any information (or where to find information) about the differences in these tanks.Will the water tank material REALLY deteriorate if diesel is put in it?

 

[Peggie Hall/Head Mistress]

You cannot do it.

Water and holding tanks are made from linear polyethylene. Plastic fuel tanks MUST be made from crossed-linked polyethylene, which has an entirely different molecular structure. Fuel permeates linear poly very easily, but cross-linked poly is as impervious to permeation by fuel as linear is to permeation by by water and sewage.Plastic fuel tanks must also be made to a strict CG standard: minimum wall thicknesses, all fittings on top, fittings may not be moved once installed, and no surface may be constructed so as to allow liquid to pool on it. So your plastic water fails on all counts.