Buoyancy float - diesel tank
Buoyancy float - diesel tank
(OP)
I'm a Mech Eng seeking a suitable material(s) as a small (45mm OD) cylindrically shaped flotation device for use in diesel fuel tanks. To date, I have looked at extruded closed cell polyethylene (PE) foam or machined billet PE (hollow). I have in my mind a low S.G. foam - preferably hard setting - that can be machined, extruded, cut, or otherwise formed into the desired shape. A suitable material must have a low S.G., be compatible with diesel fuel, and NOT absorb the diesel. These points will ensure the buoyancy force is maximised (per unit volume).
I'd appreciate any assistance you can provide. Kind Regards.
I'd appreciate any assistance you can provide. Kind Regards.





RE: Buoyancy float - diesel tank
You should be able to eliminate the diesel absorbtion by dipping the foam into epoxy resin, so giving it a diesel proof coating.
Plastic floats for petrol carburettors are usually hollow mouldings of nylon, polyester, or acetal.
These are usually moulded in pieces and welded together.
Tooling costs could be many thousands of US dollars.
It might be possible to extrude any of these materials as foam, but wether or not they will be closed cell foams, I couldn't say. The high surface area of foams makes them more susceptible to absorbtion and permeation, when compared to a hollow moulding of the same weight.
Regards
pat
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RE: Buoyancy float - diesel tank
RE: Buoyancy float - diesel tank
What I had in my mind was a hard setting "closed" foam (low S.G.) that could be formed/machined/extruded into the required shape. I've seen something at some stage in the past, but am buggered if I can think what it is.
What makes it more difficult is that diesel is not the most benign substance going 'round.
Cheers
RE: Buoyancy float - diesel tank
The treat blow moulded PE fuel tanks and fuel drums with fluorine to improve the permiation to acceptable levels.
Rotational moulding uses very little pressure, so there might be porosity in the mouldings as well as permiability problems. Fluorine will not fix porosity.
I suggest any easy to work,low density foam, dip coated with a resin known to have good barrier properties to the diesel fuels.
You might consider making a prototype shape, then making cheap moulds from wood, fibreglass or even plaster of paris, then useing two pot self foaming polyurethane, then dip coating.
Regards
pat
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Buoyancy float - diesel tank
SG 0.24 solid or 0.16 ground.
RE: Buoyancy float - diesel tank
I never thought of cork. I expect that it would need to be dipped in a resin to seal it.
Regards
pat
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Buoyancy float - diesel tank
RE: Buoyancy float - diesel tank
RE: Buoyancy float - diesel tank
It's cheap, it can be machined, and you can weld it (ultrasonic / laser?) but I don't know if you can get it as foam.
I believe it's impervious to diesel but check with a supplier