Fuel Polishing - Why and how

[veggie]

With winter approaching we should be thinking about our emergency generators and the associated systems.

I understand that fuel stored for a standby generator should be "polished" from time to time.
I would like to build a polisher for my large tank and I do have a 12 volt gear pump and a few filter heads which can accept spin-on elements of various micron ratings.

What is the reason for the polishing and what is typically the proper way to do it?
How often ? .... What micron filter? .... How many passes ?

cheers
veggie

[mobile_bob]

1 micron is more than adequate, and a single pass is also enough in my opinion

if you add a fuel conditioner or additive it ought to be good to use for quite a long time.

my npr isuzu has set for years, once for over 6 years, never did a thing to the fuel, just put in a fresh
set of batteries and started the old girl up... and never missed a beat.

it has set now for over 4 years, and i would bet it will start up and run just fine with another set of batteries.

fuel polishing and all the fuss is probably more important with electronic injection system, such as the HUI systems typical of
cat, navistar and the GM duramax engine's, along with other more expensive modern diesels.

for a changfa or lister or their 'oids i can't imagine having a problem storing fuel for these engine's

of course keeping the condensation down, which means draining the bottom of the tank, a dose of conditioner/algicide (sp)_is probably more than these engine's get in a large segment of the world.

not sure if this is helpful?

bob g

[Dualfuel]

 Dear veggie, polishing is good when your fuel was made in the summer and the oil is mixed with lard or other oils whose Gel point is in the 50s. When the fuel tank cools down, the hi gel point fuel condenses all of the fuel tank. This sometimes can't get into the filter and plug it up for no good reason. Another reason for polishing is if the fuel tank is open to the atmosphere, the fuel will begin to polymerize, which means it starts to dry like paint on the walls of the fuel tank. Polymerized fuel will plug a filter very quickly. By keeping it stirred up and polished you remove both the hi gel point particles, and the polymerized fuels.

[Jens]

I found that if your fuel is veg oil based, a filtering run once a year is pretty much required. Even in sealed tanks, I would get a layer on the bottom of polymerized product and that can plug up a filter in a matter of minutes (if you are picking up from that layer).
Another way of dealing with the issue - pick up fuel from higher up in the tank and then, when time allows, re-process the left over veg oil with incoming new oil to filter out contaminants.
Yes, some higher melting point product can gel up but the easiest way around that is to have the fuel filter next to the warm engine. Ofd course one assumes that your fuel stock itself is not sitting at -30C