Theoritical discussion on diesel fuel centrifuge

[great white]

Here's a thought I recently had that's mostly theoretical:

The "veggie guys" use a centrifuge to "polish" their fuel down to less than one micron. Aparently, it takes a couple passes also.

So, why couldn't a fellow install a 40-80 PSI pump and centrifuge system on our diesel truck to filter out impurities in the tank?

It would run while the truck ran and just go about it's business removing stuff from the fuel. Pull fuel out, spin it up, bits spin out, send the fuel back to the tank clean as a whistle. keep on filtering it until the truck is shut off.

It would have to be an independent circuit from the lift pump circuit, pulling fuel out of the tank and returning it filtered. May not work because of diesel foaming in the return.

I think it would make life a lot easier/longer on those media filters we all have installed in line, and would only require the occasional crawl under the truck to clean out the centrifuge.

Just something to think about and open for discussion.....

 

[Burning oil]

It would work very well if you could pre fuge the diesel before filling up. Ive thought about doing something like that, but chose not to do "onboard" because of expense and how many passes would the fuge make before it was time to fill the tank again?
Filters are cheap and do the job.

 

[great white]

well, lets see:

Suppose a 60 gph 'fuge.

tank is 34 gallons (I think).

So, unless my math is wrong, a pump pushing a 'fuge at 60 GPH will take 34 minutes to make one pass.

Two passes in just over an hour.

If you're bopping around town all the time, probably limited benefit. But still some benefit.

If you're doing any significant highway miles, slightly different story....

Now, filters and cost recovery:

Figure 30-40 bucks a filter. If you have a secondary filter you can double that. (filters are a bit more expensive around these parts).

A decent setup for pump, 'fuge and lines could be somewhere around 300-400 bucks total (if you build it yourself).

So, in theory, if you double filter life (could be almost indefinite if a 'fuge could be made to actually get the tank of diesel down to <1 micron), after 4 missed filter changes it's potentially paid for itself.

I'm guessing somewhere around 50,000 miles to recoup cost, if it works as suspected.

But that's a lot of "if's".......

Feel free to discuss and poke holes in that theory......:thumbsup:

 

[ak diesel driver]

my filter hasn't been changed in at least 2 yrs. We have pretty clean fuel around here and that's probably around 50k of driving.

 

[bison]

Pushing that fuel around at that rate will prob cause it to foam worse than soap in the bath tub+ dont you think we got enough pumps allready on these trucks that can fail.

I have'nt changed a fuel filter in yrs,but then i got clean fuel from my farm bulk tank.
i hardly if ever fill up along the road.

 

[Turbine Doc]

When I was USN "oil king" we used to polish fuel two ways, centrifuge, and recirc across filter media, rather than a fuge you could polish via recirc, across a 2 mic filter suction/return to the tank, also known as stripping it.

That said with a 30 micron primary and 5 mic nominal final our fuel is pretty clean. I'm with Bison probably overkill, my last primary filter change for me lasted 3 years, the final on engine was over 4 years old, I changed them last Sept. just because I was making a long distance trip to Erie PA from MS and was gonna be there a month, and I was getting intermittent vac alarms on hard WOT acceleration.

 

[Franko914]

Pushing that fuel around at that rate will prob cause it to foam worse than soap in the bath tub+ dont you think we got enough pumps allready on these trucks that can fail.

I have'nt changed a fuel filter in yrs,but then i got clean fuel from my farm bulk tank.
i hardly if ever fill up along the road.

The centrifuge will eliminate foam because of the G forces involved in the centrifuge process. Nevertheless, I also think this step is overkill when regular filters can do just a good a job.

 

[Matt Bachand]

I like the idea GW. Could you tap the main lift pump input fuel line to a branch of the super clean fuel with a pressure reducer of some sort so the fuel that the lift pump pulls is ONLY the super clean fuel, and the rest will go back to the tank and continue to polish the fuel.

There should be plenty of time during the wait to start for the centrifuge to start, and the clean draw be pressurized. In fact, it may help lift pump pressure if its somewhat pressurized instead of the lift pump having to pull.

I have no idea how to reduce pressure in liquid form, I assume a regulator of some sort is available similar to air?

 

[Franko914]

<snip>...I have no idea how to reduce pressure in liquid form, I assume a regulator of some sort is available similar to air?

Hey Matt,

Orifice, orifice, orifice. Bypass oil filters use an orifice (~1/16") to tap the oil line. LP and natural gas regulators use an orifice, too. Has to be clean/smooth (numbered drill bit, bench drill press, drill press vise, cutting oil).