Fuel Polishing/Oil Polishing?

Status
Not open for further replies.
Joined
Oct 31, 2013
Messages
1,551
Location
Georgia
Long term storage of diesel fuel requires the periodic polishing of the fuel to remove water, dead critters (assuming biocide use) and other contaminants. One way of accomplishing that is via a centrifuge from the likes of Alfa Laval, Mitsubishi and a few others. Some engine manufacturers, Cummins and Scania to name two, have options for centrifuges of a sort mounted right on the engines to handle the lubricating oil. Question (and I know it's pretty weak) - when used on the lubricating oil what would you think the risk would be of spinning out some additives using such an approach? The easy answer is that it must be pretty small or two respected engine manufacturers would not be using them. But I'm just looking for you guy's opinion.
 
Last edited:
Originally Posted by DeepFriar
...when used on the lubricating oil what would you think the risk would be of spinning out some additives using such an approach?


None.

Centrifuging is mainly for separating out solids of heaver mass such as soot.
 
Originally Posted by MolaKule
Originally Posted by DeepFriar
...when used on the lubricating oil what would you think the risk would be of spinning out some additives using such an approach?


None.


That's the truth.

Some folks have also wondered if sub-micronic bypass oil filtration (like the Frantz) would scrub out the additives....
the answer to that is also "no".
 
Agree that it's none.

In my turbine days, the centrifuges had a water seal...the varnish, being polar was happier being in the water seal than in the bulk oil so headed that way. The centrifuge was unable to separate that component and clagged up badly.
 
Thanks very much guys for responding to such an elementary question. I'm actually "designing" a 2500 gallon diesel fuel "system" for 2-5 year storage at a remote vacation lodge compound location. While a use schedule would be generated to roll over the quantity in a two year period I'm just looking at the possibility that it won't be and looking at the extremes. The property is mountainous and below adjacent ridgelines so solar is not under consideration at this time. It's offgrid by about a mile and a half as the crow-does-not-fly and for which the power/utilities guys will gleefully charge me $15 A FOOT to bring in utilities. There will be two John Deere 4045 powered three-phase generators of about 40-45 Kw each. There may have to be a load bank because infrequent, variable (mostly lightly loaded) use may cause wet stacking. Obviously efficiency will suffer, I know. That is one of the reasons why I was considering filtration methods for lubrication also. initial running in, cold starts, light loads, high(er) wear. The other potential problem is settling out of additive, if that's a real thing as in oil bottles, so how much "agitation" may be needed over, say, three month, maybe longer, periods of inactivity? That "settling out" was what got me wondering about the possible slinging out of those additives in a centrifuge. Glad to hear it's not a significant worry and thank you again for helping out the dangerous, uneducated boy engineer inside me. ...

Larry
 
Just so you don't chop my head off for misposting that item, I came to you guys in this forum because this diesel/oil storage problem has been, in my experience, most often found in recreational boating. It's also where I became aware, if not familiar, with Alfa Laval. So apologies for the post location but that was my "reason why". Also, the property is lake located and there *are* diesel outboards in the future. .... OK that's a reach... J/K. ...

Larry
 
If you are concerned about some additive fallout over long intervals, drain the lubricant from the bottom center of the oil drum and let gravity do its job. Or take a battery powered drill with a stirrer on the end of a shaft.

I don't think you're going to see much dropout, if any.
 
Thanks Mola. Stir rather than spin or allied with time-based changes seems like the way forward to not worrying about fallout. These engines generally ask for 250 hour changes but a lot of that has to do with hot stacking soot, etc. Would probably (?) be best to follow that 250 or a six month change I'm guessing.

Cheers and thanks again

Larry
 
Quote
That "settling out" was what got me wondering about the possible slinging out of those additives in a centrifuge.


To give a real-world example, on another forum I frequent (boating), a user installed a centrifuge to treat the lube oil in his diesels. He regular checks with laboratory oil analysis. Other than topping up, he has not changed his centrifuged lube oil since 2011. This came up during a discussion of bypass and centrifugal filtration about a month ago.

His boat is a converted 83' Wheeler auxiliary from WWII (used as USN auxulliaries and later USCG cutters). I don't know what it's running exactly for engines since it's been repowered (I believe those were originally Sterling gas engines in WWII). Another growing application of centrigual filtering is in fueling big yachts (super and mega yachts). Taking diesel onboard in dodgy, distant locales drives the need to filter it before it even hitting the main tanks. Centrifuging the fuel pre-tank is now becoming a more common practice.

So these applications are out there, and you can probably look at marine and industrial uses to get real-world examples of how the systems are laid out.
 
Thanks Oro. I see what you mean. Since diesels got *complicated* the biggest single point of failure, in my view, is indeed the fuel. Where older diesels, mechanical injectors for instance, were more tolerant of dirtier fuel the new ones absolutely are not. Most of the trawlers I am familiar with have four layers of filtration (2 Racor and 2 media) even without the Alfa Laval. The last user of even unit injectors, Scania, which are semi-tolerant seems to be going to full electronic.

On the matter of the lube oil centrifuges I have seen literature from Cummins that said using their optional centrifuge system (and other provisions) would yield 20,000 hour service intervals (!). Bear in mind that is adding new lube as it is consumed while likely in continuous duty so the additives, I assume, are getting refreshed and the cold/hot cycle is minimized. I hope the guy you are referencing has a similar scheme to keep additive protection.

Larry
 
If I may return to this one more (last) time... So some additives may settle out of suspension over time but can not be spun out by a centrifuge? Just ask'n.

Cheers and thanks.
 
Quote
I hope the guy you are referencing has a similar scheme to keep additive protection.


Yes - second line of defense (first being the centrifuge) was sample testing, and it was apparently not showing additive depletion/loss.
 
Last edited:
Status
Not open for further replies.
Back
Top