Bypass centrifugal filter
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Delfin
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I didn't Ted, as I don't know much of anything about them. I'm not sure they would have a centrifuge small enough for a 33 hp diesel though. I do know that Cummins goes for removal of all soot, and their use of filter media in the rotor is likely part of that. Their white paper on bypass filtration states that particles as small as .03 microns can be filtered by their equipment, and that is really, really tiny. Since that is well under the fluid film thickness and tolerances of all the parts I can think of in an engine, that seems like overkill but perhaps they are after long term build up of carbon.
Delfin, I'm curious, are you conducting oil analysis? Some evidence suggests that certain additives can be removed by extreme filtration. For anyone who does oil analysis, whether or not bypass filtration is used, I recommend taking a reference sample, that is analyzing a sample of new, unused oil, to which later samples are compared. If additives were being removed, the reference sample would allow you to identify this.
An excerpt from an article on the subject, "The lubricant supplier said that additive suppliers indicate using filters down to a 3-micron size in hydraulic fluid
and wind turbine gear oil applications should remove particulates without leading to additive removal. But use of filters below 3 microns can cause problems. The lubricant supplier says, “We often hear that defoamers may be the first
additive to be removed from a lubricant if filters that are less
than 3 microns are used in a specific system.”
Another article on the subject https://www.machinerylubrication.com/Read/30566/defoamant-additives-filtered
Probably more of an issue with splash lubrication, as in gearboxes, but still worth monitoring in crankcase oils that are uber-filtered.
It seems defoamants are the most vulnerable to extreme filtration.
For those who are interested, an article on oil analysis http://stevedmarineconsulting.com/wp-content/uploads/2014/03/FluidAnalysis143_Final.pdf
An excerpt from an article on the subject, "The lubricant supplier said that additive suppliers indicate using filters down to a 3-micron size in hydraulic fluid
and wind turbine gear oil applications should remove particulates without leading to additive removal. But use of filters below 3 microns can cause problems. The lubricant supplier says, “We often hear that defoamers may be the first
additive to be removed from a lubricant if filters that are less
than 3 microns are used in a specific system.”
Another article on the subject https://www.machinerylubrication.com/Read/30566/defoamant-additives-filtered
Probably more of an issue with splash lubrication, as in gearboxes, but still worth monitoring in crankcase oils that are uber-filtered.
It seems defoamants are the most vulnerable to extreme filtration.
For those who are interested, an article on oil analysis http://stevedmarineconsulting.com/wp-content/uploads/2014/03/FluidAnalysis143_Final.pdf
Delfin, so are you saying that you run this big genset no more than about a 100 hours per year?
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Delfin
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Very interesting Steve, I hadn't heard about potential issues with defoaming agents being filtered out. Assuming I am interpreting this correctly, in looking at the chart in the Machinery Lubrication article, it seems like it isn't a risk unless the viscosity of the oil is greater than something around 70 at 170 degree oil temperatures. That isn't going to happen, so it looks like the risk is pretty low. It also sounds like soot can reduce the effectiveness of the defoaming agents, which argues for better filtration, so I'm not sure how to sort that out.
And yes, I do oil analysis, and on the CAT with the bypass filter, Silicon at the last test was 1 ppm, which is what is used in the defoaming agents. I focus on elements contributing to wear, and for Silver, Aluminum, Chromium, Nickle, Vanadium and Titanium, there are 0 ppm of these elements at a 200 hour sample, so it seems to be working. Soot is 2 ppm, which I think is also low.
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Delfin
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It's been about that but will be going up now that I am retired. I installed additional chargers for the LFP bank, so it will run less than it would otherwise, since we only use the genset to charge batteries when at anchor and to provide additional flow for the thrusters via an auxiliary pump on the genset. The genset uses about $50 worth of oil (Rotella T6) per oil change.
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Delfin
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FWIW, but I checked the centrifuge of the bypass filter on the genset I installed today. With only 13 hours, I was pretty amazed at how much carbon was in the bowl. I really didn't think there would be much after such a short run, but I'm pretty impressed with how well it seems to be working.
Delfin, was the oil new with the filter installation, or did it already have hours on it?
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Delfin
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It was fresh oil, so I assume the centrifuge is picking up left over carbon from whatever oil didn't get drained. I should have taken a picture, but you could scrape your fingernail across the surface of the centrifuge and see the visible residue.
Interesting and not surprising, my experience with centrifuges is they keep oil visibly cleaner, which is backed up in oil analysis reports.
Commander Nomad
Veteran Member
Fwiw, I have a 20kw 1800rpm Onan and struggle to load it past 50%. I just do the best I can and don't worry about it. A very small amount of gray smoke until it gets warm, otherwise it shows no signs of trouble. 7,000hrs on it so far.
North Baltic sea
Guru
Hi,
Can you answer why all ship diesel engines use head filters just centrifugal filters and not spin off filters if they do not give any added value to the engine?
To my knowledge, they are the best way to filter oil.
NBs
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Delfin
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Given the relative simplicity of installation and relatively low cost of the units, installing a centrifuge type bypass filter that has no further operating costs associated with it seems like kind of a no brainer to me. In the world of costs associated with maintaining a boat, this expense is pretty trivial. If I hadn't already installed a Puradyn on the CAT, I would definitely install one of these units on it.
The do work, they have been scientifically proven (I quoted one of the Department of Energy tests in the article I shared previously). However, in addition to actually working well, the reason they are used aboard seagoing ships is to eliminate the need for carrying replacement elements, with a centrifuge you never run out of "filters".
Ski in NC
Technical Guru
Ship engines are a good bit different. Not my field, but I do know some of their systems. Crankcase and crosshead lube is separate from piston/liner lube. It does not get much if any contamination from combustion. I think piston/liner lube is mostly total loss where lube is injected in various points and then lost out the scavenging process. Sump oil runs through centrifuges and I don't think it is changed on schedule like our little engines. They sample it and if ok, it is probably run for years.
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Delfin
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Handling a screw on filter for a 100,000 HP Wartsila might also be a bit awkward.
Not to mention the disposal fees.
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"Handling a screw on filter for a 100,000 HP Wartsila might also be a bit awkward. Not to mention the disposal fees."
What a strap wrench !
What a strap wrench !
Wow not even similar in nature - an extremest comparison...
... of course the best approach to oil purification would be for everyone to just scrap their engines and switch over to Jimmy 6-71’s
