Do oil filters "cough up" captured contaminants...

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... when the engine is started again?

I came across this PDF a day or two ago (quite possibly linked to by somebody here on BITOG, but I forgot), and on page 6, it describes how particle counts indicate much higher numbers of contaminants in the oil, after a restart.

You can see the document here: https://www.hyprofiltration.com/clientuploads/directory/Products/PDFs/FE-PUB/DFE.pdf

Now my question is--is this related to oil filters for passenger cars? Or is this something that happens only with filters for other engines?

FWIW, I couldn't find any dating information in the text of the file itself, but when I opened the file up in my PDF reader, the file properties said it was created in 2009.
 
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I suppose it's not outrageous that contaminants that are captured behind the filter media, but not in it could come loose and be briefly circulated if the filter bypasses.

Does it actually happen? No idea.
 
Its my understanding of those researchers, that they are talking about this phenomenon happening when the engine restarts, not when the filter goes into bypass mode. I'm not denying you can get dirty oil in bypass mode (depending on the location of the bypass valve)---only clarifying what the document is talking about.
 
Originally Posted By: paulri
Its my understanding of those researchers, that they are talking about this phenomenon happening when the engine restarts, not when the filter goes into bypass mode. I'm not denying you can get dirty oil in bypass mode (depending on the location of the bypass valve)---only clarifying what the document is talking about.

Interesting article. Cold starts create more delta-p across the media due to the thicker oil. Not unreasonable that some captured particles in the media get dislodged by the higher delta-p, especially if there's a short sudden delta-p spike on initial start-up.

Same thing basically happens as an oil filter gets loaded up and the delta-p across it increases with time. That's why the graph by Purolator/M+H shows that the efficiency decreasing with time & loading, until the efficiency shoots up towards the end when it's really getting loaded/clogged and close to the bypass valve setting.

 
Originally Posted By: paulri
Z06, I sent you a pm about that study you linked to.


Got it, this thread might be a good one to expand on the Puro/M+H paper too since it seems somewhat related. Could link the original Puro/M+H paper where my snip-it came from.
 
Originally Posted By: ZeeOSix
Originally Posted By: paulri
Z06, I sent you a pm about that study you linked to.


Got it, this thread might be a good one to expand on the Puro/M+H paper too since it seems somewhat related. Could link the original Puro/M+H paper where my snip-it came from.


That would be great,

seems like a lot of info is missing.
 
actually the paper i linked to in the op is different, with a different thesis so i,ll link to it in another thread when i look up what z06 mentioned in a pm.
 
Synthetic fibers are slick too, nothing sticks and all washes off. Every time the car is started it's like getting a brand new filter. That's why they can last so long.
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Originally Posted By: paulri
actually the paper i linked to in the op is different, with a different thesis so i,ll link to it in another thread when i look up what z06 mentioned in a pm.


The Purolator/M+H paper is somewhat related to the original post link in that captured debris can get forced off the media from delta-p and oil flow.
 
Originally Posted By: goodtimes
Synthetic fibers are slick too, nothing sticks and all washes off. Every time the car is started it's like getting a brand new filter. That's why they can last so long.


The gist of the paper is that it's the media design that ensures solid capture during DFE testing, not necessarily the media material. They talk about their "G8 Dualglass" media (note 'dual') performing better in DFE testing vs other glass media filters. Don't see where they tested any full cellulose media, so can't conclude anything on how they would perform in DFE testing.
 
Sure it happens all the time when you have accumulated bigger particles and debris that only hold against the media with pressure, and probably end case pieces not fully embedded.

That gunk falls to the bottom

-the heaviest of which is right next to the bypass in a dome down bypass down scenario.


UD
 
Originally Posted By: UncleDave

Sure it happens all the time when you have accumulated bigger particles and debris that only hold against the media with pressure, and probably end case pieces not fully embedded.

That gunk falls to the bottom

-the heaviest of which is right next to the bypass in a dome down bypass down scenario.

UD


I think the paper is talking about captured debris being dislodged from the media, not debris that gets swept through a bypass valve. Same kind of debris shedding from the media talked about in the Purolator/M+H paper.
 
Originally Posted By: ZeeOSix
Here's the document where the graph I posted came from: LINK

This is a cut and paste from email traffic between me and Purolator back in 2011. Their study report is dated 2013, so they obviouly knew of this decreasing efficiency with loading because they would see it happen over and over during ISO 4548-12 testing.

============== Start of Email Correspondence ==================

Email #1 with Todd Vick, Purolator Engineer (4/1/2011)

My Questions:
1) When the rating of 99.9% at 20 microns (for the PureONE) or 97.5% @ 20 microns (for the Classic) is shown per ISO 4548-12, is this rating at the beginning of the test when the filter is basically new, somewhere in the middle of the test (averaged), or at the end of the test when the filter's maximum holding capacity is achieved?

2) Does an oil filter's efficiency increase as it becomes loaded with trapped debris? If so, about what is the general percent difference in filtering efficiency of a new filter vs. a filter at maximum debris loading point?

Purolator's Response:
The rating of a filter is the average efficiency during the life of the test. The test is terminated at a predetermined differential pressure across the element. The report writer of the equipment will print a graph which will show typically the filter starting with higher efficiency, dropping slowly and then increase efficiency in the latter part of the test – a “hockey stick” visual effect. The reporting is automatic with the test stand and cannot be adjusted externally.

The efficiency is highest at the beginning (before the media is attacked by oil and acidity) and again at the end as contamination does improve efficiency. We cannot correlate the change of efficiency to predict the change during the lifecycle on a car.

===========================================================

Email #2 with Todd Vick, Purolator Engineer (4/4/2011)

My Questions:
Can you please clarify about the filter's efficiency at the start vs. at the end of the test?

I understand your "hockey stick" shaped efficiency curve. But was wondering if the efficiency at the end of the test can actually be higher than at the start? From what you have described, it sounds like the highest efficiency happens when the filter is new at the start of testing.

Purolator's Response
The test duration is based on filter size and termination differential. For benchmarking, we use 8 psi increase in pressure across the filter as the self-termination point. Based on the size of the filter, media area, media design, the test can run as short as 15 minutes for a small 65mm filter for over 1 day for a class 8 full flow filter. Typically from the graphs I see, efficiency at the end of life is slightly less than a new filter.

The IAM filters that replace an FL1A will test in 1 – 2 hours depending on brand and model.

============== End of Email Correspondence ==================
 
Lot's of good filter information on that hyprofiltration.com website. This is good info on the difference between cellulose and synthetic media - LINK
 
Meanwhile, back at the ranch....

I came across this PDF a day or two ago (quite possibly linked to by somebody here on BITOG, but I forgot), and on page 6, it describes how particle counts indicate much higher numbers of contaminants in the oil, after a restart.

You can see the document here: https://www.hyprofiltration.com/clientuploads/directory/Products/PDFs/FE-PUB/DFE.pdf

Now my question is--is this related to oil filters for passenger cars? Or is this something that happens only with filters for other engines?

FWIW, I couldn't find any dating information in the text of the file itself, but when I opened the file up in my PDF reader, the file properties said it was created in 2009.
 
Interesting that the big uptick is in 4 & 6 micron particles, not 14 micron ones, which (to me) means it is NOT a bypass event, but only caused by the surge of oil through the media on a restart. Considering that cellulose filters aren't rated at sizes that low (at all), and synthetic depth media filters are rated at a low percentage for particles that small-I guess that means, for best results, NEVER SHUT OFF an engine! This may be part of the reason that taxi cabs and other vehicles that are rarely shut off & allowed to cool down seem to have the longest engine life.
 
Originally Posted By: paulri
Meanwhile, back at the ranch....

I came across this PDF a day or two ago (quite possibly linked to by somebody here on BITOG, but I forgot), and on page 6, it describes how particle counts indicate much higher numbers of contaminants in the oil, after a restart.

You can see the document here: https://www.hyprofiltration.com/clientuploads/directory/Products/PDFs/FE-PUB/DFE.pdf

Now my question is--is this related to oil filters for passenger cars? Or is this something that happens only with filters for other engines?

FWIW, I couldn't find any dating information in the text of the file itself, but when I opened the file up in my PDF reader, the file properties said it was created in 2009.

That's the same link you posted at the top of this thread.
Yes, I'd say it applies to all oil filters, but as the paper shows, the level of particle shedding seen in DFE testing is dependant on the design of the media.
 
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