What Does "Nominal" Micron Rating Mean?

[garageman402]

Maybe this has been covered, but I couldn't find it. I'm looking at a Baldwin B7449 oil filter with 9.8 nominal, 27 absolute micron rating. How would that compare to a percentage of a specific micron?

Thanks

 

[fantastic]

Maybe this has been covered, but I couldn't find it. I'm looking at a Baldwin B7449 oil filter with 9.8 nominal, 27 absolute micron rating. How would that compare to a percentage of a specific micron?

Thanks

Depends on who you ask...

Fleet filter.com says:
1. Nominal Micron Rating means that the filter can capture a given percentage of particles of the stated size. For example, a nominal micron rating of 10 microns at 95% means that the filter media retains 95% of the particles that are 10 microns and larger.
2. Absolute Micron Rating means that the filter is tested using a single pass of contaminants through a filter media and any particles that pass through are measured.You could end up with a 96.7% retention of that micron number.

Ecogard says:
Nominal Micron Rating expresses the ability of the filter to capture particles of a specified size in microns at an efficiency of 50%. A nominal rating of 50% at 10 microns simply means that a filter captures 50% of contaminants 10 microns in size. The statement of this efficiency is important to understanding the performance capability of the filter.

https://ecogard.com/resources/articles/truth-about-oil-filter-micron-ratings/

Fleetguard says: Nonsense
Micron rating is the size of particles which are filtered out by filters at a certain efficiency. When this efficiency is at least 98.6%, we speak about absolute micron rating/filtration. Nominal micron rating is just a commercial trick for all efficiencies lower than 98.6%. For example, even if a filter has a nominal rating of 10 microns, not all particles that size will be captured in the filter.

I think what they are saying is that a company that advertises a "nominal" rating it can display a very small particle size to make it appear efficient. While an absolute rating is the real deal where most of a particular particle will be filtered out. I do feel a percentage at x microns can still be useful information.

 

[garageman402]

Thanks, fantastic, for the info, the link was especially helpful!!

 

[ZeeOSix]

Maybe this has been covered, but I couldn't find it. I'm looking at a Baldwin B7449 oil filter with 9.8 nominal, 27 absolute micron rating. How would that compare to a percentage of a specific micron?

Thanks

Regardless of what definition of "nominal" efficiency is used, the efficiency in this case would have be pretty low at 9.8 microns if it's 27 microns "absolute" efficiency. In this case I'd say Baldwin is using "nominal" as 50%.

 

[ZeeOSix]

Fleetguard says: Nonsense
Nominal micron rating is just a commercial trick for all efficiencies lower than 98.6%. For example, even if a filter has a nominal rating of 10 microns, not all particles that size will be captured in the filter.

If the term "nominal efficiency" was that loose and undefined, the term shouldn't even be used. Per Fleetguard even a hair less efficiency than "absolute" could be defined as "nominal". So why even have a term like that - ie, 95% @ 20u or even 5% @ 20u could be called "nominal" efficiency per Fleetguard, which is a useless way to describe efficiency. Think most filter makers who use the term mean 50% efficiency, like the EcoGard explanation.

 

[fantastic]

If the term "nominal efficiency" was that loose and undefined, the term shouldn't even be used. Per Fleetguard even a hair less efficiency than "absolute" could be defined as "nominal". So why even have a term like that - ie, 95% @ 20u or even 5% @ 20u could be called "nominal" efficiency per Fleetguard, which is a useless way to describe efficiency. Think most filter makers who use the term mean 50% efficiency, like the EcoGard explanation.

Nominal doesn't seem to be defined at a set efficiency below the rule defined Absolute efficiency. 50% is not the only way to display nominal & companies take advantage of showing a smaller micron rating to seem "efficient" when they may not be. I think FG is stating what they've seen about that type of marketing. There is no set rule outside of stated efficiency below absolute. I do think 50% @x micron can still be useful but it's not the only way companies advertise nominal unfortunately. That's kind of the problem. If everyone was playing by the same rules like Ecogard states then it would be great but they're not so you must use Absolute to have the rule standard. All filter companies should test & state every single filter's Absolute efficiencies but we can't even get that. All that being said Fleetguard does a better job than Ecogard on that front. Ironically, I don't think Ecogard even display 50% efficiencies.

 

[Fair enough]

IMO it doesn’t amount to anything. In the end the modern engine runs pretty clean, some engines very clean. The particles are not being generated in the large concentrations that are used in all these tests. We see some highly touted oil filters like Toyo Roki without factory ratings. But the media is full of holes. The only way I personally can conclude is Toyo doesn’t know what they are doing, or when the concentration is very low in particles the efficiency changes.
If you take a truck full of particles and dump them on the filter media, many will get through, as many as the holes are. If you take five particles and dump them on the media maybe none get through, probably none. The particles have to be damaging particles, which makes them even less concentrated.

 

[kschachn]

IMO it doesn’t amount to anything. In the end the modern engine runs pretty clean, some engines very clean. The particles are not being generated in the large concentrations that are used in all these tests. We see some highly touted oil filters like Toyo Roki without factory ratings. But the media is full of holes. The only way I personally can conclude is Toyo doesn’t know what they are doing, or when the concentration is very low in particles the efficiency changes.
If you take a truck full of particles and dump them on the filter media, many will get through, as many as the holes are. If you take five particles and dump them on the media maybe none get through, probably none. The particles have to be damaging particles, which makes them even less concentrated.

Full of holes you say?

 

[garageman402]

Regardless of what definition of "nominal" efficiency is used, the efficiency in this case would have be pretty low at 9.8 microns if it's 27 microns "absolute" efficiency. In this case I'd say Baldwin is using "nominal" as 50%.

The comparable Donaldson has a nominal rating of 6, I think absolute is 25?

 

[ZeeOSix]

The comparable Donaldson has a nominal rating of 6, I think absolute is 25?

Looks like they are using the same "undefined" definition of "nominal", and not using a dart board to come up with a "nominal" efficiency.

 

[ZeeOSix]

https://precisionlubrication.com/articles/oil-filter-efficiency

Nominal
While there are some definitions of nominal in the filtration world, when it comes to oil filters, a nominal rating often means no better than 50% capture efficiency at the specified micron size.

 

[garageman402]

The comparable Donaldson has a nominal rating of 6, I think absolute is 25?

My mistake, Donaldson does not show an absolute value.

https://precisionlubrication.com/articles/oil-filter-efficiency

Nominal
While there are some definitions of nominal in the filtration world, when it comes to oil filters, a nominal rating often means no better than 50% capture efficiency at the specified micron size.

Thanks for that link, in one statement under the "Nominal" heading it was said:

"For example, I was recently asked my opinion on an inline hydraulic filter labeled a 10-micron cellulose filter. Digging deeper, I found that the filter manufacturer reported 95% efficiency at twenty microns but a little more than 50% efficiency at ten microns."

Granted this example was a cellulose filter, the Donaldson synthetic claims a nominal rating of 6 microns. Would it be safe to assume that the absolute value would be close to or better than 20 microns?

In this chart (from the above link) the 25 micron filter appears to be heading toward a 6 micron 50% rating, while it is absolute at around 14-16 microns, can this performance be assumed from the Donaldson 6 micron nominal filter?

 

[ZeeOSix]

My mistake, Donaldson does not show an absolute value.

Donaldson only list a nominal efficiency? Of they have any beta ratio listed? Might want to email or call for more efficiency info and details.

You should email or call Baldwin and ask them that their definition of "nominal efficiency" is.

Thanks for that link, in one statement under the "Nominal" heading it was said:

"For example, I was recently asked my opinion on an inline hydraulic filter labeled a 10-micron cellulose filter. Digging deeper, I found that the filter manufacturer reported 95% efficiency at twenty microns but a little more than 50% efficiency at ten microns."

Granted this example was a cellulose filter, the Donaldson synthetic claims a nominal rating of 6 microns. Would it be safe to assume that the absolute value would be close to or better than 20 microns?

If they define "nominal" at 50% efficiency, then it very well could be close to absolute 98.7-99% at 20u.

In this chart (from the above link) the 25 micron filter appears to be heading toward a 6 micron 50% rating, while it is absolute at around 14-16 microns, can this performance be assumed from the Donaldson 6 micron nominal filter?

Hard to predict for sure based on the efficiency scale only going down to 80%, but the grey curve would seem to basically fit your extrapolated assumption. The OG Ultra per Motorking was 80% @ 5u, so if a line for 20u was drawn in that family of curves, it would look to come in around 80% @ 5u.