What is beta ratio?

[another Todd]

On the Wix filter site I am looking at three different filters for my Cat 3176 engines. They are identified as follows:

51792-standard filter
Beta ratio(BR)---2/20=8/21
Nominal Micro Rating (NMR)---19

51792XE-synthetic media version of above
BR---2/20=3/10
NMR---5

51792XD-extended drain version
BR---B2=5
NMR---5

What is a beta ratio and what do the numbers mean, and how do they compare to each other?

What is a Nominal Micro Rating, and again, what do the numbers mean, and how do they compare to each other? Thanks.

 

[Gary Allan]

Only the 5179XD "matches".

B2=5 means that 1 out of 2 particles 5um or higher are filtered in their test.

B(#) #-1/#=% of filtering

B75=10 would be 74/75% of the 10um (or higher) particles.

Beta20=10 would be 95% of the 10um particles (or higher) 19/20=95%

I'd throw out the NMR on the top two (the last spec).

Beta 2 is nominal (50%).

 

[another Todd]

Gary Allan, thanks, but it's still greek to me. I am not following you. Are these (Beta Ratio & NMR) explained in detail somewhere? Which filter would you buy? 51792 is $15.31. XE is $24. XD is $36 and are any of these numbers greatly better than the others?

 

[Vilan]

A beta ratio of X means that for every X particles that enter the filter, 1 of them goes through and the rest are stopped by the filter.

Let's look at the one you mentioned.

"Beta ratio(BR)---2/20=8/21"

The 2/20 part is the beta rating, the 8/21 is the corresponding micron particle size for that rating. So there is a beta ratio of 2 for 8 micron particles, and a beta ratio of 20 for 21 micron particles.

For 8 micron particles, beta is 2, so 1 out of every 2 of them escapes the filter. For 21 micron particles, beta is 20, so 1 out of every 20 escapes. By "escape" I mean it gets missed by the filter and keeps circulating in your engine.

Now the synthetic version:

"BR---2/20=3/10"

This one has a beta ratio of 2 for 3 micron particles, and beta of 20 for 10 micron particles. This is better than the non-synthetic version... that one filtered out half of the 8 micron particles, but the synethic one can filter out half of the 3 micron particles, which are smaller, so that tells you it has finer filtration. Whether that is really meaningful in terms of how long your engine will last, though, I'm not so sure.

 

[another Todd]

Thank you. I have been studying this subject through the search feature. I understand it now. Looks like I am buying the synthetic one. Thanks

 

[carock]

I have been conducting my own beta tests on filters, I am still trying to get it to work consistently. The beta ratios are influenced to a LARGE degree by the exact conditions of the test. This makes me wonder how valid the advertised beta ratios are.

 

[Gary Allan]

If you're still in the dark after Vilan's post here ..let me try agian. It's not rocket science ..but it sure is an odd form of notation until you get your vision straight.

the Beta number is a number that will always work out to a %.

Beta2 is 1/2 ...or 50%
Beta3 is 2/3 ...or 66.6%
Beta4 is 3/4 ..or 75%
Beta5 is 4/5 ..or 80%
Beat6 is 5/6 ..or 83.3%
Beta75 is 74/75 or 98.6%
Beta1000 is 999/1000 or 99.9%

beta number minus 1/(over) beta number = the efficiency at (?) that particle size.

So, beta2=10 is 1/2=50% of 10um particles are filtered (or not, as Vilan terms it).


You'll probably never see 3-6 unless the rating is for a specific sized particle.

Most of our automotive filters are rated at NMR (nominal micron rating) and either 95% or 98.5%

Nominal is Beta2 (1/2=50%)

51792XE-synthetic media version of above
BR---2/20=3/10
NMR---5

If all of these filters are the same size ..and assuming (bad practice, I know) that the media has the same holding capacity and whatnot, I don't see how one can be an extended drain filter over the other ...especially if they're that close in levels of filtration.

I'd go with the $24 one.

 

[Filter guy]

This tech bulletin explains beta ratios..

http://www.filtercouncil.org/techdata/tsbs/89-5R3.pdf

There is also a "newer" Beta test, that is expressed as B10(c)=200

(c) would indicate the filter was run under the new ISO test procedures. Without the (c), it was run to the old SAE or ISO test.