Originally Posted By: goodtimes
Originally Posted By: ZeeOSix
Originally Posted By: goodtimes
Originally Posted By: ZeeOSix
Particle counters are what obtains the upstream and downstream test data to determine an efficiency, so yes it certainty does have to do with the capability of the test equipment. Read ISO 11171 and ISO 4548-12 as already suggested.
Nope, it has only to do with the fact there are too few particles to be significant. According to Fram. Other tests are not relevant either. They are talking about the specific multi pass test for oil filters using the specific test dust. It has nothing to do with equipment, and Fram says nothing about equipment. There are too few particles, that isn't hard to understand.
What Fram is talking about is too few particles for an
inaccurate particle counter to distinguish a low number of particles, thereby losing measurement confidence at the high efficiency end of the spectrum. Again, Fram's paper was 17+ years ago information when particle counters weren't as good as they are today.
Originally Posted By: goodtimes
It isn't that they can't be counted, it's that, for example, if there are 10 particles left and further running shows 9, it means nothing, type of thing. Write to Fram. The whole bulletin is about not falling into the error you are falling into with data. This is like trying to explain why greater than 20 also means 20 in the real world.
It is about them not being able to count low levels of particles accurately
because it's all about the performance and accuracy of the particle counters - it's the only thing that gives numbers to do the efficiency calculations per ISO 4548-12. If you could invent a particle counter that could count every single particle and its size 100% accurately upstream and downstream of the filter, you could measure an efficiency from 0% to 100% with complete accuracy.
If you could count every last particle 100% accurately then every last particle would be significant in the efficiency calculation. If you measured 1,000,000 particles upstream and measured 1,000 particles downstream with 100% complete accuracy, then the beta ratio would be 1,000 (99.9% efficiency).
The confidence of your test results depend on the accuracy and resolution of your test equipment, and the accuracy of the test procedure. That's true for any kind of lab testing.
No, Fram wasn't talking about inaccurate particle counters. What you are trying to believe is they only saw a few particles then, and a new counter would see all the invisible particles they couldn't see, bringing up the particle data to be relevant. That is frankly ridiculous. You add information to make yourself believe you are right. And the other lab test with 2.7 micron(?) particles does not apply to this standardized auto oil filter test.
It's not rediculous if you understand the testing involved, and the basic knowlege about how particle counters work and what their capabilities are. If you would have read what I suggested you might have put the pieces together. Some critical thinking is required at times to see beyond what a few sentences written 17 years ago is trying to convey.
As said before, the particle counter performance has everything to do with the accuracy and resolution of the measured efficiency. What else does the counting for the calculations - it's not "particle fairies" doing the counting. We'll just have to agree to disagree because a broken record get old.