STP air filters this bad?

[circuitsmith]

Anybody that understands air filter efficiency ratings would realize that "90%" with no context is meaningless.
Make the dust fine enough and any engine air filter efficiency will fall to 90%.

 

[ZeeOSix]

Originally Posted by circuitsmith
Anybody that understands air filter efficiency ratings would realize that "90%" with no context is meaningless.
Make the dust fine enough and any engine air filter efficiency will fall to 90%.


Anyone "rating" an air filter at "90% efficiency" without any testng reference or at least a corresponding particle size is probably going to be even worse than that if test out to be per ISO 5011. STP (or any other air filter maker) would never use test dust finer than the fine ISO 5011 dust spec to make their filter look bad. In fact, many air filter makers use the optional course dust spec called out in ISO 5011 to make their filter look better in terms of efficiency.

That's why ISO 5011 calls out exactly what the dust composition is for efficiency testing. Have to be able to compare filtering efficiency based on the same testing procedures.

If a filter was actually rated 90% efficient per ISO 5011 then it's not a very good air filter and is letting a lot of dirt go into the engine. If it's just "rated" at 90% with no reference to the dust size then I'd never use that air filter because it could even be worse than 90% if tested per ISO 5011.

 

[wewsnu]

Originally Posted by ZeeOSix
Here's test dust specs for various filter testing.

https://www.particletechnology.com/test-dust

ISO 5011 for air filter testing calls out:

5 Test materials and test conditions
5.1 Test dust
5.1.1 Grade
The test dust to be used shall be ISO 12103 - A2 (ISO Fine) or ISO 12103 - A4 (ISO Coarse), subject
to agreement between the filter manufacturer and client. The chemical analysis and the particle size
distribution shall conform to ISO 12103-1.
In the absence of an agreement on the dust

— for single-stage filters, use ISO Fine test dust, and
— for multistage filters, use ISO Coarse test dust.



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