Originally Posted By: oil_film_movies
Originally Posted By: dnewton3
Where do some of you get these ridiculous ideas, anyway?
Its OK to question if something with great efficiency has too high of a flow resistance. Thats not a stupid question.
Intuitively, you might think a filter is more restrictive the smaller the flow path porosity is.
Flow any liquid into a smaller pipe and you'll see the pressure drop go up, of course.
In this case, the Fram Ultra isn't too restrictive at all. It can hold more dirt than most other filters.
The physical reality of smaller, more consistently sized synthetic fibers is what makes the Ultra work.
Now superimpose one picture over another and you have synthetic blend. The advantage of cellulose is it's wood cell structure can hold finer particles and even water molecules. Synthetic fibers don't do that, they depend on the gaps between the fibers to hold particles. Those fat wood fibers are a good thing. I think they can act like mini bypass filters.
people say to that.
I think the concerns over a 80% 5 micron claim are justified, seems too good for a full flow to not clog. But the Ultra uses two layers of media to get flow with capacity and fineness. The other synthetics except Champ Labs seem to have higher multi pass numbers and they are single layer. I think the Fram testing can be relied on to make the bypass valve open correctly and the flow rates adequate within capacity. Still many unknowns, partly because companies don't tell much. Like capacity, there is a difference between 20 grams of fine dust and 20 grams of pebbles as to when they clog a filter.
Originally Posted By: dnewton3
Where do some of you get these ridiculous ideas, anyway?
Its OK to question if something with great efficiency has too high of a flow resistance. Thats not a stupid question.
Intuitively, you might think a filter is more restrictive the smaller the flow path porosity is.
Flow any liquid into a smaller pipe and you'll see the pressure drop go up, of course.
In this case, the Fram Ultra isn't too restrictive at all. It can hold more dirt than most other filters.
The physical reality of smaller, more consistently sized synthetic fibers is what makes the Ultra work.
Now superimpose one picture over another and you have synthetic blend. The advantage of cellulose is it's wood cell structure can hold finer particles and even water molecules. Synthetic fibers don't do that, they depend on the gaps between the fibers to hold particles. Those fat wood fibers are a good thing. I think they can act like mini bypass filters.
I think the concerns over a 80% 5 micron claim are justified, seems too good for a full flow to not clog. But the Ultra uses two layers of media to get flow with capacity and fineness. The other synthetics except Champ Labs seem to have higher multi pass numbers and they are single layer. I think the Fram testing can be relied on to make the bypass valve open correctly and the flow rates adequate within capacity. Still many unknowns, partly because companies don't tell much. Like capacity, there is a difference between 20 grams of fine dust and 20 grams of pebbles as to when they clog a filter.
