quote:
According to Dr.Cantor at STLE, Amsoil says they can get oil flow through this media to 2C. cellulistic filter media WILL bypass at 10C.
I'm interested in if this assertion from Dr. Cantor is indexed for a given fluid viscosity. I'd really like to understand the conditions that the statement was relating to.
All of my empirical observations have been that, as long as no pump relief action is employed, the filter is merely a minor component in a series circuit. It always maintains a proportional ratio between it and the engine ..with the engine producing the lion's share of the resistance. When I have any viscosity fluid that doesn't produce peak pressure, the typical max PSID is about 2PSID (for example 82/80) cold. As the oil warms ..the difference will be lower ..but will progress as the filter loads. So with a loaded filter ..that PSID figure will rise with the engine back pressure ..and in relationship to it.
I've yet to detect/observe a reactive component to this when the relief is closed. That is, an "impedence" that strays outside of linear models where the filter gains PSID just due to flow that isn't on time with gained pressure generated by the engine.
Now when the pump relief is open
you can throw this linear relationship out the window and you can surely see all kinds of pressure differentials that don't normally exist where oil can only accellerate through the filter instead of having the option of going somewhere else. That's what a bypass valve limits.
I would love to explore this further because it's somewhat upsetting my whole belief in how some things work. I'm always open for learning something new and realizing the error of my problem solving methods and conceptual constructs.
I'd like to add that much depends on what test method you're using. In a zero pressure downstream return line, like the one in Grease's filter study where swatches were tested for flow at given PSID levels. This could surely result in a "bypass level" event if applied to an integrated filter. I the engine, however, it would fall into a heirarchy relationship of all resistances in the fluid cirucit. I don't think that anyone employs anything like the system that SWRI uses ..where they apply all standards to a given engine. That is, a tester would apply a flow through a filter with a downstream orifice that was to represent an engine.
[ August 04, 2006, 01:51 PM: Message edited by: Gary Allan ]