In article , Steven Shelikoff
wrote:

My 'read' from your statment is that perhaps you miss the functional
point of a recirculation filtration system - which is using a filter of
LARGE pore/rentention size to eventually wind up with a fluid with very
few very small particles.

A recirc filter only removes a paltry few percent of the 'target' size
particles (for example 5% of 2uM particles.). A large pore size filter
will have very little resistance to flow, will have more permeability
(open space), will have more ultimate 'dirt capacity'. If you pass the
fluid 20 times through the filter, you will remove approximately a
value approaching 100% of the target particles. With the same pump, a
LARGE filter is be able to pass a LARGE volume very quickly, whereas
2uM filter will take longer (due to resistance to flow - pump slows
down or starts to slip and fluid begins to bypass the vanes, etc. ).

For single pass filtration (and without knowing the particle size
distribution) one typically needs a prefilter of the same surface area
(or dirt capacity) that is 5 times the size of the final filter.
eg.: 10uM followed by 2uM, where the prefilter is used to prolong the
life of the final filter. This is somewhat simplistic. When you
design a filtration system with a prefilter or multistage prefilters
one typically attempts to make ALL the filters fail at the exact same
time - so maximum debris is removed and the cost of change is minimized
- and you dont throw away filters that still have some capture ability
left in them.



Why not just always leave the polishing system in-line? Allow for a
bypass to change a filter or if it develops a vacuum leak, but other
then that, there's nothing wrong with always using "just polished" fuel.

Steve