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Old 03-24-2002, 02:39 PM
adamrei adamrei is offline
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Join Date: Mar 2002
Location: Los Angeles
Posts: 31
Bypass effectiveness BMK13 vs. BMK11

Seems I am still looking for an informed mind on this. The BMK13 setup looks attractive for maintenance purposes but I still have an unanswered previously posted concern (reply):

Thanks for yor reply. I was referring to the BMK-13 diagram shown by ck42 (a reply to bypass filtration post by LightMan)and applicable to those of us that have spin on oil filters. It seems to me from the picture (BMK-13 diagram) that since the bypass and full flow filters operate in parallel in this set up, and the intake and exit pressures differ by the pressure drop across the lines, then the effective pressure across the bypass filter seems to be rather small. An electric analogy may work here, if you have a small resistor (full flow) in parallel with a large resistor (bypass) the current division states that most wil flow through the full flow with the voltage drop (pressure differential) being the same across the two elements. So, when compared with the set-up of outlet return to the sump (The BMK-11 setup) I think that the effective pressure is the oil pressure minus crankcase pressure. This effective pressure seems to be significantly higher than the BMK-13 set up, and since the bypass offer significant restriction to flow due to its arrestance rating (1 micron?) it would seem to me that it would work/flow better and clean faster with a higher effective pressure. Can somebody shed some light on this observation please? Thanks.

so, BMK-13 looks attractive but when compared to the BMK-11 it seems to be way behind in flow/effectivenes/speed of contaminant removal since all are directly proportional to the pressure across the bypass filter element. Please comment. Thank you.
Adam Reinosa
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