Filters in parallel or in series
Filters in parallel or in series
(OP)
Hi Guys,
A sort of generic question:
If we were to use three identical filters, firstly with the two in parallel followed by the third in series, and then all three in series, which method would be the most effective in terms of impurities removal?(lets assume that the system you have is THF with carbon particles dispersed and try to keep it simple: The only parameter available is the flow rate, so, given that I use the same flow rate in the outlet of the systems (5 lt/min) for both systems, which one would get cleaner THF?
I'd appreciate if you could share your opinion
A sort of generic question:
If we were to use three identical filters, firstly with the two in parallel followed by the third in series, and then all three in series, which method would be the most effective in terms of impurities removal?(lets assume that the system you have is THF with carbon particles dispersed and try to keep it simple: The only parameter available is the flow rate, so, given that I use the same flow rate in the outlet of the systems (5 lt/min) for both systems, which one would get cleaner THF?
I'd appreciate if you could share your opinion





RE: Filters in parallel or in series
RE: Filters in parallel or in series
I mentioned that all 3 filters are identical,
Thanks for that,
Zicos
RE: Filters in parallel or in series
For the filters in series, the two in front will take most all the load. The flux is cut in half, so efficiency increases slightly, but the cake is also divided between the two. This improves pressure drop, but reduces efficiency. If in the first scenerio (with the filters in series) you used 100% of the filter capacity, in this parallel scenerio, you now used two filters, but only half the capacity for each. Again, the third filter is relatively useless. The real reason for filters in parallel is to reduce the pressure across a single filter. Suppliers prefer multi-round housings rather than parallel piping because it: A) makes them more money and B) evenly distributes the filter load when compared to parallel plumbing legs that do not have identical pressure drops. (i.e. the filter in the shorter leg of piping gets most of the work)
In short, if you want to increase efficiency, you can have a dynamic system, where the "caked" filter gets transfered to the third position in series after a cake builds up... OR... follow ash9144's recommendations, which is industry standard.
Hope this helps. Was this more of a philisophical question (i.e. class assignment), or are you looking for a practical solution?
Aaron A. Spearin
ASQ CSSBB
Engineering Six-S'$
www.Engineering6ss.com
"The only constant in life is change." -Bruce Lee
RE: Filters in parallel or in series
thanks a lot for your views, it does help, and no this is not an assignment, it is a real project i want to sort out...we already have a system with 2 parallel and one in series and thinking about converting to all 3 in series...
Regards
RE: Filters in parallel or in series
Does it make sense if we assume an electric analog (thinking of the filters as resistors)where, in series the total resistor would be 3R whereas in two parallel and one in series, the total resistance is 1.5R?
what do you think of that?
RE: Filters in parallel or in series
Note though that this does not take into account that delta P across a filter changes over time as aspearin described. Filters in series will disturb the downstream and/or the upstream unit in the sense that it upsets the pressures. Filters in parallel (OK unless you put a third one in series...) will do that much less as long as you change them diligently one at a time.
RE: Filters in parallel or in series
two should be in series and the third at stand by,
after the cake is built on yhe first one (dp control) switch between the first and the second (by piping design) so the second one with the cake will catch the smaller particles. The stand by filter will replace the first one while the second one will be cleaned.
All by dp control.
regards,
roker
RE: Filters in parallel or in series
Aaron A. Spearin
ASQ CSSBB
Engineering Six-S'$
www.Engineering6ss.com
"The only constant in life is change." -Bruce Lee
RE: Filters in parallel or in series