filter flow and placement of magnets on the top?

[63Avanti]

I have been using drain plug magnets for years, and always find some ferrous stuff hanging there. Not much, but at least it makes me feel good. Until the hint about lee valley magnets, filter magnets have been to expensive.

I am confused on one thing. Some of the people here put their magnets on the "top", by which I assume that they are referring to the end opposite the base. When I look at filter cut-aways, the oil comes in the outer holes and returns through the center tube. In the cut-aways I have seen, there is no oil in the "top", except in the unfortunate case where the filter media is clogged.

Why are people putting the the magnet on the "top?"

 

[Pete C.]

Because most of the magnets are dounut shaped and fit there the best. You're right to think that they should go on the sides where the oil flowes the most. Which means finding long rectangular magnets.

 

[Gary Allan]

Just my speculation as to the reason, but the oil would have to pass by the magnet as it entered the filter. If you place it on the bottom ...or nearer the bottom, much of the oil will not see the field.

Look at the filter as a dead end. It's almost like a "still well" where the oil changes velocity. You're basically filling up a bucket and adding more fluid to it. Depending on the flow rate, the fluid's going to want to take the shortest path to the exit. No reason for it to displace fluid in the bottom of the filter if it doesn't need to ..at least in a proportional manner. I imagine that you would see cascading plumes of flow that would lose velocity as they attempted to collide with fluid in the bottom of the filter ..finding it easier to take a right hand turn to the center tube.

In short, even if every square inch of media sees flow ..it won't be at the same flow rate ..at least when new. That would tend to saturate the upper media area before the lower. If you place magnets at the bottom less of your recycling sump will see them.

 

[jmsbntz]

You can get curved filter magnets from here. If you try one out please post, post-mortem examination results!

 

[63Avanti]

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Because most of the magnets are dounut shaped and fit there the best. You're right to think that they should go on the sides where the oil flowes the most. Which means finding long rectangular magnets.

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I bought the Lee Valley "40 pound" magnet and put them in a steel shell, at least "80 poinds". I very much doubt that the "curved" surface will have any affect.

 

[cmhj]

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I very much doubt that the "curved" surface will have any affect.

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But they do. I've been using the filtermag on several units for many years.

After running several thru a cyle I've cut them open. In every case metals fragments, though very small, were found in the gooy mess that's usually left behind much like any magnetic drain plug would.