Overdrain Cup/Basket In Sand Filter

What's the purpose of an overdrain cup and basket/strainer in my American Meteor sand filter? See attachements - parts 9 (cup), 10 (basket), and 12(kit). Also, there is a closeup of the two parts.

While replacing my valve, the basket disintegrated. The basket holds the cup tightly against the underside of the multiport valve. The stand pipe is still perfect, and the overdrain cup is still in good condition.

So far, I have not be able to find the American (Pentair) basket (51030100) or kit (55025200).

What would happen if I omitted them during reassembly?

I also see reference to these same parts as American Products 26" Eclipse Valve Upgrade Kit (Before 11-95) 50124100.

If the purpose of the overdrain parts is to diffuse the incoming water into the sand filter, based on pictures it seems that my ordered replacement MPV valve (Praher TM-12-S8) may have a builtin diffuser.

But, overdrain is a confusing term to me.

I've never disassembled one of those filters, so I'm not completely sure.

But it appears that the #12 unit is the interior portion of the multiport valve, and provided BOTH the path the water takes ENTERING the filter, AND the path it takes LEAVING the filter. So, without it . .. you'd have no filter. The standpipe definitely provides the filtered water exit path.

The standpipe actually 1.5" PVC and is OK so I plan to reinstall it. The standpipe is centered through the middle of both the cup and basket.

You are correct - in normal filtered operation, the filtered water is forced through the sand and returns via the standpipe; unfiltered water is routed through the MPV, discharged into the overdrain cup, and then through the overdrain basket. I imagine this is to disperse the water 360 degrees, and reduce the velocity of the water stream which would continuously stir up the sand.

Perhaps I wasn't clear in my original message - I would reinstall the standpipe, which would allow filtered water operation to continue. But given that the basket isn't available, and without it the cup is useless, I am considering not installing these two items. Also, as said previously, the Praher MPV appears to have a dispersing design that the original MVP didn't have. So, if I'm right about the purpose of the overdrain cup and basket, I should not need them.

But, if the purpose of the cup/basket is water dispersal, why not call them that rather than overdrain???

Quote:

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Originally Posted by vgg659

But, if the purpose of the cup/basket is water dispersal, why not call them that rather than overdrain???

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Hm-m-mh. IDK. Because the companies don't hire English majors to name products or write manuals?

;)