Wet Well Floats & Rags?

[sjohns4]

Hi All,

I'm working with a municipality who has a few typical submersible wastewater pump stations that have ragging problems. The controls use good old-fashioned relay logic with float switches.

These stations have very bad ragging problems. We have plans for a grinder at the upstream station that collects the rags before pumping down the line to the other two, but it's probably at best a year away.

The immediate problem seems to be the rags collecting on the float switches. Recently a float laden with rags became tangled with another float and caused some issues.

Due to the hatches that are barely large enough to pull the pumps there isn't much room between the floats.

I was wondering if maybe installing a float tree, where all of the floats are in-line vertically, would help avoid tangles caused by the debris floating around in the wet wells.

Has anyone had any experience in a situation like this they could lend?

Thanks,

Mike

 

[danw2]

If there's no foam and there's an unobstructed shot downwards, an ultrasonic level 'switch' can trip at a level point and rags won't hinder the shot.

The Siemens ULS 200 has a relay output that fits well into relay logic.

Ultrasonics can not distinguish between foam and water, so don't use if there's foam.

 

[bimr]

Agree with danw2.

Many users use the ultrasonics for level control with the float switch being an emergency high alarm.

 

[QualityTime]

You might want to think about enclosing the floats in a large diameter pipe

 

[stanier]

Why not put a PVC pipe shroud around the floats to keep the rags away?

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