Grinder for sewage

Charbel · Apr 10, 2014

Dear,

Grinder at the inlet chamber for sewage will not be running all the time, it should be either connected to level switch or level transmitter. So i was wondering, ultrasonic is not very reliable in detecting the level sewage. So maybe i should be going with differential ultrasonic levels and connecting it to the grinder for its initiation.

what do u think about this arrangement? please find below the selected grinder:

http://www.franklinmiller.com/taskmaster-8500.html

thank you!

charbel

Bit_Bucket_07 · Apr 10, 2014

Ultrasonics are notoriously unreliable when an attempt is made to implement them in closed chambers, due to false echoes returning to the transducer. If you've already experienced problems with an ultrasonic level sensor, then perhaps you should consider a laser, radar or capacitive level probe instead.

Tom Jenkins · Apr 10, 2014

If all you need is on/off control I would just use a float switch.

Bit_Bucket_07 · Apr 10, 2014

Tom Jenkins said:
If all you need is on/off control I would just use a float switch.

It's always difficult to argue with implementation of the KISS principle!

jrwb4gbm · Apr 10, 2014

Tom Jenkins has a Sticky posted at the very top. See that thread for more info. There are float switches made for the sewage control environment and work very well. The only thing I can add is to use two or three switches for backup, each physically set slightly higher than the first.

RussB · Apr 10, 2014

Good information but I would recommend setting the floats as close to equal as possible and OR-ing them in logic. With verification testing that all are transitioning at regular intervals. Anyway if spills there are as costly as they are here.

Tark · Apr 10, 2014

We use these probes on lift stations, gives 10 levels of measurement, I have seen them completely covered with grease and still working -
http://www.multitrode.com/products/multismart-and-probes/liquid-level-sensing-probe/

We use this controller with the probe, gives 10 relay outputs and 4-20mA -
http://www.multitrode.com/products/other-controllers/mtic-indicator-controller/

We have found this to be more reliable than floats.

Tom Jenkins · Apr 11, 2014

Interesting product, Tark - especially the 4-20 mA output. I've used electrode level detection in clean water and some wastewater, but I'd be a little concerned about rags shorting across electrodes upstream of a grinder. Of course, for the cost of an ultrasonic the original poster could buy one of each to try and still come out with money in his pocket!

Tark · Apr 11, 2014

We have had these probes in service for at least 10 years and I've never seen a rag get wrapped up on one, I've seen plenty of rags wrapped up on floats though.

boneless · Apr 11, 2014

We have been using EH Liquiphant for level detection in boilers and in oil spill "buckets". Not sure how they would work in sewage with solids and all that..

http://www.endress.com/eh/home.nsf/#page/~product-news-liquiphant-m

Grinder for sewage

Charbel

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Bit_Bucket_07

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Tom Jenkins

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Bit_Bucket_07

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jrwb4gbm

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RussB

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Tark

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Tom Jenkins

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Tark

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boneless

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