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from the Projects department...
Level control in sump
Continuous process industries, DCS questions. topic
Posted by Oswald on 21 April, 2008 - 12:24 am
I intend to control the level of sump. I have been using float switches but they get affected due to a lot of turbulence when pumps are running. I want something that I can mount onto the tank wall. I can be contacted at this email address: ochitsa @ hotmail. com


Posted by David on 23 April, 2008 - 1:16 am
Siemens makes an ultrasonic switch that performs real well on our sumps with suspended solids, where contact technologies get dirty or bridge. I think it's called the ULS200. It mounts up high, shoots down. The relay output is adjustable with a wide deadband for either pump down or pump up control.

Ultrasonic is not good if you have foam, because it sees the top of the foam as the level, but it doesn't care about dirt or grease in the liquid. Our sumps have turbulence, too, but it doesn't bother the Siemens unit.

David


Posted by Roy Matson on 23 April, 2008 - 11:30 pm
Oswald,

I assume you just want on/off control.

Conductive level switches work quite well.
I have often used just one switch in a sump.
High level starts pump.
Pump stops X seconds after high level clears
If pump runs for Y seconds assume that there is a high level.
X & Y would be dependent on your process.

With only one high level switch the float type usually work quite well as there is less chance of it getting tangled.

Hope this helps,

Roy

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