Anyone familiar with an electrode well?

sparkie

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I'm looking at bidding what seems to be some standard pump controls for a local levy. The one thing that is giving me a bit of grief is this part of the system called "an electrode well". I was wondering if anyone could shed some light on that, as my google-foo has failed me.
 
WAG - a perforated pipe with an electrode inside.

The pipe protects the electrode, but isn't electrically connected to it, so the rectifier power supply current pulls whatever is in the water and plates it on the electrode, cleaning the water.

It might be that the well is charged (not the tank wall) and the current flows from it to the electrode cleaning the water inside it, as the water flows through it.
 
Hi, we had sacrificial anodes in a perforated pipe in our drinking water reservoirs when I worked for a water utility. Sort of like the ones that I saw on ships welded to the hull. The marine folks called those "zincs". They prevent electrolysis and therefore erosion and decay of metal parts submerged in treated water or salt water.
 
I'm thinking they might just be some sort of conductivity level sensor.
 
In this context is is a stilling well, a pipe in which the electrodes hang that will not allow turbulence in the well to disturb them and make them hit each other. From this diagram though, they indicate that the electrode well is grounded, so it must be made of a conductive material. The relays appear to be inductive, like BW or Warrick, and in those systems the other part of the inductive circuit path is the grounded walls. If the probes are in a grounded metal tank, the still well can be plastic, but if not, use a metal pipe as the still well.
 
Think it might be time to suggest an update to their standards! Maybe an additional service you can offer...

Omron do a floatless level switch which we use a lot over here. 61F is the start of the model number then pick what suits the application. They do electrode holders as well. Very easy to install into a DN100 PVC pipe if you need a stilling tube.

Is this fresh water or waste water? Conductive probes can be a real PITA if it's wastewater. They will develop a layer of fat and grease or get a rag wrapped around them if not regularly checked and cleaned. I prefer either a wastewater grade hydrostatic level sensor or a radar like the Endress FMR20.

If they will consider an alternative tender as well as a complying one, you can do this very easily with a PLC or RTU.

Our standard pump controls are primary RTU or PLC using an analog probe of some kind (dependent on client) and then a backup controller using float switches which we either just implement with relays or a little Zelio smart relay.
 
Thanks for all the information. Man, I want to bid this, but I will only have a whole day to bid in the entire project, and I have not been able to do a site visit. We just found out about this Friday, and not being familiar with what needs to happen with those level sensors worry's me a bit. There are also a couple motorized valves that actuate with the two 125 HP pump motors that I'm not quite familiar with.



Too bad. This is a good little job, but without a site visit to get eyes on what I'm looking at, I don't think I can work up a bid in a day.
 
Why would they use conductivity sensors and not just an ultrasonic in a stilling well?

You could bid it with specifing ultrasonics in stilling well. Multiple sensors in multiple wells for redundancy.

Valves. Motorized butterfly valves are readily available.

Valworx are typically quick to get.
 
I don't think that they had ultrasonics for this purpose back in the 60's when this system was built. The reason issue here is time. With all of that niche instrumentation, plus the standby power system needing retrofit, and no time to do a site visit, there is no way I could possibly bid this project. No way I'm walking into something like that without first putting some eyes on it.


Thanks everyone for all the information. I did learn a lot here.
 

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