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Conductance switch for pump level control

Conductance switch for pump level control

(OP)
A pump supplier is suggesting we use a conductance switch - eg Warrick type - for pump on/off actuation. I'm not personally familiar with this type of pump actuation and would like to know whether conductivity based liquid level control is used often, and in what applications?

The pumps are for removal of groundwater from under a lined pond and/or leak detection. The water will be either clean river water, or process water with some TDS (in the leak detection case).

RE: Conductance switch for pump level control

Hi Bob,

I've personally never used a conductance switch, but in my experience simplicity is better (especially when it comes to operations understanding how it works and how to fix it). I've always found I was able to have my groundwater flow to a sump where simple on/off switches suffice.

I understand that conductance is useful for finding even the least bit of moisture, but given that pumps still require a certain suction head before pumping can commence I would say it seems more useful as a switch for an early warning indicator then for turning on and off a pump which requires a foot or so of water where a float switch would easily suffice.

My 2 cents,
Chad

RE: Conductance switch for pump level control


PetroBob ,

The pumppig company guy is trying to sell you something.

Use a float instead. It's cheaper to buy and easier to maintain.

In mining we use two floats, for maximum and minimum water levels.

Some mining guy.

Ingenieur Minier. Québec, Canada.

RE: Conductance switch for pump level control

A conductivity rod (such as the MulTitrode) can be used. There are no moving parts and no electronics associated with it, so it will last for 20+ years. That's why it comes with a 10-year warranty. No other liquid level sensor comes close.

http://www.multitrode.com/products/multismart-and-...

http://books.google.com/books?id=biWHfrpd9gsC&...

In lift stations, the conductivity rods work well when there is debris in the water. An additional float is commonly used as an separate emergemcy high alarm.

In the overall scheme of things, one would doubt the cost of the switch would be significant. However, if long term reliability is a concern, you might prefer the conductivity rod.

RE: Conductance switch for pump level control

(OP)
Thanks for the input folks. In this instance reliability and minimizing maintenance are more important than cost.

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