The authoritative public forum
  for Metal Finishing since 1989
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Inline Testing of Fluoride

I am looking for a way of inline testing of incoming waste waters for fluoride. My waste treatment operators get slugs of waste from the hydrofluoric etching operation, we are looking for an indicator to tell them they have a problem.

Rick Stinnett
consumer electronics - Marion, Indiana, USA

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Rather than trying a hardware solution, such as fluoride selective electrodes (an automated system could run big $$$) why not just get the people dumping the concentrates to let you know when they are going to do it?

Bill Vins
microwave & cable assemblies - Mesa (what a place-a), Arizona
 

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It sounds like you may need a larger equalization tank! If that is not possible, then there are a couple of ways to get the alarm/notice you are looking for. The simplest and cheapest way is to install (fluoride resistant) conductivity sensor in your waste line. Any spikes will also have a much higher conductivity.

There are also two manufacturers of Fluoride analysers that can work over a very large concentration range and are in daily use at many semiconductor companies.

Lyle Kirman
consultant - Cleveland Heights, Ohio