Continous Liquid Concentration Sensor

We are in the need of a continous liquid concentration monitor. Our die cast deptment uses a mixture of water and die lube at 60:1. We need to know when the concentration gets to 30:1 or less. The concentration is calculated with a plc and is done in small batches in a 7 gallon holding tank. The solution is then pumped to each machine via an overhead manifold.
A low concentration causes the parts to stick in the dies. An increase in contration is ok. Analog or digital signal is ok too.
I would like to flag a bit in the plc to set off an alarm. Any suggestions or experiences with anything type of sensor that will accomplish this?

Thanks,

Steve Meisel

No expert but?

Steve,
I do not have any direct background in the area you are interested in, nor am I a chemist. However, check out Omega Engineering and see if this might do for your needs. This little conductivity transmitter is kind of pricey, but you know what they say? Might give you an idea if nothing else. Good luck.

You might try a refractometer. These folks have a digital and analog version.

http://www.atal.nl/uk-part/datasheets/atwq.pdf

You'll probably have to figure out a way to acquire samples automatically.

Try LSC corp or Electron Machine Company 800-874-0627. Electron Machine is a refractometer type sensors can be calibrated to the type of fluid you are using. I have used LSC to monitor black liquor solids and Electron Machine to monitor paint solids. Both will give online measurements in 4-20ma. Neither is cheap.