#WishIknew – How do I find solution’s concentration with conductivity sensors?
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I wish I knew how to find solution’s concentration with conductivity sensors!
Sometimes you need to know more about a solution’s concentration than its conductivity. Luckily these parameters are related, so you can measure both with the same sensor.
Unluckily, they don’t have a linear relationship. Most solutions have a peak conductivity value. Normally, before this peak, the concentration and conductivity correlate positively – higher on one equals higher on the other. Beyond this peak, however, this correlation shifts.
Therefore, you can’t measure concentration in the full range of the conductivity-concentration curve. You’ll have two or more concentration values for a certain conductivity value.
Now, a transmitter may have the curves for common solutions pre-stored in its memory. But if it doesn’t have your solution, then you’ll need to build a table with empirical values. Your table must address three data points, conductivity, concentration, and temperature.
To make it easier, keep a constant temperature and adjust the concentration. Note here that you’ll get identical values of conductivity for different values of concentration. As soon as you complete the data for that temperature, you can change the temperature and start again.
After you finish your table, you can feed it to your transmitter. Then you’re good to go!