1
$\begingroup$

I am reading the drawing for an automatic caustic dilution system where 50% NaOH is diluted down to 20%.

I was expecting to see a density sensor on the outlet to provide feedback to the dilution pumps for ratio-ing. i.e. To keep the density at 20% and prevent it from moving to say 19% or 21% by adjusting the amount of water.

However, the vendor seems to have used a conductity sensor on the outlet instead. I am skeptical whether the conductivity of NaOH will vary a lot between 19% to 21%. Isn't it already fully ionized?

Thoughts? Will this work?

$\endgroup$
  • $\begingroup$ Yes 19-21% solutions are fully ionized, but the relative amount of water is different so the conductivity changes. $\endgroup$ – MaxW Jan 19 '18 at 16:23
  • $\begingroup$ Thanks. Any idea about what would be the percent variation in conductivity between say a 19% vs 20% solution? $\endgroup$ – curious_cat Jan 19 '18 at 17:53
  • $\begingroup$ Relax as for conductivity measurements allow for quantitative analysis of electrolytes. It will work $\endgroup$ – Alchimista Jan 19 '18 at 21:44
  • $\begingroup$ Relax as for conductivity measurements allow for quantitative analysis of electrolytes. It will work $\endgroup$ – Alchimista Jan 19 '18 at 21:47
  • $\begingroup$ As conductivity and concentration are linearly related over small regions I'd guess that in going from 19 to 20% the conductivity would increase by a factor of 20/19. $\endgroup$ – A. J. deLange Jan 23 '18 at 14:25

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.