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pH is High in the day time and normal in the night

In our process the pH of water arises up to 14 in the day time but in the night it comes down to normal value 6.7 or 7. The Ambient temperature here is 34 °C. We are using Yokogawa pH Meter. Is there any problem with the meter. Please guide.

Bawa Shankar
employee - Doha, Qatar
April 4, 2011

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Hi, Bawa. The pH of process water cannot possibly approach 14 -- that is the pH of concentrated sodium hydroxide (caustic soda [affil links] ). Please get yourself some buffer solutions and some pH paper so that you can quickly and inexpensively address situations like this. Good luck.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
April 5, 2011

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Correction, Ted. pH 14 would be equivalent to a 1.0N NaOH [1N NaOH on Amazon] concentration - about 40 g/L NaOH. Concentrated NaOH would be a higher pH that would likely exceed the ability of the pH meter. Still, your point is valid- it is not likely that they actually have a pH 14 effluent unless they have a serious upset.

Jon Barrows, MSF, EHSSC
GOAD Company

Independence, Missouri

April 5, 2011