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Posted by BoilingMan on July 30, 2002 at 12:00:54:
In Reply to: T.D.S. posted by Andy on July 22, 2002 at 18:11:02:
: While preparing a sample of boiler water from a 60 bar boiler to take a tds,the water is cooled and then neutralised. Now my question is that i am neutralising with a powder (Galic Acid),now i understand that this neutralising is to drop the pH of the water from pH 10.2 to around pH 8.3 ,the point where phenolphaelin colour dissapears,so having reduced the OH ions to reduce the conductivity ,Ok so how is it i am disolving a solid powder into my water and it doesn't affect the dissolved solids reading.????? it is a solid and it has just been disolved.
: Double checking the tds reading using N/10 sulphuric acid to neutralise the solution gives same tds reading.
: Using the finished sample from the total alkalinity test (pH 7) gives the same result.
: Some people say its because its a buffer solution,but how can that be when as an acid it will reduce the pH of the solution below 7 and add H ions making it acidic.
: If anybody can explain this little puzzle to me i would be grateful as it has been puzzling me for a few years.
: Thanks in advance
Don't be confusing with ions and other things.
Every things are more simple.
By neutralising the water sample we just simple substracting that part of chemicals, which we contributed as a treatment.
Because real water in the boiler consists of Ca,K, Na, other "nutritions" dissolved in the water and chemicals which we introdused to it.
Therefore w/out neitralising your reading will be much higher.BTW I did check it in my boiler w/out and with neutralising it was 2500 ppm and 1400 ppm accordingly.
Therefor don't be confusing with powdered
gallic acid,because it is "solid"!!!
Hope, i helped you and myself as well!
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