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Posted by Mike Boyle on November 08, 2005 at 11:23:55:
In Reply to: Re: sulfite posted by A Boilerguy on November 02, 2005 at 17:01:27:
: : da tank@12pounds temp@240 cannot maintain a high sulfite count boiler rated at 60000 pph @125 sulfite is added to the d.a. high reading one day the next day almost zero reading taken from the boiler
: You may want to check your reagents or the batch of sulfite if you haven't already, we have experienced this problem in the past.
Make sure you are NOT using a catalyzed sulfite. Our outside sales guy worked as a regional manager for an industrial water treatment company for 7 years. This is his take on it: Catalyzed sulfite uses cobalt to speed up the reaction with cold water. There is a reaction time for sulfite to react with dissolved O2 in the water. The colder the water, the longer it takes sulfite to react. You mainly need a catalyzed sulfite under a feedwater temp of 140 F.
The problem with a catalzyed sulfite is that it reacts very quickly with oxygen in the atmosphere. Unless you put a floating blanket over the catalyzed sulfite solution, you will have a chemical tank full of dead sulfite 24 hours later.
You do not need a floating blanket with regular anhydrous sulfite and it will react instantaneously with 240 F feed water.
Double check this and/or check with your water treatment rep to see if they are using catalyzed sulfite.
Another thing to consider is you will get your most accurate sulfite reading from a cooled sample (hot samples will read higher). If you do not have a sample cooler on your boiler, fill a jar, beaker, or bottle with the sample to the top, and cap it to cool it (do not leave any air in it). If you allow it to cool to the open atmosphere, you will get a reading of zero on your sulfite as the water will absorb oxygen as it cools if left open. The standard test for sulfite is to test excess sulfite only (most reps recommend 30-60 ppm excess), that does not take into account all the sulfite which has already reacted with O2 in the water.
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