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HVAC Waters

     

preventing glycol degradation
   
In the presence of dissolved oxygen, hot ethylene or propylene glycols oxidize and become organic acids: 

alcohol groups in glycols react with oxygen, forming carboxyl groups
(-COH + O becomes -COOH), 

carboxyl groups disassociate into carboxylic acids 
(COOH becomes COO- + H+)

Sulfite (sodium sulfite) reacts with oxygen, disallowing the the first reaction.
Maintain 20 to 50 ppm at all times.

pH buffer (dipotassium phosphate) neutralizes acids of the second. 
Maintain pH of 8 to 9 at all times.

for your information

sodium sulfite
94% sodium sulfite, anhydrous (Na2SO3)
100 lb. bag = $185 
Van Waters & Rogers 
800 234-4588

sulfite test kit 
model # K-1529 = $29  
 Taylor Technologies
800 638-4776 

pH buffer
 dipotassium phosphate
100 lb. bag = $385 
Van Waters & Rogers 
800 234-4588

pH meter
model #4435001 = $42
Hach Co.
800 227-4224