Sulfite is added to boilers to remove dissolved oxygen, which causes severe pitting corrosion. Theoretically, it takes about 8 ppm of sodium sulfite to react with 1 ppm of oxygen.
Sulphite Test must be carried out properly to ensure efficient protection of feedlines and boilers from corrosion and enhancing protection against caustic embrittlement.
Sulphite reacts with oxygen rapidly.To assure that this reaction goes to completion and that all oxygen is removed, an excess of 30 to 70 ppm of sulfite should be carried in the boiler water.
To eliminate oxygen corrosion and assure that the sulfite/oxygen reaction is complete before the feedwater reaches the boiler, sulfite should be fed as early as possible in the boiler cycle - preferably to the deaerator storage tank, feedwater storage tank or feedwater line - rather than directly to the boiler drum.
- Ideal treatment for low and medium pressure boilers
- Rapidly reacts with oxygen preventing corrosion
- Take 10ml of water in a test jar
- Add 7-8 drops of Reagent RX-SI-1 . Mix contents well
- Add 3 drps of Reagent RX-SI-2 and mix well
- Add Reagent RX-SI-3 dropwise, counting the number of drops while mixing until a Blue Color appears .
Sulphite as ppm SO3 = 5 x number of drops of Reagent RX-SI-3