Sodium Sulfite

Definition

The common low-pressure oxygen scavenger that reacts directly with dissolved oxygen to form sodium sulfate. It is cheap, fast-acting, and easy to test in the field.

The reaction is 2 Na2SO3 + O2 yields 2 Na2SO4, a stoichiometric ratio of 7.88 ppm sulfite per 1 ppm oxygen, with about 10 ppm fed in practice to hold a 20 to 60 ppm residual. Its downside is that it adds sodium and sulfate dissolved solids, increasing conductivity and the blowdown needed to hold chemistry limits. Above 900 psi it decomposes into corrosive gases, so it is reserved for lower pressures.

Related concepts

Oxygen Scavenger · Sulfite Residual · Stoichiometry

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Part of The Blueprint of Water · 🧪 chemistry