Sodium Chlorite Storage & Tank Compatibility

Storing Sodium Chlorite? Start Here

Sodium chlorite (NaClO₂) is an inorganic chlorine-oxygen salt used chiefly as the on-site precursor for chlorine dioxide and as a bleaching and disinfection agent in pulp, textile, food-processing and municipal water treatment. It is most commonly shipped and stored as a stabilized aqueous solution rather than the dry crystalline solid, because the solid is a vigorous oxidizer that can ignite or detonate when mixed with combustible or reducing materials. In solution it remains a strong oxidizer and a corrosive, toxic chemical that demands oxidizer-rated containment, careful segregation from acids and organics, and dedicated transfer hardware. For polyethylene tank service the key questions are solution concentration and operating temperature, both of which govern how aggressively the oxidizer attacks the resin over time.

Sodium Chlorite in Polyethylene (HDPE / XLPE) Tanks

Honest verdict: conditional. Published polyethylene resistance charts rate dilute sodium chlorite solution (roughly 2 to 20 percent) as resistant (S) at ambient temperature near 68 F, limited (L) around 140 F, and not suitable (NS) approaching 212 F. Because sodium chlorite is a strong oxidizer, the rate of polymer attack rises steeply with both concentration and temperature, so a tank that performs well storing cool, dilute solution can degrade quickly under hot or concentrated duty. For ambient-temperature storage of dilute aqueous sodium chlorite, an HDPE or crosslinked (XLPE) tank with oxidizer-compatible gaskets and fittings is a reasonable choice. Specify thicker walls for margin, keep the tank out of direct sun and away from heat, avoid concentrated feed stock in PE, and confirm the exact concentration and temperature against the manufacturer chemical resistance chart before committing. When in doubt, PVC, CPVC or titanium are the more conservative wetted materials.

Material compatibility at a glance

Sodium chlorite is a powerful oxidizer most safely handled as a dilute aqueous solution. PVC, CPVC, titanium and FKM (Viton) are the workhorse wetted materials. Polyethylene (HDPE / XLPE) and polypropylene are acceptable for cool, dilute solution storage but must be derated as concentration and temperature climb, because oxidizer attack on the polymer accelerates sharply with heat. Carbon steel, 316 stainless, and natural-rubber elastomers are unsuitable.

Ratings: S suitable · C conditional / limited · U unsuitable. Verify against the cited resistance charts and your concentration/temperature before specifying.

The safety that actually matters

• Strong oxidizer: store away from acids, organics, reducing agents, sulfur, and all combustibles; contact or contamination can cause fire or explosion (H271, H272).
• Acutely toxic by every route: fatal if inhaled, fatal in skin contact, toxic if swallowed (H330, H310, H301) and severely corrosive to skin and eyes (H314, H318).
• Use full chemical splash goggles, face shield, oxidizer-resistant gloves and apron, and respiratory protection; provide eyewash and safety shower at the point of use.
• Never mix with acid: acidification liberates chlorine dioxide and toxic gases. Keep dedicated, clearly labeled transfer equipment.
• Very toxic to aquatic life (H400, H410); bund the tank and prevent any release to soil, storm drains, or surface water.
• In a fire, the solid intensifies combustion and may explode; flood with large amounts of water from a protected distance and evacuate the area.

Common questions

Can I store sodium chlorite in a polyethylene (HDPE or XLPE) tank?

Yes, conditionally, for cool, dilute aqueous solution. Resistance charts rate dilute solution as resistant at ambient temperature but only limited near 140 F and unsuitable near boiling. Specify oxidizer-compatible gaskets and fittings, keep the tank cool and out of sunlight, and verify your exact concentration and temperature against the manufacturer chart.

Why is sodium chlorite only rated conditional rather than fully compatible in polyethylene?

It is a strong oxidizer. Unlike an inert salt, an oxidizer slowly attacks the polymer, and that attack accelerates sharply with temperature and concentration. So while dilute cool solution is fine in PE, hot or concentrated service is not, which is why it earns a conditional rather than an unconditional rating.

What tank and seal materials are safest for sodium chlorite?

For wetted service PVC, CPVC and titanium are the conservative choices, with FKM (Viton) for gaskets and seals. Carbon steel, 316 stainless steel, and natural-rubber or nitrile elastomers are unsuitable because the oxidizer and chloride content corrode or degrade them.

What is the NFPA 704 rating for sodium chlorite?

Per CAMEO Chemicals (NOAA), sodium chlorite is rated Health 1, Flammability 0, Instability 1, with the special OX designation for oxidizer. It will not burn itself but will intensify a fire and supply oxygen to combustibles.