UN 1498 — Sodium nitrate

Sodium nitrate is a white to colorless crystalline solid, used in the production of fertilizers, explosives, and other industrial applications. It is classified as a DOT class 5 oxidizer and is widely used in various industries. First responders may encounter sodium nitrate in the event of a fire or explosion, and it is essential to handle it with caution due to its potential to accelerate burning and decompose explosively when heated. The scale of production and transport of sodium nitrate is significant, and it is crucial for emergency responders to be aware of its hazards and take necessary precautions. Sodium nitrate is also known by its synonyms, including nitric acid sodium salt, soda niter, and Chile saltpeter. Its CAS number is 7631-99-4.

Hazard overview: Sodium nitrate is a strong oxidizer that can accelerate burning and decompose explosively when heated, with a boiling point that is not applicable due to its decomposition above 380C (716F). It may ignite combustibles, such as wood, paper, oil, and clothing, and can react explosively with hydrocarbons. The substance is odorless and has a hygroscopic property, which can cause it to form caked masses when exposed to moisture. When involved in a fire, sodium nitrate can release toxic fumes, including nitrogen oxides and sodium oxide. The LC50 value for sodium nitrate is not available, but it is known to be highly toxic and can cause severe health effects, including respiratory problems and skin irritation. In a worst-case scenario, sodium nitrate can explode from heat or contamination, causing significant damage and harm to people and the environment.

Response guidance: In the event of a sodium nitrate spill or fire, it is essential to isolate the area, with an initial isolation distance of 100m in all directions, and consider evacuation if a fire or large spill occurs, with an isolation distance of 800m downwind in daytime, and 1600m at night. Emergency responders should use water spray, dry chemical, or CO2 to suppress the fire, avoiding organic materials and combustibles near the oxidizer. Decontamination is crucial, and CHEMTREC should be contacted in case of an emergency. The use of SCBA and Level C minimum PPE is required for handling, with a focus on avoiding all ignition sources and contamination with organics.

Firefighter training notes: Emergency responders should be trained to handle sodium nitrate with caution, with a focus on avoiding ignition sources and contamination with organics. A common tactical error is underestimating the potential for explosion and fire, and it is essential to have a clear understanding of the substance's hazards and risks. The ICS position needs to be aware of the potential for sodium nitrate to accelerate burning and decompose explosively, and mutual aid criteria should be established in case of a large-scale emergency.

Regulatory context: Sodium nitrate is classified as a DOT class 5 oxidizer, with a packing group that is not available. The OSHA PEL/TLV for sodium nitrate is not well-established, but it is known to be highly toxic and can cause severe health effects. The substance is not on the CERCLA list, but it is essential to handle it with caution due to its potential to accelerate burning and decompose explosively.

Storage & handling: Sodium nitrate should be stored in a cool, dry place, away from incompatible materials such as hydrocarbons and combustibles. The temperature limit for storage is not available, but it is essential to avoid heat sources and ignition sources. Ventilation standards should be followed, and containers should be designed to prevent contamination and leakage.