With all the changes to Ammonia Refrigeration RAGAGEPs, many businesses forget that the IFC and their state fire code no longer cover refrigeration; they gave all that to IIAR. But since the IFC no longer covers refrigeration, how does NH3 get covered under the IFC? Is it flammable, toxic, or corrosive?
According to the 2021 International Fire Code (IFC), anhydrous ammonia is classified as a toxic gas. While it has unique properties that sometimes lead to specific exceptions in other industrial codes, the IFC is quite clear about its classification based on its lethal concentration (LC50).
The IFC defines a toxic material as a gas or liquid that has a median lethal concentration (LC50) in air of more than 200 parts per million (ppm) but not more than 2,000 ppm by volume of gas or vapor.
- Anhydrous Ammonia LC50: Typically cited around 2,000 ppm (for one-hour exposure).
- IFC Designation: Because it sits right at that threshold, the IFC categorizes it under Toxic (T) rather than Highly Toxic (which applies to materials with an LC50 of less than 200 ppm).
While it is classified as toxic, the IFC provides a significant “carve-out” for anhydrous ammonia with respect to Maximum Allowable Quantities (MAQ).
In many jurisdictions, the IFC allows a “limited” exception: anhydrous ammonia used as a refrigerant is not required to comply with the standard “Toxic Gas” regulations of Chapter 60, provided the system complies with Chapter 6 (Mechanical Refrigeration) and the International Mechanical Code (IMC).
Under the IFC and associated hazard ranking systems (like NFPA 704), anhydrous ammonia is recognized for a “trifecta” of hazards:
- Health: High toxicity and corrosive nature to skin, eyes, and lungs.
- Flammability: Classified as a Category 1B flammable gas (though it is notoriously difficult to ignite in open air).
- Reactivity: Low, but highly reactive with certain materials like copper, silver, and mercury.
Summary Table: 2021 IFC Profile
| Attribute | IFC Classification |
| Primary Class | Toxic Gas |
| Secondary Class | Flammable Gas |
| Physical State | Liquefied Compressed Gas |
| Permissible Exposure | Subject to PEL/TLV (typically 25–50 ppm) |