Figure 1. NFPA Hazardous Materials Placard: NFPA 704 provides a simple, readily recognizable, and easily understood system of markings that provides a general idea of the hazards of a material and the severity of these hazards as they relate to emergency response. The standard does not tell you when such labels are required but provides the criteria for labeling when such labels are required by another code, standard, regulation, or jurisdiction.

In this month’s Harrington Group, Inc.’s, “Think Upstream”, we take a look at Maximum Allowable Quantity (“MAQ”) for hazardous materials and what it could mean for your facility.

What is a Maximum Allowable Quantity?

The Maximum Allowable Quantity (“MAQ”) for hazardous materials can be simplified as the quantity of a given hazard permitted in a facility without requiring dedicated, highly protected areas for storage or use.

What are hazardous materials?

Hazardous materials are those materials that present a physical hazard (explosions, fast-spreading fire) or a health hazard (toxicity, corrosivity) beyond ordinary combustible storage. The special hazards involved require specialized protection to manage the risk. Common hazardous materials include aerosols, flammable and combustible liquids, toxics, corrosives, organic peroxides, and oxidizers.

Is the MAQ for the entire building?

Fire and Building Codes limit the MAQ into rooms what are termed “control areas.” A control area is limited between exterior walls or 1-hour fire resistance rated barriers. A building without internal fire resistance rated barriers is considered a single control area, and the MAQ limits apply to the full building. If the building is subdivided with multiple 1-hour fire resistance rated rooms, then each subdivided area can store or use up to the MAQ.

How much is too much?

The amount permitted is related to the hazard of the material being stored or used. Some low hazard materials (Class IIIB combustible liquids such as motor oil) are unlimited in sprinklered buildings. However, higher hazard materials (Class IB flammable liquids such as rubbing alcohol) are limited to as little as a pallet load. The intent is that the occupancy only has a minimal, incidental amount of hazard.

I already meet DOT standards, why is this different?

Department of Transportation (“DOT”) classifications and standards apply to materials in transit and generally only regulate materials once they are on a vehicle. Fire and building codes apply to storage and use of materials inside[1] of buildings, even staging of materials awaiting shipment. Additionally, DOT classifications are like, but not identical to fire and building code definitions. As an example, definitions of toxic materials differ, and the fire and building codes do not consider environmental hazards in determining hazard.

How are Hazardous Materials evaluated?

Each type of hazard and the maximum quantity at a given time in storage or use must be tabulated. Where specific hazardous material categories exceed the MAQ value, relevant chapters of the fire and building codes will provide required protections. An evaluation may begin with a review of an inventory list, DOT classifications may be used as a first pass, but a review of material Safety Data Sheets (“SDS”) must be used to properly classify materials.

What’s Next?

Once the hazardous material quantities are known, the project team can review the relevant sections of the fire and building codes to identify what protection measures are required for the building. This may include fire-resistance rated barriers, secondary containment, enhanced fire sprinkler systems and alarm systems. While the fire and building codes provide prescriptive requirements, they cannot address every configuration and use of building possible. For that reason, the codes also permit the use of performance-based design alternatives where a project team will work with the jurisdiction to develop a building solution that meets the intent of code requirements through addressing the specific hazard.

“Think Upstream” and plan for expansions, new processes, or new facilities by evaluating your hazardous materials and determining the adequate protection schemes at the beginning to avoid unexpected costly changes later.

[1] Yard storage or storage outside of buildings is also addressed by fire and building codes.