Fire and building codes define the Maximum Allowable Quantities (MAQs) for buildings based on the material’s hazard classification. While the details are complex, the goal is simple: limit hazardous material quantities to reduce risk to people and property.
If the building will have a quantity above the MAQ, the building requires a high-hazard (group H) occupancy group. Consequences of having a high-hazard occupancy are outside the scope of this blog but generally include architectural, fire protection, and mechanical design requirements that are more conservative than for other occupancies. These features add safety but also add cost to a design.
The codes in effect in the United States differ by state and municipality. In general, the relevant building and fire codes are:
Both ICC and NFPA publish an edition of their fire code every 3 years. Municipalities then adopt a specific edition, usually with some modifications.
For this article, I will focus on the 2021 editions of these codes. It is important to check which edition of each code is statutory for your facility and if there are any modifications by the local municipality.
The following tables provide the base numbers for MAQs of most hazard classifications. Some common hazard classifications are corrosive liquids, toxic gases, flammable solid, and oxidizing gases. These are the allowed quantities per control area. More on control areas later.
One notable exception in Hallam-ICS’s scope of work is that NFPA 1 does not provide requirements for dispensing, handling, transfer and use of ignitable liquids. Those requirements are in chapter 18 of NFPA 30.
It is worth noting that IFC and NFPA MAQ requirements are usually but not always harmonious.
The values in the tables above have adjustments and exceptions that change the MAQ. We recommend a thorough code review for these items. Some major items of note are:
One option to increase the amount of hazardous material on site is to provide multiple control areas in a single building. To do this the control areas need a barrier with a fire resistance rating. Exceeding MAQs may also trigger requirements for spill control and secondary containment, which often coincide with control area design and fire-rated barriers. This barrier includes walls and ceilings separating the control areas. For most projects the architect works with design engineers and the owner to understand the quantities of material in the building and defines control areas based on those quantities and locations.
NFPA 1 and IFC have similar tables that provide the number of control areas per floor as well as the required fire resistance rating between control areas.
One common example of using control areas is university lab buildings. Often the architect can intelligently split the building up into multiple control areas. When done well, this can allow the owner to operate as they wish while maintaining code compliance and safety.
We recommend taking the time in the building’s design to determine what control areas will work for the building’s lifetime. These are relatively cheap to add to a new building but can be challenging and costly to modify after the building is constructed.
Another option to increase the amount of hazardous material on site is to design a portion of the building to be a high-hazard occupancy. One common approach is to design only a storage area or room for a high-hazard occupancy. This allows designing the remainder of the building without the constraints of a high-hazard occupancy. When done well, this can reduce the project cost while maintaining code compliance and safety.
Providing a high-hazard space in the same building as another occupancy is code compliant but does require separation between the occupancies. The 2021 IBC provides these requirements in table 508.4.
One common example of this is gas storage. Many facilities that require large quantities of hazardous gas cylinders designate a gas room. These rooms may contain gas cabinets depending on the gases, quantities, and owner preferences. Generally piping from these rooms distributes gases from the gas room to the point of use. We frequently see this in university laboratory buildings and semiconductor facilities.
Another example of the use of building separation is chemical storage rooms. This can consist of storage containers that are stored in the high-hazard space and moved to the point of use in small quantities. In some facilities chemical storage rooms also include systems that distribute liquids to the remainder of the facility via piping. Semiconductor facilities use this approach frequently.
Understanding MAQs early in the design process helps you stay compliant, avoid costly redesigns, and improve safety. If your team is planning a facility with hazardous materials, Hallam-ICS can help with code review, engineering guidance, and control area strategy. Contact us to get started.
About the Author
Ash Kreider is a Mechanical Engineer at Hallam-ICS. He has process engineering experience in multiple industries. He currently designs systems for a wide range of applications including gas distribution, cryogenic fluid recovery, process equipment hookup and HVAC.
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About Hallam-ICS
Hallam-ICS is an engineering and automation company that designs MEP systems for facilities and plants, engineers control and automation solutions, and ensures safety and regulatory compliance through arc flash studies, commissioning, and validation. Our offices are located in Massachusetts, Connecticut, New York, Vermont and North Carolina Texas, Florida and our projects take us world-wide.