What is MAQ for a High Hazard H-3 Occupancy?

4/7/2023

We have a customer who is building a storage building that includes flammable liquids.

The liquids are Class I-B flammable (as classified under NFPA 30).

I understand that there are limits for the quantity that is allowed within one control area. The Maximum Allowable Quantity (MAQ) is 120 gallons, from NFPA 30 tables. The reading can be increased 100% when a sprinkler system is used.

So the limit increases to 240 gallons with sprinkler protection.

The number can increase even more when stored in approved liquid storage cabinets or safety cans, which I assume the customer would prefer.

So the final MAQ becomes 240 gallons x 2 = 480 gallons.

The biggest storage room is 2,000 square feet and the customer wants to exceed the MAQ to be above 480 gallons in that storage room.

I have understood that exceeding the MAQ is permitted if the building is classified as an H-3 Occupancy (High Hazard). This occupancy applies more restrictive requirements.

Is there any numerical value for a new MAQ limit in that case?

My current path is as follows:
Class I-B liquid storage in Storage occupancy > maximum MAQ exceeded > building re-classified as H-3 Occupancy > but where is the new MAQ?

Thanks in advance for your input. I usually design under SFS and CEA standards, and they don't have the same MAQ concept within those standards.

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11 Comments

Eric R

4/7/2023 08:24:39 am

From NFPA 30 if you follow the proper protection schemes for the storage arrangement then you can classify the room as a liquid warehouse per section 12.6.2 (of the 2021 edition). This would then give you an unlimited MAQ. There is also some language allowing for a MAQ higher than your 480, but less than unlimited if you sprinkler the space but not to the level needed to meet the definition of "protected", but it's not a code path I'd want to wrangle with.

Relatively correlated language is found in the IFC under section 5704.3.8(again of the 2021 edition).

These code sections are pretty dense, so I don't feel I can give a more full answer in this format, but if you check out these two sections you should be able to get to where you need to be.

Glenn Berger

4/7/2023 08:27:35 am

Once you classified the facility (or space) as H-3, then you are no longer going for the "Control Area" designation.

Chad

4/7/2023 08:32:57 am

Good starter article in regards to addition protection levels required once you exceed the MAQ's..... typically, there is no prescribed limit at that point

https://www.nfpa.org/News-and-Research/Publications-and-media/Blogs-Landing-Page/NFPA-Today/Blog-Posts/2022/08/12/NFPA-and-IBC-Occupancy-Classifications-when-Hazardous-Materials-are-Present

Todd E Wyatt

4/7/2023 08:42:01 am

Once the MAQs of a specific Hazardous Material (HM) are exceeded, that portion of the building is required to be classified as the “Group When The Maximum Allowable Quantity is Exceeded” which for “Flammable Liquid IB” would be “H-2 or H-3” per the scoping Code : 2021 IBC (TABLE 307.1(1)MAXIMUM ALLOWABLE QUANTITY PER CONTROL AREA OF HAZARDOUS MATERIALS POSING A PHYSICAL HAZARD).

Once the MAQs are exceeded and the “Storage” occupancy is re-classified as a “Hazardous” occupancy, there are no Code MAQs for this reclassification.

Per 2021 IBC, H-2 & H-3 are defined as follows :

307.4 High-Hazard Group H-2 Buildings and structures containing materials that pose a deflagration hazard or a hazard from accelerated burning shall be classified as Group H-2. Such materials shall include, but not be limited to, the following:
Class I, II or IIIA flammable or combustible liquids that are used or stored in normally open containers or systems, or in closed containers or systems pressurized at more than 15 pounds per square inch gauge (103.4 kPa).

307.5 High-Hazard Group H-3
Buildings and structures containing materials that readily support combustion or that pose a physical hazard shall be classified as Group H-3. Such materials shall include, but not be limited to, the following:
Class I, II or IIIA flammable or combustible liquids that are used or stored in normally closed containers or systems pressurized at 15 pounds per square inch gauge (103.4 kPa) or less.

Jesse

4/7/2023 09:31:06 am

The Control Area and the associated MAQs become moot at H3 I believe.

Matt

4/7/2023 09:39:22 am

The big concern now is the building's allowable area. Group H-3 occupancies maximum areas are very small unless the building is a IA type of construction.

Jake

4/15/2023 04:03:41 am

Hey! thanks for your answer (also to everyone else). Can you advise what is the maximum allowed area? where would you find these criteria?

Jack

4/10/2023 08:24:42 am

Something to keep in mind, specifically for storage of flammable/combustible liquids, is the requirements in 5704.3.7 and 5704.3.8 (2021 IFC). Once you exceed certain quantities, you need to store the liquids in a liquid storage room or liquid storage warehouse. There are a few more requirements to consider for these spaces.

Just an AHJ

4/10/2023 09:25:46 am

I agree with the comments above. I recommend consulting with the AHJ. You are going to want to ensure they have the resources to contain a fire situation in the proposed building. Also this sounds like an expensive build...you don't want to get too far in before the AHJ comes along and says "no way". I'm sure they would be willing to work with you but they should have an idea early on of the hazard you are bringing to their community and ensure they are ready to respond if needed. The last thing you want to do is have them find out after the fact and leave the new building owner trying to figure out how to move forward with their operations.

JSimma

4/13/2023 09:02:47 am

Assuming items are on the first floor, why not create 2 control areas? Each of which can have up to the maximum MAQ. Ground floor allows for up to 4 control areas. Each with up to 480 gallons of Class I-B Flam Liq for sprinkled and in rated storage cabinet. So 2 control areas, each with 480 gallons would get the total volume to 960 gallons. Or 4 control areas that are just sprinkled without rated storage cabinets would be 240 per control area x 4 = 960 gallons for the story. See IBC 414.2.2 table (2018 IBC) for control areas

Mark Harbison

2/24/2024 04:51:42 pm

If a rated control area MAQ is exceeded and it becomes an H-3 per code, then does the occupancy that the control area/room is located now become an H-3 occupancy as well?

What is MAQ for a High Hazard H-3 Occupancy?

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