Determining the Maximum Allowable Quantity (MAQ) of a Hazardous Material
Which code or standard applies to hazardous materials? How much of a particular hazardous material can be stored or used? What floor of the building can that hazardous material be stored or used on? These are all questions some are faced with daily. There is an assumption that people, such as facility managers, building owners, and first responders, just inherently know when a material is a hazardous material. And, that once they know it is a hazardous material, they know how to deal with that material properly and safely. We have seen the potential impacts of materials that are improperly stored or used such as in the 2013 fire and explosion at West Fertilizer Company in Texas. How can we prevent incidents like this from happening?
This blog will focus on determining the maximum allowable quantity (MAQ) for a hazardous material per NFPA 1, Fire Code and NFPA 400, Hazardous Materials Code. The eight-step process outlined here, is just one way to determine the MAQ.
Step 1: Determine hazardous material classification
The first step in identifying the Maximum Allowable Quantity (MAQ) is to determine the category of the hazardous material. NFPA 400 divides hazardous materials into 14 different categories. Using the definitions within the Code, the category or categories of the material must be determined. A hazardous material may fall into more than one category. It is also important to acknowledge that there are additional types of hazardous materials that fall outside the scope of what is intended to be covered by NFPA 400 and thus Chapter 60 of NFPA 1. This includes things like:
- Flammable and combustible liquids that have no other health hazard covered by NFPA 400 (instead see NFPA 30)
- LP-gas storage or utilization systems (instead see NFPA 58 or NFPA 59)
- Storage and use of aerosol products (instead see NFPA 30B)
For additional information related to classifying a hazardous material, check out this blog.
Step 2: Determine occupancy classification
Next, we need to determine the occupancy classification of the area where the hazardous material is going to be stored or used. Different occupancies modify the MAQs so, once we determine the MAQ per the general MAQ table (Table 188.8.131.52.1.3 of the 2021 Edition of NFPA 1), we will need to consult the other appropriate paragraphs (184.108.40.206.2 through 220.127.116.11.5) to see if that quantity is modified in any way. An excerpt of the general MAQ table can be seen below in step 4.
Step 3: Determine how the material will be used
The next variable that needs to be determined is based on how the material is going to be used. There are two main ways the material could be used. It could be stored, or it could actually be used. The storage use is intended for those instances where a hazardous material is entering the building in a container, cylinder, or tank and will not be removed from the original container, cylinder, or tank. If the hazardous material is being used, you must then identify whether it is being used in a closed system or an open system.
A closed use system designation means that, under normal conditions, the hazardous material will not be open to the atmosphere and will be kept within a container, a pipe, or equipment that does not allow vapors to escape into the air. Closed use and storage have very similar risks and are treated the same with respect to MAQ.
An open use system designation means that the process involves pouring or dispensing into an open vessel, open mixing, transferring, or processing of a hazardous material that is exposed to the atmosphere. This type of activity is considered the most hazardous and, therefore, is most restricted with respect to an MAQ.
Step 4: Determine base maximum allowable quantity
The next step is to determine the MAQ. The term "maximum" can be misleading because there are certain conditions that would allow higher amounts of material to be used or stored. The term "MAQ" really means the maximum amount of a material that is permitted in a control area before requiring additional protection. So, it's not really a "maximum", rather a threshold before additional protection requirements would need to be applied.
NFPA 1, the Fire Code, has a couple different MAQ tables which are copied from NFPA 400. The applicable table will depend on the occupancy you are in. Generally speaking, you would start with the general MAQ table (Table 18.104.22.168.1.3) and then see if/how the occupancy specific sections modify the table. In the case of a laboratory that is a business office, the code states you are to use the amounts from Table 22.214.171.124.1.3 without using the modifications found in 126.96.36.199.2.
In order to best explain how the table and associated footnotes work, we will walk through an example. The space is used as a laboratory but is considered a business occupancy. There are two different hazardous materials. One is classified as an organic peroxide class I and will only be stored. The other will be used in an open system and is classified as water-reactive class 2.
Organic Peroxide Class I
Using the table, the MAQ for an organic peroxide class I that is to be stored as a solid is 16 lbs (7.26 kg). However, looking at the table there are two applicable footnotes. Applying these footnotes is explained in the next step.
Water Reactive Class 2
Using the table, the MAQ for a water reactive class 2 material that is to be used in an open system is 10 lbs (4.54 kg). However, looking at the table there is one applicable footnote. Applying this footnote is explained in the next step
Step 5: Apply footnotes
Once the base MAQ is determined from the table, adjustments to the MAQ should be made based on the applicable footnotes. Returning to our example:
Organic Peroxide Class I
Per the table 16 solid lbs (7.26 kg) of a class I organic peroxide are permitted. However, footnote a allows 100% increase where the hazardous material is stored in an approved cabinet, gas cabinet, exhausted enclosure, gas rooms explosive magazines, or safety cans, as appropriate for the material stored. The second footnote, b, allows for a 100% increase if the building is equipped throughout with an automatic sprinkler system. These increases can be used in conjunction with each other as noted in the footnotes.
This means the MAQ will depend on what additional features are provided.
If the material is not stored in an approved cabinet or similar container and there is no sprinkler system, then the 16 lbs(7.26 kg) from the table stands as the MAQ.
If the material is going to be stored in an approved cabinet or other similar container, but the building is not sprinklered then the MAQ is 32 lbs (14.54 kg).
This would also be the MAQ if the building was sprinklered but the material wasn't going to be stored in an approved cabinet or other similar container.
If the material will be stored in an approved cabinet or other similar container and is in a building equipped with an automatic sprinkler system, then the MAQ is 64 lbs. The original MAQ is 16 lbs (14.52 kg). This is allowed to be increased by 100% because of the use of an approved cabinet:
Then that new MAQ, 32 lbs (14.52 kg) is permitted to be increased by 100% because the building is protected throughout with an automatic sprinkler system. This results in an MAQ of 64 lbs (29.04 kg):
Water Reactive Class 2
Per the table 10 solid lbs (4.54 kg) of a class 2 water reactive material is permitted. There is only one applicable footnote which allows a 100% increase if the building is equipped with an automatic sprinkler system.
In this case if the building has a sprinkler system the MAQ would be 20 lbs (9.08 kg):
If the building does not have a sprinkler system, then the MAQ remains 10 lbs (4.54 kg).
Step 6: Adjust Based on Control Area Location
As I mentioned earlier, the term "MAQ" really means the maximum amount of a material that is permitted in a control area before requiring additional protection. A control area is a building or portion of a building or outdoor area within which hazardous materials are allowed to be stored, dispensed, used, or handled in quantities not exceeding the MAQ. It is possible to have multiple control areas per floor depending on where in the building the control areas are located. The table below can be found in NFPA 1 (and NFPA 400) and dictates how many control areas are permitted per floor depending on the location within the building. This table also identifies the required fire resistance rating for the fire barriers that separate the control area from other control areas and what percentage of the MAQ is permitted based on the location within the building. It is important to note that the fire barriers are required to include floors and walls as necessary to provide complete separation. You'll notice that the further, vertically, from grade, the control area is, the higher the required fire resistance rating is for the separation of control areas and a lower percent of the MAQ is permitted in each control area. This is because the vertical distance increases the time required for emergency responders to reach the incident and increases the difficulty in controlling and resolving it.
Returning to our example, the floor ceiling assembly between the 1st and 2nd floor is a fire barrier with a 1-hour fire resistance rating. Therefore, these can be considered two separate control areas.
MAQ Floor 1: The MAQ for floor 1 is permitted to be 100% of the MAQ per control area. Therefore, 64 lbs ) of class I organic peroxide is permitted and 20 lbs (9.08 kg) of class 2 water reactive material is permitted.
Organic peroxide class I:
Water reactive class 2:
MAQ Floor 2: The MAQ for floor 2 is permitted to be 75% of the MAQ per control area. Therefore, 48 lbs (21.78 kg) of class I organic peroxide is permitted and 15 lbs (6.81 kg) of class 2 water reactive material is permitted.
Organic peroxide class I:
Water reactive class 2:
Step 7: Determine if Design is Acceptable
The last step is to determine if the proposed design and amounts is acceptable based on the MAQ identified and control area location.
Returning to our example, our building requires the storage of 150 lbs (68.1 kg) of class I organic peroxide and the open system use of 12 lbs (5.45 kg) of a class 2 water reactive material in both locations. To determine if our design of one control area on floor 1 and one control area on floor 2 with no additional protection is acceptable, we must compare the amounts of hazardous materials present with the MAQs.
Floor 1: Remember, the MAQs for floor 1 were 64 lbs (29.04 kg) of class I organic peroxide and 20 lbs of class 2 water reactive material. The 12 lbs (5.45 kg) of class 2 water reactive material is acceptable. However, the 150 lbs (68.1 kg) of class I organic peroxide exceeds the MAQ of 64 lbs (29.04 kg). This means a change to our design is necessary. One option is to provide additional protection (see the next step for more information on this). The other option would be to provide additional control areas on the same floor, if permitted per Table 188.8.131.52.1. It is important to remember these additional control areas would need to be separated from each other by fire barriers. In the case of the first floor up to 4 control areas containing 64 lbs (29.04 kg) of the class I organic peroxide are permitted. Therefore, adding two additional control areas and properly separating them would permit the storage of up to 192 lbs (87.17 kg). If the additional control areas are added, then the Protection Level 2 requirements need not be applied.
Floor 2: Remember, the MAQ for floor 2 were 48 lbs of class I organic peroxide and 15 lbs of class 2 water reactive material. The 12 lbs (5.45 kg) of class 2 water reactive material is acceptable. However, the 150 lbs (68.1 kg) of class I organic peroxide exceeds the MAQ of 48 lbs (21.78 kg). Again, this would require a change to our design. Looking at Table 184.108.40.206.1 we see that only 3 control areas are permitted on floor 2. This means that only a total of 144 lbs (65.38 kg) would be permitted on floor 2. Either, we need to add the fire barriers to create the additional control areas and store 6 lbs (2.72 kg) less than what was originally planned, or we need to add additional protection (see the next step for more information on this).
Step 8: Apply additional protections, if necessary
If the amount of hazardous material cannot be accommodated based on the number of permitted control areas and the MAQ of those control areas, then additional protection is required. There are 5 different protection levels outlined in the code ranging from Protection Level 1 to Protection Level 5.
Protection Level 1 is the highest level of protection. The only way to provide a greater level of protection is to prohibit additional hazardous materials at the site or to move the hazardous materials to a detached building. This protection level is required when high hazard Level 1 contents exceed the MAQ. These materials are unstable and can pose a detonation hazard.
Protection Level 2 is designed to limit the spread of fire from materials that deflagrate or accelerate burning. Additionally, the protection features are designed to limit the potential for fire to spread from an outside source and affect the hazardous materials in the building.
Protection Level 3 is one of the most common protection levels encountered in the general inspection of storage and industrial operations that use hazardous materials. These types of operations and storage facilities normally operate with amounts of hazardous materials greater than the MAQ while conducting business. The protection features should be understood in detail, and the amounts of hazardous materials should be reviewed due to their frequent presence within most jurisdictions. Features for
Protection Level 1 through Protection Level 3 are intended primarily to provide protection from physical hazards.
Protection Level 4 is intended to mitigate the acute health hazards resulting from the storage, use, or handling of high hazard Level 4 materials. These contents include corrosives, highly toxic materials, and toxic materials. The objective is to protect evacuating occupants and arriving first responders from being injured by these hazardous materials.
Protection Level 5 applies to semiconductor fabrication facilities.
Returning to our example, the class I organic peroxide is considered a high hazard protection level 2. Therefore, if the MAQ is to be exceeded then the requirements for Protection Level 2 must be followed. The general requirements for this (and all) protection level(s) can be found in Chapter 6 of NFPA 400. In addition to chapter 6, the appropriate chapters from 11-21 need to be consulted as well as the building code. Examples of additional requirements include required separation of occupancies, shorter travel distance limits and common path of travel limits, and more restrictive requirements relating to the number and access of means of egress. For example, the travel distance limitation for a Protection Level 2 area is 100 ft and the common path of travel is 25 feet. These would generally be more restrictive than what the building code or life safety code would say for a business occupancy. In addition to chapter 6, chapter 14 would need to be reviewed as it has requirements for organic peroxide and the building code.
This 8-step process is just one way to approach determining the MAQ. It is important to remember that they type of hazardous material, whether the material is going to be stored or used, the occupancy classification, and the location of the control area all impact the MAQ. This means that any proposed change to the material, or the location of the material should be carefully evaluated to ensure quantities still fall below the MAQ, or the necessary additional protection requirements are met. If you are looking for more information on classifying a hazardous material or the applicability of NFPA 400 be sure to check out my other blogs.