The maximum allowable quantity per control area is specified in Tables 5003.1.1(1) through 5003.1.1(4) of the IFC. Tables 5003.1.1(1) through 5003.1.1(4) establish the maximum quantities allowed in a control area (see Section 5003.8.2 for design and protection requirements). If the quantity of chemicals used in a building does NOT exceed the maximum allowed per control area AND the number of control areas does NOT EXCEED the number and percentage of chemicals allowed by Table 5003.8.3.2, those areas are considered part of the main use and do NOT have to meet all of the requirements for a hazardous occupancy.
TABLE 5003.1.1(1)
Table 5003.1.1(1) is subdivided based on whether the material is in storage OR in use in a “closed” or “open” system. Definitions of both “Closed” and “Open” systems are found in Section 202. Within these subdivisions, the appropriate MAQ is listed in accordance with the PHYSICAL STATE (solid, liquid or gas) of the material. A column for gas in “open systems” is not indicated because gaseous hazardous materials should NOT be allowed in a system that is continuously open to the atmosphere. Note that the third column of the table, “Group When the Maximum Allowable Quantity Is Exceeded,” is informational ONLY, since occupancy group determination is within the scope of the International Building Code (IBC), not the IFC.
Note also that the MAQ values for gases are indicated (at the head of each gas column) as being “at NTP,” i.e., at a “normal” temperature of 70°F (21°C) and a pressure of one atmosphere, or 14.7 pounds per square inch absolute (psia) (101 kPa). In other words, the MAQs for gases are based on a certain volume of free gas, NOT gas under pressure in its cylinder.
able 5003.1.1(1) and Table 5003.1.1(3) for outdoor storage include a row for inert gases and inert cryogenics, thus clarifying that the amount of inert gases and inert cryogenics in storage or use is unlimited. There is also a definition in Section 202 for “Inert gas” that provides a means of classifying gases considered inert. This definition ensures that inert compressed gases, inert cryogenic fluids or gas mixtures containing cryogenic fluid are properly classified.
Even though the quantity of inert gases and cryogenics is NOT limited inside of a building, they are still subject to regulation. For example, storage of inert gases and cryogenic fluids requires an operational permit in accordance with Sections 105.6.9 and 105.6.11, respectively.
In addition, Section 5307 has requirements for a mechanical ventilation system designed and operated in accordance with Section 5004.3 for storage and Section 5005.1.9 for use when a room or building contains INERT compressed gases.
Rooms containing inert cryogenic compressed gases ARE REQUIRED to comply with the construction and mechanical ventilation requirements in Section 5504.2.
The unit of measure for liquefied gases has historically been incorporated into the MAQ tables in terms of gallons (L) because that has been the conventional thinking. From a practical standpoint, the use of gallons (L) as a unit of measure for liquefied gases introduces an inconsistency into the concept due to the fact that, unlike most liquids, the density of liquefied gases varies widely.
In commerce, liquefied gases are packaged and distributed based on weight as the unit of measure. Table 5003.1.1(1) has been revised to reflect threshold quantities in terms of the units of measure that are readily available from the commercial market and greatly simplifies the use of the code, thereby making it more user friendly. The revision required that a model be used as the basis for comparison. This approach was taken when thresholds were revised to base certain health-hazard threshold levels using a “chlorine index” as the model. A similar approach was used as a means to simplify the use of the table.
In the case of liquefied FLAMMABLE GASES, probably the most commonly encountered liquefied gas is LPgas (LPG). LPG, as defined, can consist of propane, butane, propylene or others either in a mixed or pure form. NFPA 58, Table B.1.2(a), lists the approximate densities of commercial propane and butane at 60°F (16°C) as 4.20 and 4.81 pounds per gallon, respectively. Converting the 30-gallon (114 L) quantity to pounds and rounding up to the closest 5 pounds (2.3 kg) yields a quantity of 150 pounds (68 kg) on a weight basis. The density of butane is greater than that of propane, therefore representing the worst case where mixtures of propane and butane are
involved. The result of converting the 30-gallon (114 L) threshold to a 150-pound (68 kg) threshold is in keeping with the philosophical approach used with gases, such as ammonia and chlorine, as they appear in Table 5003.1.1(2).
The threshold level of 15 gallons (57 L) for oxidizing gases is now expressed in terms of weight based on using any of a number of oxidizing gases as the baseline. However, given the fact that a single cylinder of CHLORINE (an oxidizing, corrosive and toxic gas) has been used as the baseline in Table 5003.1.1(2), it is reasonable to use a single cylinder of chlorine as the baseline for the establishment of quantity in Table 5003.1.1(1), as well. To test the assumption, a comparison was made to the 1,500-cubic-foot (42 m3) baseline maximum quantity for a non-liquefied gas using oxygen as the model. Using a specific volume for oxygen of 12.1 cubic feet per pound translates the 1,500 cubic feet (42 m3) allowed for the baseline MAQ to 125 pounds (57 kg) if this gas was considered on a weight basis. The use of 150 pounds (68 kg) as a baseline quantity for liquefied oxidizing gases resolves the problem where a single cylinder of chlorine would not trip the Group H-4 occupancy threshold, but would trip the Group H-3 occupancy threshold where arguably the inherent health hazards of the gas may represent a greater concern for public safety than do the physical hazards of the same gas.
It is recognized that this approach may appear to represent a major increase in the threshold for liquefied oxidizing gases; however, it brings the threshold levels into parity with those of liquefied flammable gases, which may represent the greater hazard given the potential for fire and/or explosion. The example using oxygen as the baseline shows that an increase is justified and establishes a clear rationale that is based on practical examples of materials commonly found in commerce, which have generally been accepted for use as the threshold for an increased level of control. In addition, the use of weight as a unit of measure brings the code into correlation with units typically used by the suppliers of these products, thereby mitigating the need for elaborate conversions into units of measure not found in common use.
Note a refers the user to Section 5003.8.3 to determine if a design strategy using the control area concept is needed for a building to avoid being classified in Group H.
Note b clearly indicates that the aggregate quantity of hazardous materials in use and storage, within a given control area, cannot exceed the quantity listed in the table for storage.
Without Note c, many common alcoholic beverages and household products containing a negligible amount of a hazardous material could result in a Group M occupancy being classified as a high hazard. Note c also recognizes the reduced hazard of the materials based on their water miscibility and limited container size. A similar exception is indicated in Table 5003.1.1(2), and in IBC Tables 307.1(1) and 307.1(2).
Notes d and e of the table are significant in that, for certain materials, the MAQ may be increased due to the use of approved special hazardous material storage methods as listed in the note, an approved automatic sprinkler system, or both. The notes are intended to be cumulative in that up to four times the base MAQ may be allowed per control area, if the building is sprinklered and approved special storage methods are used, without classifying the building as Group H. While the use of approved special storage methods is not always a feasible or practical method of storage, they do provide sufficient additional protection to warrant an increase if utilized to contain the entire MAQ (not just the increase amount). For example, the tabular MAQ for the storage of Class IA flammable liquid is 30 gallons (114 L) and both Notes d and e apply. Applying the notes accumulatively, the increased MAQ becomes 30 X 2 = 60 X 2 = 120 gallons (454 L). Note e also requires that a safety can, when used for increasing the MAQ of flammable and combustible liquids stored or used indoors, be a listed metal safety can meeting the requirements of UL 30, as required by Section 5003.9.10 (also see the commentary to that section).
The code recognizes the relative lower hazard of Class IIIB liquids as compared to that of other flammable and combustible liquids by classifying them as Group H-3 and by establishing a base MAQ of 13,200 gallons (49 962 L). As indicated in Note f, the quantity of Class I oxidizers and Class IIIB liquids, without classifying the occupancy as Group H-3, would not be limited, provided the building is fully sprinklered in accordance with NFPA 13. The hazard presented by Class I oxidizers is that they slightly increase the burning rate of combustible materials that they may come into contact with during a fire. Class IIIB combustible liquids have flash points at or above 200°F (93°C). Motor oil is a typical example of a Class IIIB combustible liquid.
Note g recognizes that the hazard presented by certain materials is such that they may be stored or used only inside buildings that are fully sprinklered.
Note h clarifies for the user that while there is a combination MAQ for flammable liquids, no individual class of liquid (Class IA, IB or IC) may exceed its own individual MAQ.
Note i allows for a special quantity of inside combustible liquid storage in tanks that are connected to a fuel-oil piping system in accordance with Section 603.3.2. This would apply to most oil-fired stationary equipment, whether in industrial, commercial or residential occupancies. Oil-fired heating equipment and diesel engine-driven generator sets and their fuel supplies are indicative of the types of fuel-oil piping systems to which this note would apply.
Note k permits a larger amount of Class III oxidizers in a building when used for maintenance and health purposes. The quantities proposed are reasonable for occupancies such as the health care industry where Class III oxidizers are used for maintenance purposes, sterilization and sanitation of equipment and operation sanitation. The method used to store the oxidizers is subject to the evaluation and approval of the fire code official.
Note l clarifies that the 125 pounds (57 kg) of storage permitted for consumer fireworks represents the net weight of the pyrotechnic composition of the fireworks in a nonsprinklered building. This amount represents approximately 121/2 shipping cases (less than one and one-half pallet loads) of fireworks in a nonsprinklered
storage condition. In cases where the net weight of the pyrotechnic composition of the fireworks is unknown, 25 percent of the gross weight of the fireworks is to be used. The gross weight is to include the weight of the packaging.
Note n provides an exception when the amount of hazardous material in storage and display in Group M and S occupancies meets the requirements of Section 5003.11.
While cotton is included in the definition of combustible fibers, Note o recognizes the lesser hazard of cotton when it is stored in densely packed bales. See the commentary to the Section 202 definitions of “Baled cotton, densely packed” and “Combustible fibers” for further information.
Note p clarifies that vehicles and appliances with closed fuel systems should be treated no differently than machinery or equipment when applying the provisions of the table. The fuel contained within the fuel tanks of vehicles or motorized equipment is not to be considered when calculating the aggregate quantity of hazardous materials within a control area of a building. For example, when evaluating a parking garage with several hundred cars parked inside, the capacity of their fuel tanks is not counted. Also, when motorized equipment, such as a floor buffer or forklift, is stored or used, those fuels are not included as long as the other code requirements are followed. This note also allows a reasonable amount of alcoholbased hand rub for infection control and patient safety located in Group I-2 occupancies in appropriately sized dispensers to be located in control areas and permits the amounts not to be included in determining the MAQ. Section 5705.5 addresses the specifics regarding these amounts and locations.
Note q draws attention to the particularly challenging hazards of combustible dusts. This note specifies that where combustible dusts are manufactured, generated or used, and the concentration of dust or operating conditions creates a fire or explosion hazard, the building or space must be classified as a Group H-2 occupancy. To avoid this occupancy classification, the analysis needs to demonstrate why such a classification is not warranted. It should include an analysis of the material’s characteristics, and the type of engineering and administrative controls that will be employed in the process to quantitatively mitigate the risk of a dust deflagration. The basis for this determination must be documented in a technical report and opinion in accordance with Section 104.7.2 (or IBC Section 414.1.3). See also the commentary to the definition of “Combustible dust” in Chapter 2 and the commentary to Chapter 22.
TABLE 5003.1.1(2)
Table 5003.1.1(2), similar to Table 5003.1.1(1), specifies the MAQs of hazardous materials, liquids or chemicals allowed per control area before having to classify a part of the building (or the entire building) as a GROUP H OCCUPANCY and is subdivided based on whether the material is in storage OR in use in a closed or open system. Definitions of both “Closed system” and “Open system” are found in Section 202. Within these subdivisions, the appropriate MAQ is listed in accordance with the physical state (solid, liquid or gas) of the material. A column for gas in open systems is not indicated because hazardous gaseous materials should not be allowed in a system that is continuously open to the atmosphere. This table contains health-hazard materials classified as Group H-4, in accordance with IBC Section 307.6. While the materials listed in this table are considered health hazards, some of the materials may also possess physical hazard characteristics more indicative of materials classified as Group H-1, H-2 or H-3 (see IBC Section 5001.1). The MAQs listed in the table are indicative of industry practice and assume the materials are properly stored and handled, in
accordance with the code. Group H-4 materials, while indeed hazardous, are primarily considered a handling problem and do not possess the same fire, explosion or reactivity potential associated with other hazardous materials.
Note that the MAQ values for gases are indicated (at the head of each gas column) as being “at NTP,” i.e., at a “normal” temperature of 70°F (21°C) and pressure of one atmosphere, or 14.7 psia (101 kPa). In other words, the MAQs for gases are based on a certain volume of free gas, not gas under pressure in its cylinder.
The MAQ of 810 cubic feet (23 m3) for corrosive and toxic gases established in the table was based on a single cylinder of chlorine. Historically, Note g to the table that existed in previous editions of the code (but which was deleted in 2009) recognized that a single cylinder of ammonia should be allowed; however, the use of 810 cubic feet (23 m3) did not allow for this given the fact that, by comparison, a 150-pound (68 kg) cylinder of ammonia contains over 3,300 cubic feet (93 m3) of gas. The preferred solution in lieu of trying to justify or create a series of footnotes to address individual gases was to use an index system that created a standardized approach to establish the unit of measure by using a widely distributed gas, such as chlorine, as an index. However, the unit of measure in terms of weight was not carried into the table when it was formulated, thereby creating creating the need for the use of footnotes to address ammonia. Compressed gases may be in liquid form or they may be gaseous. Maintaining the use of chlorine as the index to the table for toxic and corrosive properties and listing the threshold for liquefied gases (as well as those that are nonliquefied) eliminates the need for elaborate conversions in units of measure using data that in many cases is not readily available.
The index used to establish the weight threshold is based on the use of arsine, a highly toxic gas with a specific volume of 5.0 cubic feet per pound. It may be argued that recognizing the common forms of gases, e.g., liquefied and nonliquefied, allows a de facto increase in the threshold levels applied. It is possible that one could have a toxic gas that is liquefied and also one that is nonliquefied in the same area, therefore doubling the aggregate quantity of gas if all was considered. While this is theoretically possible, it is not considered to be the norm. In addition, there is precedent in using the approach as established in Table 5003.1.1(1) for flammable and oxidizing gases. Also see the commentary to Table 5003.1.1(1) for further discussion of liquefied gas MAQ units of measure.
Note b clearly indicates that the aggregate quantity of hazardous materials in use and storage, within a given control area, cannot exceed the quantity listed in the table for storage.
Without Note c, many common household products containing a negligible amount of a hazardous material could result in a Group M occupancy being classified as a high hazard. Note c recognizes the reduced hazard of the materials based on their water miscibility and limited container size. A similar exception is indicated in Table 5003.1.1(1), and IBC Tables 307.1(1) and 307.1(2).
Where applicable, Notes d and e provide an increase in the base maximum allowable amount similar to that in Table 5003.1.1(1) [see commentary, Table 5003.1.1(1)].
Note f provides an exception when the amount of hazardous material in storage and display in Group M and S occupancies meets the requirements of Section 5003.11.
Note g of the table is significant in that, for certain materials, their hazard is so great that their MAQ may
be stored in the building only when approved exhausted enclosures or gas cabinets complying with Sections 5003.8.5 and 5003.8.6, respectively, are utilized.
TABLE 5003.1.1(3)
Table 5003.1.1(3) specifies the MAQs of hazardous materials, liquids or chemicals allowed per outdoor control area before being subject to additional regulations contained in Chapters 51 and 53 through 67, and is subdivided based on whether the material is in storage or in use in a closed or open system. Definitions of both “Closed system” and “Open system” are found in Section 202. Within these subdivisions, the appropriate MAQ is listed in accordance with the physical state (solid, liquid or gas) of the material. A column for gas in open systems is not indicated because hazardous gaseous materials should not be allowed in a system that is continuously open to the atmosphere. This table contains physical-hazard materials, as defined in Section 202. While the materials listed in this table are considered physical hazards, some of the materials may also possess health hazard characteristics, as defined in Section 202. The MAQs per outdoor control area listed in the table are indicative of industry practice and assume the materials are properly stored and handled in accordance with the code. The base MAQ per outdoor control area of 810 cubic feet (23 m3) for gases that are either corrosive or toxic is based on a standard-size chlorine cylinder. Note that the MAQ values for gases are indicated (at the head of each gas column) as being “at NTP,” i.e., at a “normal” temperature of 70°F (21°C) and pressure of one atmosphere, or 14.7 psia (101 kPa). In other words, the MAQs for gases are based on a certain volume of free gas, not gas under pressure in its cylinder.
Historically, the concept of “outdoor control areas” was introduced into the code as a means to establish a threshold where the general provisions of Chapter 50 would apply. When this table was created, the logic for assignment of threshold values was primarily based on the use of multipliers representing a multiple increase of the basic tabular values shown in Table 5003.1.1(1). In the first draft of the code, this table limited the MAQ of gaseous and liquefied flammable gases to 1,500 cubic feet (42 m3) and 15 gallons (57 L), respectively. The result was that the threshold level for liquefied flammable gases in interior areas was greater than that allowed for the same commodity when stored in outdoor areas. Assuming that the threshold level of 30 gallons (114 L) for indoor areas was correct, the value of 15 gallons (57 L) shown for outdoor areas is believed to have been in error. Code change F1324-98 increased the threshold quantities for flammable and oxidizing gases, as well as a number of other commodities, in storage in outdoor areas by a factor of 2 resulting in the increase for liquefied flammable gases from 15 to 30 gallons (57 to 114 L), furthering the inconsistency. The table corrects the MAQ inconsistency for liquefied flammable gases and, as in Table 5003.1.1(1), changes the MAQ unit of measure to units of weight rather than those of volume. This eliminates confusing and elaborate calculations, thereby bringing the code closer into harmony with the commercial environment.
The index system used to obtain a unit of measure for weight is based on multiples for a single 150-pound (68 kg) cylinder of butane for flammable gases and a single 150-pound (68 kg) cylinder for chlorine. The row for oxidizing gases provides consistency and correlates in concept with conversion to a weight basis [also see commentary, Table 5003.1.1(1)].
While hazardous materials within a closed or open system are considered to be “in use,” Note b clearly indicates that the aggregate quantity of hazardous materials in use and storage within a given outdoor control area cannot exceed the quantity listed in the table for storage.
Note c provides an exception when the amount of hazardous materials in outdoor storage in conjunction with a retail or wholesale Group M occupancy meets the requirements of Section 5003.11. The outside storage area must be under the same ownership as the Group M occupancy.
TABLE 5003.1.1(4)
Table 5003.1.1(4), similar to Table 5003.1.1(3), specifies the MAQs of hazardous materials, liquids or chemicals allowed per outdoor control area before being subject to additional regulations contained in Chapters 51 and 53 through 67. It is also subdivided based on whether the material is in storage or in use in a closed or open system. Definitions of both “Closed system” and “Open system” are found in Section 202. Within these subdivisions, the appropriate MAQ is listed in accordance with the physical state (solid, liquid or gas) of the material. A column for gas in open systems is not indicated because hazardous gaseous materials should not be allowed in a system that is continuously open to the atmosphere.
This table contains health-hazard materials, as defined in Section 202.
While the materials listed in this table are considered health hazards, some of the materials may also possess physical-hazard characteristics, as defined in Section 202. The MAQs per outdoor control area listed in the table are indicative of industry practice and assume the materials are properly stored and handled in accordance with the code. These materials, while indeed hazardous, are primarily considered a handling problem and do not possess the same fire, explosion or reactivity hazard associated with other hazardous materials.
As in Tables 5003.1.1(1) through 5003.1.1(3), a weight unit of measure has been established for liquefied gas MAQs and the table has been revised to recognize that these materials may exist in liquid, as well as gaseous form. The index system used to establish the quantity for toxics and corrosives is based on multiples of a single 150-pound (68 kg) cylinder of chlorine. The index system used to establish the threshold quantity for highly toxic liquefied gases is based on arsine, a highly toxic gas with a specific volume of 5.0 cubic feet per pound [also see commentary, Table 5003.1.1(1)].
Note b clearly indicates that the aggregate quantity of hazardous materials in use and storage within a given outdoor control area cannot exceed the quantity listed in the table for storage.
Note c provides an exception when the amount of hazardous material in outdoor storage in conjunction with a retail or wholesale Group M occupancy meets the requirements of Section 5003.11. The outside storage area must be under the same ownership as the Group M occupancy.
Note d of the table is significant in that, for certain materials, the hazard is so great that their MAQ may
be stored only when approved exhausted enclosures or gas cabinets complying with Sections 5003.8.5 and 5003.8.6, respectively, or laboratory fume hoods are utilized.
Note e states that when toxic liquids with a vapor pressure in excess of 1 psia (7 kPa) at 77°F (25°C) are stored, the MAQ is limited to the amount listed for highly toxic materials.