Hazardous materials are often present in manufacturing facilities of many industries. The presence of hazardous materials in and around buildings and facilities has the potential to cause serious adverse consequences in several areas, such as:
- Employee Safety: Hazardous materials can directly harm the health and safety of employees if improperly handled and/or stored. This could be in the form of hazards such as fire and explosion, acute health effects from overexposure to toxic or corrosive materials, long term health effects from prolonged exposure to materials which have impacts on health even if the material is not considered toxic; and many other potential issues.
- Physical Safety: Improper storage/handling of hazardous materials can also result in damage to facilitiesfrom fire and explosion. While this can be caused by easily identifiable hazards such as flammable liquids, there is also danger from less obvious sources such as combustible dusts, oxidizers, water reactive materials, and incompatible materials.
- Environmental Impacts: Uncontrolled or improper release of hazardous materials can obviously have detrimental environmental impacts on air and water quality. This can also have serious impacts on health and safety of people in surrounding areas and result in serious regulatory consequences.
While risks related to hazardous materials can never be fully eliminated, they can be controlled and mitigated through proper engineering and administrative controls. Among these controls is ensuring your facility is designed to the proper occupancy classification per the applicable codes. This article briefly explores hazardous materials, code limits on their storage and use in facilities, and implications to facility design and occupancy classification. Central to this discussion are codes such as the International Building Code (IBC), which govern facility design and operation. The IBC and related codes (such as the International Fire Code) address hazardous materials and related issues regarding their storage and use. It is important for facility owners and operators to have an understanding of these topics in order to maintain safe and code compliant operations.
What is a Hazardous Material?
The IBC states the definition of a hazardous material as: “Those chemicals or substances that are physical hazards or health hazards as classified in Section 307 and the International Fire Code, whether the materials are in usable or waste condition.” There are numerous categories of hazardous materials, each with its own specific definition and sub-categories. Some of the categories are:
- Flammable Liquids
- Combustible Liquids
- Combustible Dusts
- Water Reactives
- Inert Gases
- Toxic/Highly Toxic Materials
Each category of material has a different Maximum Allowable Quantity (MAQ), which will be further explored later in the next section. As an example, flammable liquids and combustible liquids can both readily cause fire and/or explosion and are of the same physical state (liquid) – however a flammable liquid has a lower flashpoint and is more volatile than a combustible liquid, and is generally considered more hazardous. Therefore a flammable liquid has a lower MAQ than a combustible liquid. Similarly, flammable liquids are further subdivided into various classes, and those that have lower flashpoints and boiling points have a lower MAQ.
Some hazardous materials are easily identifiable, while others are not. Below are a handful of examples of hazardous materials from a few different categories:
Limits on Storage and Use (MAQ)
As mentioned earlier, each type of hazardous material has a Maximum Allowable Quantity (MAQ). We will now discuss MAQ’s further with examples and implications of exceeding the MAQ.
The MAQ’s listed in the IBC limit the amount of each type of hazardous material in a facility that are in storage, and in use in open systems or closed systems. These MAQ’s vary with the type of hazard; and in some cases, the MAQ can be increased with the presence of fire sprinklers and appropriate storage. For example, the baseline MAQ for Class IB Flammable Liquids (such as Isopropyl Alcohol) in open use is 30 gallons. If the building is equipped with a code compliant automatic sprinkler system, the MAQ is doubled to 60 gallons. The baseline MAQ for storage of the same liquid is 120 gallons, which is increased to 240 gallons with an automatic sprinkler system and can be doubled again to 480 gallons if stored in ‘approved’ containers or exhausted enclosures. Note that in a situation where both storage and closed use are present, the total quantity cannot exceed the amount allowed for storage. In this example, if 60 gallons were in open use, then an additional 420 gallons could be stored (480 minus 60). These amounts are not vast quantities depending on the scale of an operation. 60 gallons is slightly more than the common 55 gallon drum size often used for transportation and storage of liquids, and 480 gallons is essentially two pallets worth of material.
Does this mean that more than 480 gallons of Isopropyl Alcohol can never be stored/used within a building? The answer is no – it is possible to have additional quantities of material. One method to increase the amount and still comply with code is through the use of Control Areas, which essentially divide a building into different compartments through the use of fire barriers. Each Control Area can then contain up to the MAQ of hazardous materials. However, a building cannot be infinitely subdivided into more and more control areas to keep increasing the MAQ – there is a limit of four control areas per building. Also, both the MAQ limits and number of control areas decrease if either above or below the first story of a building. For example, on the second story, the allowable hazardous material quantity is 75% of the baseline MAQ; with subsequent stories having lower limits.
The other method to increase the amount of hazardous materials in a building is through the use of Hazardous Occupancies (H-Occupancies). The next section touches on H-Occupancies and related design implications.
Hazardous Occupancies and Other Design Considerations
The IBC defines different occupancy groups based on the construction and use of a facility. Some of the occupancy groups in the IBC include Assembly, Business, Educational, Factory, and Storage. Most manufacturing facilities would typically be in the Factory group. Each occupancy group has specific requirements regarding construction and building systems. If a facility requires the use or storage of hazardous materials above the MAQ however, a portion (or all) of the facility would likely need to be a Hazardous (H) Occupancy. Within H-Occupancies, there are five groups – H-1, H-2, H-3, H-4, and H-5. H-1 is typically used for explosives. H-2 and H-3 are typically for Flammable and Combustible Liquids, Oxidizers, Water Reactives, and several other categories of materials. H-4 is for Corrosive and Toxic materials. H-5 is specifically used for semiconductor fabrication and similar facilities; and has specific limits for hazardous materials which differ from other occupancies.
Why is this important? An H-Occupancy can drive the requirement for many features not present in other occupancies. Some examples include high ventilation rates, secondary containment to contain a spill from a hazardous material container and sprinkler water discharge, emergency generator power for ventilation systems, higher fire ratings of barriers separating occupancy groups, separation of incompatible materials, shorter existing distances, and larger distances to lot lines and adjacent buildings. The IBC does have exceptions where an MAQ can be exceeded without the need for an H-Occupancy based on specific facility types and uses. These exceptions typically do not apply to manufacturing facilities and therefore are not in the scope of this article. It is very important to understand if an H-Occupancy is required during the design or modification of a facility or manufacturing process. If a facility needs to be converted to an H-Occupancy after initial construction, it can be prohibitively expensive; and even impossible in some cases.
Another design consideration relates to Hazardous Area Electrical Classification. The presence of flammable/combustible materials can drive the need for Hazardous Are Electrical Classification to prevent fire and explosion. There are three types of classifications: Class 1 relates to flammable gases and vapors (including vapors liberated from evaporating liquids), Class 2 relates to combustible dusts, and Class 3 relates to combustible fibers. If these hazards are present in sufficient concentrations, electrical devices and wiring in the area must be appropriately rated for the environment. Examples of this include intrinsically safe and explosion proof devices. An intrinsically safe device limits the energy available to that below what is required to cause ignition, this often means preventing sparking and keeping temperatures low. An explosion proof device is one that contains an internal explosion such that it does not ignite surrounding gases, vapor, dust, or fibers. Though Hazardous Occupancies and Hazardous Area Electrical Classification share a common thread of flammable and combustible materials, they are somewhat distinct. It is very possible to have quantities below the MAQ (and therefore not require an H-Occupancy), but still require a Class 1 electrical classification.
Inert materials such as gaseous or liquid nitrogen can also pose a hazard. Though these materials cannot burn, explode, or cause other physical hazards; they can displace oxygen resulting in oxygen deficient environments that can lead to asphyxiation. In such situations, oxygen monitoring may be required to alert personnel that oxygen levels are too low. Some processes may liberate oxygen, which could cause fire/explosion hazards as oxygen is an oxidizing gas and can promote ignition of combustible materials. In these cases, sensors may need to be installed to monitor high levels of oxygen.
The hazards and considerations described here are only some of the issues that can be caused by hazardous materials. Each situation must be evaluated carefully to understand the appropriate measures to be taken.