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published on

December 2022

Significant safety concerns in many work sites include accidents resulting in fires and explosions. Even with preparation and training — accidents happen. Electrical equipment that an industrial organization relies upon to get their work done can cause the ignition of flammable vapors resulting in catastrophic destruction. Thus, work site areas may be classified as “hazardous” if flammable gases, combustible liquids, combustible dust, or flammable vapors may be present and could easily be ignited by the electrical equipment. A method of analyzing and classifying potentially hazardous areas, Hazardous Area Classification (HAC) or Electrical Area Classification, is required to minimize the potential explosion risk in these installations. However, despite being a necessary step in the building process, several misconceptions regarding HAC are worth clearing up.

What is a Hazardous Area Classification, and why is it necessary?

Anyone involved with building an operating plant that contains flammable hazards knows the plant should be built following current codes, standards, and designs to ensure long-term operation under known safety risks. Minimizing these risks is the primary objective of the Hazardous Area Classification analysis — identifying and classifying regions, spaces, and locations within a facility that handles flammable/combustible material. By accurately classifying potential hazards, industrial installations can effectively minimize risk, thus mitigating possible damages.

The starting point often begins with a focus on the “Fire Triangle,” a concept wherein combining the triangle’s three sides — oxygen, a flammable fuel source, and an ignition source — will result in a fire. Removing either the fuel or the ignition source may dramatically reduce the probability of a fire, but that isn’t always a practical solution. Any given industry involving hazardous materials may use those materials in everyday processes alongside ignition sources in the form of electrical equipment or hot surfaces.

Hazard Area Classification helps identify hazardous materials and ensure that equipment in these areas is designed appropriately. Generally, different process materials and process operations will necessitate different electrical equipment designs.

What are 5 myths about Hazardous Area Classification?

Myth #1: The only reason to perform a Hazardous Area Classification analysis is to comply with relevant codes. Once done, it does not need to be updated.

While it is necessary to comply with relevant codes, compliance isn’t the only reason to perform a Hazardous Area Classification analysis. Understanding where flammable/combustible material leaks are likely to occur and controlling ignition sources in and around those areas leads to a safer work environment. As changes are made in the facility, HAC boundaries may be affected. Adding equipment and modifying process conditions, even if all are rated for the same classified area, may alter the classification. It is essential to revalidate from time to time so that potential ignition sources in hazardous classified locations are known, documented, and controlled safely.

Myth #2: There is only one standard/recommended practice when it comes to Hazardous Area Classification.

Many individual countries have set standards they adhere to, but there are also several different standards for HAC. For example, in the U.S., the hazardous location classification system is defined by the National Fire Protection Association and American Petroleum Institute — these are the standards on which OSHA is based. In Canada, the Canadian Electrical Code is used. In Europe, there are standards from the International Electrotechnical Commission (IEC), British Standards (BS), and ATEX (a certification derived from Atmosphères Explosibles).

Hazardous Area Classification Standards

While it is by no means comprehensive, a list of standard examples can be found below:


U.S. Standards

Combustible dust that could be hazardous and lead to fires or explosions

Myth #3: Only liquids and gasses must be considered in Hazardous Area Classification.

Combustible liquids and flammable gasses may most often come to mind as the primary hazardous materials needing classification, but combustible dust and flyings are also ignitable and, therefore, capable of explosion. There are dozens of dust explosions in the U.S. every year, occurring in industries ranging from chemical to food and beverage. Combustible dust can be dangerous and unpredictable and should also be considered in the classification. A beneficial pairing to a HAC analysis is often a Dust Hazard Analysis (DHA), a systematic process used to improve plant safety by identifying the specific combustible dust hazards associated with a process. Conducting these two in tandem can help a company better understand how the dust is generated and where it is likely to accumulate.

Hazardous Area Classification experts working on location

Myth #4: There is only one way to develop Hazardous Area Classification contours.

Traditionally, the methodology used to determine HAC has been conservative, classifying a unit’s boundaries without accounting for scenario-specific operating conditions. This approach often leads to a conservative HAC, ultimately increasing capital costs without providing a corresponding benefit in risk reduction. A scenario-based system, however, is another option that is often more thorough. For example, reviewing and analyzing each potential release source in a process area creates integrated classification contours to achieve a more holistic overall classification contour. This integrated unit/area contour is tailored to the equipment layout and process conditions instead of blanketing an entire process block based on the most conservative classification in the area.

A hazardous area with a thermal or fire hazard

Myth #5: Light fixtures, switches, and other smaller electrical devices don’t need to be rated for the hazardous area in which they are located.

As previously stated, when considering the “Fire Triangle,” a key component is an ignition source. While unassuming, light fixtures, switches, and other smaller electrical devices are, under the right circumstances, capable of functioning as one such ignition source. Motors, relays, and switches produce heat and arc during normal and abnormal operation. Typically, this arc is of no concern, but when surrounded by a flammable vapor, the arc acts as a source of ignition and might cause a fire or explosion. Therefore, these smaller electrical installations should be considered as a part of the entire process and taken into consideration when classifying a hazardous area.

Hazardous Area Classification is a requirement from a regulatory and safety perspective as an effective means of ignition prevention around flammable and combustible materials. Aside from being a requirement, HAC helps create safer work environments and should be performed whenever the facility is updated to ensure current classifications.

The application of regulatory standards depends on the country and the local requirements, as well as the standards guide on how to perform HAC. However, the approach to developing these contours and implementation of the standard depends on the end user. By understanding HAC, users can be better equipped to ensure their industrial environments are as safe and efficient as possible. Contact BakerRisk today for a free 7-day trial of our hazardous area classification software.