Fire Sprinkler Hazard Classifications Defined

Fire sprinklers fall into a range of hazard categories or class. The fire sprinkler hazard classification used in designing a sprinkler system has to be determined before the design work starts. This will aid in determining the traits of the fire sprinkler installation. The traits will determine the number of sprinklers, the specification of water supply, and the number of fire pumps, among other things such as placement

The classifications are dependent on the building’s occupancy and use, and they include light hazard, low hazard, ordinary hazard, moderate hazard, high hazard, and severe hazard. Read on to learn more about each of these classifications below.

Please note that these examples are only examples; each building will vary slightly in what is stored and used there, so only a fire safety consultant can say for sure what your business’s classification would be.

Light Hazard

These are locations where combustible products and the quantity of Class A combustibles and Class B flammables are incredibly unlikely. Class A combustibles include paper, refuse, and fabrics among others, while Class B flammables include flammable liquids.

In these environments, possible fires have a relatively minimal rate of heat release. Some of the light hazard areas may consist of hospitals, educational institutions, meeting rooms, libraries (aside from massive stack rooms), nursing homes, residential areas, auditoriums and theatres (aside from prosceniums and stages), seating areas in restaurants, offices, and data processing.

Low Hazard 

These are locations where combustibility and the quantity of Class A combustibles and Class B flammables are low. Any fire that develops here would increase at a moderate rate and have moderate heat release rates.

Examples of buildings in this category include armories, bakeries, beauty salons, barber shops, doctors’ offices, canneries, wineries, foundries, breweries, office buildings, and municipal buildings.

Ordinary Hazard 

These hazard areas are environments where the combustibility and quantity of Class B flammables and Class A combustible materials are moderate. You can expect fires to grow with moderate heat release rates in these environments.

Some businesses and environments that constitute an ordinary hazard are malls, light manufacturing or research operations, parking garages, workshops, automobile showrooms, electronics plants, laundries, restaurant service areas, drink manufacturing, or maintenance/service areas.

Moderate Hazard

Buildings in this category are seen as Moderate hazard locations. Here, combustibility and quantity of contents are moderate. Any fire that began in one of these environments would most likely develop fast and have a moderately enhanced rate of heat release.

Some examples of moderate hazard buildings include dairy barns, cold storage warehouses, manufacturing and clothing plants, amusement occupancies such as an arcade, farm equipment sheds, machine shops, some restaurant commercial kitchens, unoccupied buildings, and certain machine shops.

High Hazard 

Buildings in this category are viewed as High Hazard occupancies. Buildings in this category have a high content of combustibility and quantity, so if a fire started here  it would likely rapidly develop and have an enhanced heat release rate.

Some buildings that are commonly classified as high hazard environments are department stores, stables, barns, feed stores, freight terminals, pulp and paper mills, wharves and piers, and warehouses storing paint, furniture, or paper.

Severe Hazard 

These are locations where the combustibility and quantity of class A combustible material is enhanced. The amount of Class B flammables in these locations are also quite high. Any fires that began in these locations would spread quickly and burn incredibly hot, making them difficult to put out.

Some of the buildings that commonly require the severe hazard fire sprinkler classification are boat or aircraft service terminals, storage warehouses, sawmills, metal extrusion factories, aircraft hangars, particleboard and plywood production, rubber manufacturing, and textile manufacturing. To ensure you are on the right track when it comes to selecting and designing your sprinkler system, speak with a fire safety consultant. These professionals can make specific recommendations and help expedite your permitting process.

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