In the hands of trained personnel, portable fire extinguishers are the first line of defense against incipient fires, but in order to be useful they need to be accessible. This blog tackles the topic of portable fire extinguisher placement, both how portable fire extinguishers should be distributed and exactly where they are allowed to be placed.
The first step is to choose the correct extinguisher based on the fire risk. Extinguishers are broken down into the following ratings:
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- Class A: Ordinary Combustibles
- Class B: Flammable Liquids
- Class C: Energized Electrical Equipment
- Class D: Combustible Metals
- Class K: Cooking Media
The distribution of portable fire extinguishers is a balance between having an extinguisher nearby when you need it but not being overly burdened by the cost and maintenance of having excessive extinguishers. Let us start off with what NFPA 10 Standard for Portable Fire Extinguishers requires.
When NFPA 10 addresses extinguisher placement it uses the term “maximum travel distance to extinguisher”. This means that at any point inside the building you should never have to travel more than the maximum distance to reach an extinguisher. It is important to ensure the distance being measured is the actual distance a person would need to walk to get the extinguisher (as shown in Figure 1) and that occupants are not expected to walk through walls.
The maximum travel distance is often the limiting factor but for certain Class A extinguishers there is an additional floor area limitation. This maximum floor area that a single extinguisher can cover is directly related to the numerical A rating and level of hazard occupancy but reaches a maximum of 11,250 ft2. It is important to know both the maximum travel distance and floor area per extinguisher since you need to follow the most restrictive of the two. The following table, along with Table 6.2.1.1 and 6.3.1.1 of NFPA 10, will help you determine the required travel distance and maximum floor area.
Let’s look at a specific example of a 6-A rated fire extinguisher in an ordinary hazard occupancy. The maximum floor area is calculated by multiplying the maximum floor area per unit of A by the numerical A rating, which gives us the following:
This means that although the maximum travel distance is permitted to be up to 75ft, if you were in a wide open area such as a large warehouse you wouldn’t be able to take advantage of the entire 75ft travel distance because of the limitations that the 9,000ft2 maximum floor area would present. Check out the table below for a maximum floor area reference guide for Class A extinguishers.
Let’s look at another example of an extinguisher with enough of an A-rating to have a 11,250 ft2 maximum floor area, one might think you could space the extinguishers every 150 ft since you would be 75ft from either extinguisher if you were in the middle, but because most rooms are rectangular this creates gaps where you would be further than 75 ft from an extinguishers (see sad faces in the figure below).
Instead, portable fire extinguishers should be placed every 106 ft. to take advantage of the coverage area per extinguisher and conforming to the shape of most rooms (see Figure 4 below). This of course assumes that there are no dividing walls that would impede the path to an extinguisher.
If Class A extinguishers are placed at the limit of their maximum travel distance then people might have to travel the entire 75 ft to get the extinguisher and then back another 75 ft to return to the fire in order to extinguish it. Let’s say the average person travels 3.5 mph, this means it would take them 30 seconds to travel the 150 ft it could take to grab the extinguisher and get back to the fire. A lot can happen in 30 seconds.
When distributing portable fire extinguishers an additional level of complexity is added when walls, obstructions and other structural features that limit movement are taken into consideration.
Placement
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Extinguishers need to be located along normal paths of travel. This is because extinguishers should be available to occupants when evacuating. You do not want occupants to move away from an exit and risk being trapped by the fire when trying to retrieve an extinguisher. Extinguishers also need to be installed in places where they’re visible, but if an obstruction is unavoidable then there needs to be a sign provided to indicate the extinguisher’s location.
Installation height
Extinguishers need to be installed at least 4 inches off the ground up to a maximum of 5ft. The exception to this is for extinguishers heavier than 40 lbs, they can only be up to 3 ft 6 inches off the ground and wheeled fire extinguishers don’t need to be off the ground since the wheels already keep the cylinder from touching the floor.
Cabinets & Hangers
Extinguishers not on wheels are often installed on hangers or brackets, which need to be intended for the extinguisher, but they can also be installed in cabinets.
Conclusion
In my humble opinion portable fire extinguisher distribution and placement is the trickiest part of installation. There is a balance between efficiency and practicality that truly make a difference in the event of an emergency. I hope everyone found this helpful, let us know in the comments below what you think the toughest part of the job is.
For more information check out our NFPA Portable Fire Extinguisher Fact Sheet. Annex E of NFPA 10 also has some more great information on fire extinguisher distribution if you want to learn more about the topic.
Editor’s Note: I rounded to the nearest whole number for any calculations performed in this blog.
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