Understanding The Numeric Ratings On Fire Extinguishers

Understanding The Numeric Ratings On Fire Extinguishers

(2-A:10-B:C Rating ??)

All extinguishers capable of extinguishing class A, B or F fires carry a fire rating which is indicated by a number and letter (e.g. 13A, 55B). The number is indicating the size of fire it can extinguish under test conditions. The larger the number, the larger the fire it can extinguish

When it comes to fire safety, understanding the numbers on fire extinguishers is like decoding a secret language. In this blog, we're going to demystify how those numbers work and what they mean for different types of fires. So, let's dive into the world of fire safety ratings and learn how to decode those numbers, turning them into practical knowledge that could save lives.

Fire Classes

Before we jump into the numeric ratings, let's do a quick refresher on the different classes of fires:

1. Class A:

Involves everyday combustibles like wood, paper, and cloth.

2. Class B:

Encompasses fires fueled by flammable liquids such as gasoline and oil.

3. Class C:

Involves electrical fires, ignited by electrical equipment and appliances.

4. Class D:

Relates to fires fueled by combustible metals like magnesium.

Understandings Numeric Ratings

Fire extinguishers come with both letter and numeric ratings, serving as crucial indicators of their capabilities. Let's break down the numeric ratings and see how they work for different classes of fires.

1.    Class A Rating:

The number next to the "A" reflects the extinguisher's effectiveness compared to a specified amount of water. Higher numbers mean a greater capacity to handle Class A fires. Rating numbers range from 1 to 10: possible ratings are 1A, 2A, 3A, 4A, 6A, 10A , those numbers relate to the fuel load of wooden crib used during testing. The higher the number, the greater the fuel load of the test fire.

• 1-A Rating: Suitable for smaller ordinary combustible fires.
• 5-A Rating: Equipped to handle larger fires involving wood and similar materials.

Class A Test fires shall be regarded as extinguished if there are no flames visible 3 min after the complete discharge of the extinguisher.

2.Class B Rating:

The number next to the "B" indicates the extinguisher's effectiveness against flammable liquid fires. A higher number signifies a more substantial ability to suppress Class B fires. Rating numbers range from 2 to 80: possible ratings are 2B, 5B, 10B, 20B, 30B, 40B, 60B, 80B, those numbers relate to the fuel load of flammable liquid (n-heptane or hydrocarbon solvent) used during testing. The higher the number, the greater the fuel load of the test fire.

Examples include:

• 2-B Rating: Effective for smaller flammable liquid fires.
• Equipped to tackle more extensive flammable liquid fires.

3.Class C and Multipurpose Ratings:

Numeric ratings aren't typically assigned to Class C fires (electrical fires). However, when you see a "C" on the extinguisher, it indicates its suitability for electrical fires.C fires do not come with a rating number: the rating test simply determines if the extinguisher is capable of extinguishing a liquid propane gas test fire.

Multipurpose extinguishers often carry both A and B ratings along with a "C" designation, offering versatility.

For example:2-A:10-B:C Rating: Effective for ordinary combustibles, flammable liquids, and electrical fires.

Examples in Action:

1. 3-A:40-B:C:

This multipurpose extinguisher is your all-in-one solution, capable of handling ordinary combustibles, larger flammable liquid fires, and electrical fires.

1. 10-A:80-B:C:

Another versatile option with higher numeric ratings, suitable for more extensive ordinary combustible fires, substantial flammable liquid fires, and electrical fires.

 

2.    D Fires Number Rating: combustible metals

D fires do not come with a rating number: these are typically tested to international standards.

3.    E Fires Number Rating: electrical equipment

E fires do not come with a rating number: the rating test simply determines if the extinguisher is capable of extinguishing an electrically energized equipment.

4.    F Fires Number Rating: 

cooking oilsnumbers range from 1 to 4: possible ratings are 1F (0.07m²), 2F, 3F, 4F (0.5m²), those numbers relate to the surface area of the pan or tray used during testing (with sunflower oil). The higher the number, the larger the test fire.

 

Understanding Capacity and Coverage

Numeric ratings go beyond fire classes; they provide insights into an extinguisher's capacity and coverage. Higher Class A ratings mean broader coverage for ordinary combustibles, and higher Class B ratings indicate more effective suppression of flammable liquids.

Keep in mind that numeric ratings don't stand alone; the size of the extinguisher matters too. A smaller extinguisher with a higher rating can offer similar coverage as a larger one with a lower rating.

Conclusion:

In conclusion, understanding the numeric ratings on fire extinguishers empowers us to make informed decisions during a fire emergency. Whether it's a small wood fire, a spill of flammable liquid, or an electrical mishap, these numbers guide us to the right tool for the job.So, the next time you come across those digits on a fire extinguisher, remember they are your key to unlocking its potential. It's not just about numbers; it's about being prepared and proactive, ensuring the safety of yourself and those around you.