Using a Dry Chemical Fire Extinguisher

A dry chemical fire extinguisher is one of the many types of fire extinguishers used in various fire emergencies. The different classes and types of fire extinguishers as per Australian Standards have been covered in a previous article and this guide will specifically talk about the workings of a dry chemical fire extinguisher. 

To deal with unexpected fire situations, it is important to know how a dry fire extinguisher functions, how to identify it, what are its different types, how to clean up after use, and how to ensure its fire safety maintainenance and testing.

Due to fire extinguishers' low cost and high effectiveness, they are readily available across Australia. Fires can become immensely dangerous in minutes and threaten your life and property, so having a portable dry chemical powder fire extinguisher nearby in case of emergencies is crucial. 

What Colour Band Identifies a Dry Chemical Fire Extinguisher?

All fire extinguishers in Australia are an iconic red colour with a coloured band. Red catches the eye quickly, allowing for easy identification. 

Dry chemical powder fire extinguishers [DCP] are most commonly identified by their white colour band wrapped around the upper half of the cylinder. The white band is thick and easily noticeable from a distance, along with the type of extinguisher mentioned in bold writing.

If you look at the tank's description label, you will find other ways to identify a dry chemical extinguisher. There are three main details that can distinguish a dry chemical fire extinguisher:

• Sizes: 
  • Portable: 0.75kg, 1kg, 1.5kg, 2kg, 2.5kg, 4.5kg, & 9kg 
  • Mobile: 25kg & 50kg
• Easy-to-use instructions.
• Labels for Materials that you can use the extinguisher on.

What Are the Different Types of Dry Chemical Fire Extinguishers?

Australian dry chemical fire extinguishers classify under two types: BE fire extinguishers & ABE fire extinguishers. Both fire extinguishers possess similar qualities, one being able to do a little more. 

BE

BE fire extinguishers can extinguish class B & E fires. Although the type doesn't label F in its name, the powder fire extinguisher can do its job for F class fires under certain circumstances as well. However, for class F fires, a wet chemical fire extinguisher is most recommended. 

• Class B fires could spark from flammable liquids [e.g. petrol, liquid paint, turpentine, kerosene, diesel]. 
• Class E fires refer to electrical fires [e.g. from computers, electrical equipment, switchboards]. 
• Class F fires are caused by cooking oil or fat at high temperatures [e.g. in fryers and stovetops]. 

ABE

ABE fire extinguishers perform the same function as BE fire extinguishers but can put out class-A fires too. Class A fires stem from other flammable materials and carbon based solids such as plastic, textiles, paper, wood and cardboard.

This type of dry chemical extinguisher will not resolve:

• Class C fires [from flammable gases] 
• Class D fires [from combustible metal substances]
• Class F fires [cooking oils and fat]

Class B & E fires can also be put out by carbon dioxide fire extinguishers, while class A fires do well with water fire extinguishers. 

Using the wrong firefighting method could worsen the situation, increasing the risk of exposing yourself  to more danger, so make sure to learn the use cases for a dry chemical powder fire extinguisher correctly. 

How Does a Dry Powder Fire Extinguisher Work?

Before we break down how dry powder extinguishers work, it is important to understand and be fully aware of the key elements that give life to a fire. 

Any firefighter or fire safety expert will tell you that there are three components to a fire:

1. Oxygen - an element in abundance that is highly reactive with fuel.
2. Fuel - any gas, liquid, or solid that is combustible.
3. Heat - all fuel has a flash point, allowing the fire to gain power once the desired temperature is reached. 

The goal is to remove one of these key components to contain and eventually distinguish a fire. 

In terms of ABE dry powder fire extinguishers, they operate thanks to a distinguishing agent of monoammonium phosphate [MAP]. MAP is a chemical compound consisting of ammonia and phosphoric acid. When this substance is applied to a fire, it spreads quickly, melting over the flames. Think of it as a fire blanket spreading the agent along the fire, suffocating it from any more oxygen. In case of class B fires, the extinguisher impacts the base of the fire and blocks vapours that further reduce the fire.

Unlike ABE extinguishers, BE extinguishers spray a different fine powder that does not melt which is why they can not be used against class-A fires. 

One thing to note is that the fine powder is easily carried by air movement, giving way to the fire and its ability to reignite. When firefighting and using powder fire extinguishers, always pay close attention.

Cleaning Up After a Dry Chemical Fire Extinguisher

It is necessary to be cautious of any discharge effects of fire extinguishers. 

Fire safety guides recommend using extinguishers carefully when in tight spaces as it could cause a cloud of powder, obstructing your vision. Also, cover your mouth and avoid inhaling any chemicals, as they could irritate your throat and nose. 

When cleaning up the powder residue, leave no particles behind, as any leftovers could be corrosive and cause damage to certain materials. 

After using DCP fire extinguishers, you should follow these tips for cleanup:

• Do not wash any powder or other chemicals down the drain, as they are hazardous to the environment.

• To remove the powder, sweep it, vacuum it, or wipe it up using paper towels. 

• Once you remove all powder from the area, enclose the paper towels or material into a separate trash bag to be disposed into the waste bin.

Maintenance of Dry Chemical Fire Extinguishers

When it comes to fire extinguisher testing, it is required to conduct routine servicing of all your fire extinguishers every six months. As per regulation, each extinguisher should have a maintenance tag marking its most recent inspection.

Local Australian fire services recommend discharging and recharging your dry fire extinguishers, and conducting hydrostatic testing every five years.

Before every use, shake your fire extinguisher to ensure that the powder hasn't consolidated at one end of the container over time. Shaking before using will increase the effectiveness of your extinguisher. 

Ensure you safely store your extinguisher in an easy-to-reach location away from fire hazards.

Remember to never dispose of a fire extinguisher in your regular waste. Instead, your extinguishers should always be properly recycled with the help of your local fire department or by contacting your area's fire extinguisher recycling and disposal services. 

Prioritise Fire Safety

Dry chemical powder fire extinguishers are high-quality and high-performance extinguishers and understanding extinguisher types to eliminate fires could become the difference between life and death. 

That being said, firefighting is a dangerous activity, and you should always take action carefully and after receiving formal training.

Reach out to fire safety services in Geelong to maintain regular inspections, conduct extinguisher testing, and follow best practices regarding fire extinguisher use to ensure the safety of people and places.