What Is Fire, Classes Of Fire, Types Of Fire Extinguishers And Their Uses

What Is Fire, Classes Of Fire, Types Of Fire Extinguishers And Their Uses,

What is Fire ?

Fire is a chemical reaction that involves the rapid combination of oxygen with a material, typically a fuel, accompanied by the release of heat and light. This process is known as combustion. The three essential components for fire are often referred to as the "fire triangle":

1. Fuel: This is the material that undergoes combustion. It can be solid, liquid, or gaseous. Common examples include wood, paper, gasoline, and natural gas.

2. Oxygen: Oxygen is necessary to support the combustion process. It is usually obtained from the air, which is about 21% oxygen.

3. Heat: A certain amount of heat is required to initiate and sustain the combustion process. Once the fire has started, it can generate its own heat, sustaining the reaction.

Additionally, a more modern representation of fire is the "fire tetrahedron," which includes a fourth component:

Chemical Chain Reaction: For sustained combustion, a chain reaction is needed, where the heat produced in the initial combustion reactions further enhances the availability of fuel and supports the continuous burning process.

Fire is a crucial element in human history, having played a significant role in the development of civilization. However, it can also be destructive and dangerous if not properly controlled. Understanding the principles of fire and fire safety measures is important to prevent accidents and manage its use effectively.

Classes of Fire?

In the United Kingdom, fire classifications are similar to those in many other countries and are often represented using a different system compared to the one used in the United States. The UK uses a system that includes five classes of fire, designated by letters:

Class A - Fires involving solid materials:

Includes fires involving solid combustible materials like wood, paper, textiles, and plastics.

Extinguishing agents: Water or foam.

Class B - Fires involving flammable liquids:

Involves fires with flammable liquids or liquefiable solids, such as petrol, diesel, and oil.

Extinguishing agents: Foam, dry powder, or carbon dioxide.

Class C - Fires involving gases:

Relates to fires involving flammable gases.

Extinguishing agents: Dry powder or carbon dioxide.

Class D - Fires involving metals:

Concerns fires involving combustible metals like magnesium or sodium.

Extinguishing agents: Specialized dry powder designed for metal fires.

Class E - Electrical Fires:

Involves fires that originate from electrical equipment and appliances.

Extinguishing agents: Non-conductive agents such as dry chemical or carbon dioxide to avoid electrical conductivity.

Class F or K - Fires involving cooking fats and oils:

Applies to fires in commercial kitchens involving cooking oils and fats.

Extinguishing agents: Wet chemical fire extinguishers specifically designed for kitchen fires.

It's important to follow the guidelines and standards set by the British Standards Institution (BSI) and other relevant authorities when it comes to fire safety and firefighting equipment in the UK. Fire extinguishers and other firefighting tools are often labeled with the classes they are suitable for, and it's crucial to use the appropriate extinguishing agent for the specific type of fire to ensure effectiveness and safety.

Types Of Fire Extinguishers and Their Uses

There are five main types of fire extinguishers, each designed to handle different types of fires. The classification is based on the type of fire they are effective against. The five types are:

Water extinguishers (Class A):

These extinguishers are suitable for fires involving ordinary combustibles such as wood, paper, and cloth. They work by cooling the fuel and reducing the temperature of the fire.

Foam extinguishers (Class A and B):

Foam extinguishers are effective against Class A (ordinary combustibles) and Class B (flammable liquids) fires. They create a blanket of foam that suppresses the release of flammable vapors and cools the fire.

Dry powder extinguishers (Class A, B, and C):

These extinguishers are versatile and can be used on Class A (ordinary combustibles), Class B (flammable liquids), and Class C (electrical) fires. They work by interrupting the chemical reaction of the fire and forming a barrier between the fuel and the oxygen.

Carbon dioxide (CO2) extinguishers (Class B and C):

Carbon dioxide extinguishers are effective against Class B (flammable liquids) and Class C (electrical) fires. They work by displacing oxygen, creating a suffocating atmosphere that extinguishes the fire.

Wet chemical extinguishers (Class K):

Wet chemical extinguishers are specifically designed for Class K fires, which involve cooking oils and fats. They create a soapy foam that cools the oil and suppresses the vapors, preventing reignition.

It's essential to choose the right type of fire extinguisher for the specific hazards present in a given environment. Additionally, many modern fire extinguishers are labeled with multiple classes to indicate their versatility in combating different types of fires.

Warnings of Fire Extinguishers

While fire extinguishers are crucial safety tools, it's important to use them correctly and be aware of their limitations. Here are some general warnings and considerations for using fire extinguishers on different fire classes:

Water extinguishers (Class A):

Warning: Do not use on electrical fires (Class C) or flammable liquid fires (Class B) as water conducts electricity and may spread the fire.

Foam extinguishers (Class A and B):

Warning: Avoid using on electrical fires (Class C) due to the risk of electric shock. Use in a well-ventilated area to prevent the buildup of flammable vapors.

Dry powder extinguishers (Class A, B, and C):

Warning: The discharge of dry powder can cause reduced visibility, so be cautious in enclosed spaces. It may also create a breathing hazard, so avoid inhaling the powder.

Carbon dioxide (CO2) extinguishers (Class B and C):

Warning: CO2 can displace oxygen, so avoid using in confined spaces without proper ventilation. Ensure that the fire is completely out, as CO2 does not provide a cooling effect, and re-ignition is possible.

Wet chemical extinguishers (Class K):

Warning: Wet chemical extinguishers are specifically designed for cooking oil and fat fires (Class K). Do not use them on other fire classes as they may be ineffective.

Additionally, it's essential to remember some general safety tips when using fire extinguishers:

Only attempt to use a fire extinguisher if it is safe to do so and if you have been trained in its use.

If the fire is spreading rapidly, the environment becomes unsafe, or if you are unsure about the fire class, evacuate the area immediately and call the fire department.

Remember that fire extinguishers are part of an overall fire safety plan, and it's crucial to have regular inspections, maintenance, and employee training to ensure their effectiveness in case of an emergency.

How To Use Fire Extinguisher (Pass Formula)

The PASS formula is a simple and widely used acronym to help individuals remember the steps for using a fire extinguisher effectively. PASS stands for Pull, Aim, Squeeze, and Sweep. Here's a breakdown of each step:

Pull:

Start by pulling the pin or breaking the tamper seal on the fire extinguisher. This step is necessary to unlock the operating mechanism.

Aim:

Aim the nozzle or hose at the base of the fire. It's crucial to direct the extinguishing agent at the source of the flames rather than at the flames themselves.

Squeeze:

Squeeze the handle or lever to discharge the extinguishing agent. This action releases the pressure and allows the extinguishing substance to be expelled from the extinguisher.

Sweep:

Sweep the nozzle or hose from side to side, covering the entire base of the fire. This sweeping motion helps ensure that the extinguishing agent is applied thoroughly and helps control the fire more effectively.

Remember the acronym PASS to help you recall the steps when using a fire extinguisher:

P: Pull

A: Aim

S: Squeeze

S: Sweep

It's essential to stay calm and focused while using a fire extinguisher. If the fire is not quickly controlled, or if it is spreading rapidly, evacuate the area immediately and call the fire department. Fire extinguishers are designed for use on small, manageable fires, and safety should always be the top priority. Additionally, always follow up with emergency services, even if you believe you have successfully extinguished the fire.

What Is Fire, Classes Of Fire, Types Of Fire Extinguishers And Their Uses