[Chemistry Class Notes] Halon Pdf for Exam

Have you ever wondered which compound is used in fire extinguishers? What is its composition? What are its types and the chemical properties it serves? 

The answer to all these questions is halon, which is a fire suppression agent and a chemical compound that is used by firefighters. 

The National Fire Protection Association claims it is a clean agent, however, the production of Halons has been restricted. The key reason behind this is that it does not conduct electricity, which leads to no residue and further a high potential of ozone depletion, contributing to global warming. 

In accordance with the Montreal Protocol and the US Environmental Protection Agency, the production of halon was ceased on January 1, 1994, and since, its use has been decreasing constantly. 

What is Halon Gas? 

Halon gas is a chemical compound used in fire extinguishers. The major use of this compound is firefighting. Halon meaning a group of organohalogens compounds. The halon formula majorly contains bromine and fluorine along with one and two carbons. It is liquefied and compressed gas. Halons are effective in fire extinguishers with their action of interruption in the chain reaction, which leads to propagation of the combustion process. The three elements required for the fire to sustain are heat, fuel, and oxygen. When these actions are disrupted, the fire does not sustain. The properties of halon extinguisher are listed below:

• These are non-conductors of electricity

• They are used to fight fires with flammable liquids and solid combustible materials

• These are ineffective on fuels that have their own oxidizing agent

• The most favored Halon for fire extinguishers is Halon 1301 which involves electronic equipment. The key reason is that it leaves behind no residues and does not lead to damage to any electrical equipment. 

• Halon gas examples are Halon 1211 and Halon 1301. 

• These act as both greenhouse gases and depleters of atmospheric ozone.

Effect of Halon Gas on Humans

Halon does not have any major negative effects on humans making it safe to use around humans. It can also be used in occupied and closed spaces. The systems of Halon suppression became popular because of their low toxicity and chemical stability. Due to its stability, it does not damage any documents or valuable assets. The halon compound used in fire extinguishers still serves military applications. 

Availability of Halon

There are two key sources where halon gas is available from where the fire suppression system can be recharged. The first one is distributors which contain specifically stored halon for sale. The second source of Halon is through a Halon bank. After the decision of phasing out, Halon was taken, the formation of Halon Alternatives Research Corporation (HARC) took place in 1989. A recycling code of practice was created by them which lead to the provision of guidelines allowing them to recycle Halon in a safe and environmentally responsible manner. 

Replacements for Halon Gas

Halons 1301 and 1211 are excellent gases used for fire extinguishers. However, the only drawback is that they have the potential of ozone layer depletion and also contribute towards global warming. So, for the replacement, alternatives were developed which are clean agents. 

The major elements which act as Halon alternatives are 3M Novec 1230 and FM-200. They serve benefits and usage similar to Halon, alongside, are safe to use inside closed spaces. They also leave no residue. The advantage that both these elements have over Halon is that they have an Ozone Depletion Potential of 0, causing no harm to the ozone layer. 

Another replacement for Halons can be carbon dioxide. However, it is not as efficient because it displaces oxygen which suppresses the fire. There are several other halon replacements that are available in the market and are widely used.