What is Halon? Halon Replacements

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What is Halon? Why was it replaced by modern fire extinguishing agents? Get to know the alternatives for Clean Agent systems

Aug 26, 2026

Halon was once the agent of choice in fire protection, particularly where a fire had to be put out fast and critical equipment had to survive it: control rooms, electrical systems, electronic devices, communication rooms, and any space where water or a residue-leaving agent was out of the question.

Its strengths were rapid extinguishment, no residue, non-conductivity, and safe use around electronic equipment. For its era, that made it a key fire suppression technology.

Then its effect on the ozone layer was discovered, and countries moved to control it and stop new production. The industry had to develop alternatives.

One of those alternatives now drawing serious interest is the clean agent group with ODP = 0 and low GWP, such as FK5112 / FK-5-1-12, the agent used in PAF-222 Clean Agent.

This article walks through: what Halon is → why it was replaced → what the replacements are → HFC-227ea → FK-5-1-12 → PAF-222

What is Halon?

Halon is the common name for a group of chemicals known as halogenated fire extinguishing agents, used in fire suppression because they work efficiently and put fires out quickly.

Halon has several key properties:

Extinguishes fire rapidly
Leaves no residue after discharge
Non-conductive
Can be used in areas holding electrical equipment
Disperses thoroughly throughout a room
Suits total flooding fire suppression systems
Used where water or foam would damage property

The EPA states that Halon was used in fire suppression for its efficiency, its clean agent properties, and its non-conductivity, which made it suitable for areas holding critical and electrical equipment.

That non-conductive property is still a key criterion for modern agents. Read more at What is Non-Conductive (Dielectric)?

How many types of Halon are there?

Several types turn up in fire protection, but these are the ones you are most likely to meet.

Halon 1211

Chemical name: Bromochlorodifluoromethane

Chemical formula: CF₂ClBr

Halon 1211 was used as a streaming agent, in portable fire extinguishers for instance.

Clean agents now do that work instead. Read more at Clean Agent Fire Extinguishers

Halon 1301

Chemical name: Bromotrifluoromethane

Chemical formula: CF₃Br

Halon 1301 was used in total flooding systems for enclosed spaces such as equipment rooms, control rooms, and anywhere needing automatic fire suppression.

Halon 2402

Another type of Halon, formerly used in specialised fire suppression applications.

The EPA identifies Halon 1211, Halon 1301 and Halon 2402 as Halon group substances regulated under ozone-depleting substance controls in the United States.

Why was Halon so popular in the past?

Before the environmental restrictions came in, Halon was one of the most effective agents available, because it combined several useful properties at once.

🔥 1. Rapid extinguishment Halon disrupts the combustion process chemically, which brings a fire under control extremely quickly.

⚡ 2. Non-conductive This made it suitable for areas housing electrical and electronic equipment.

🖥 3. Leaves no residue Unlike dry chemical powder agents, which can leave residue on equipment. See how the agent types differ at What is the difference between Clean Agents and Dry Chemical Powder?

🌫 4. Excellent dispersion In a total flooding system, the agent spreads evenly across the designed area.

🏢 5. Suits critical spaces Control rooms, communication rooms, computer rooms, and anywhere water cannot be used.

Those qualities are why Halon was so widely used in fire suppression before the environmental controls arrived.

So what is the problem with Halon?

For all its efficiency, Halon carries a major environmental problem: a high ozone depletion potential.

It is classified as an ozone-depleting substance (ODS) because its composition contains bromine, and in some types both bromine and chlorine, which contribute to the destruction of ozone in the atmosphere.

What is the ODP value of Halon?

ODP (ozone depletion potential) compares how much a substance can deplete ozone, with CFC-11 set as the baseline at ODP = 1.

Substance	ODP
CFC-11	1
Halon 1211	3
Halon 1301	10
Halon 2402	6

When was Halon phased out?

The phrase "Halon phased out" needs care, because in practice it does not mean every Halon cylinder worldwide was banned overnight.

In the United States, for example, the EPA states that production and import of newly manufactured Halon, or virgin halons, was phased out from 1 January 1994. Since then, Halon for specialised uses has come mainly from recovered and recycled sources.

Existing Halon systems are still in use in certain high importance applications:

Aviation
Certain military systems
Oil and gas operations
Specialised applications with no suitable equivalent alternative yet

So the more accurate statement is:

"New production of Halon has ceased, and there has been a transition toward alternative agents in many applications"

Rather than:

❌ "Halon is completely banned worldwide"

Why look for Halon replacements?

Which leads to the obvious question:

If Halon is so good at putting fires out, what can replace it?

A replacement has to hold on to what made Halon useful:

Fast suppression + no residue + non-conductive + equipment protection

While reducing the environmental impact.

The EPA states that the industry has developed and implemented a range of Halon replacements in fire suppression systems, including halocarbons, inert gases, and other agent types.

To compare the different types of clean agent fire suppression system, read more at Different Types of Clean Agent Fire Suppression Systems

Halon replacements

What is Fluorinated Ketone?

FK-5-1-12 is a clean agent developed for fire suppression, used as an alternative in total flooding systems.

The EPA identifies FK-5-1-12 as an acceptable replacement agent for total flooding systems, with ODP = 0 and GWP < 1 under the EPA's SNAP program.

For the naming, properties and practical applications of this group of agents, read more at What is FK5112 / What is FK-5-1-12, and for the GWP figures at What is GWP?

Comparing Halon with modern clean agents

Property	Halon 1301	HFC-227ea	FK-5-1-12
Type	Halon	HFC	Fluorinated Ketone
Clean Agent	✓	✓	✓
ODP	10	0	0
GWP	High	3,220*	<1*
Leaves Residue	No	No	No
Non-Conductive	✓	✓	✓
Use with Electronic Equipment	✓	✓	✓

For a detailed technical comparison between FK-5-1-12 and HFC-227ea, read more at What is the Difference Between FK-5-1-12 and HFC-227ea?

Are Halon and PAF-222 the same?

No.

Both belong to the group of agents used to protect spaces and critical equipment, but they are different substances with distinct chemical properties.

The key differences:

Halon

Contains bromine
Has ozone-depleting potential
High ODP
New production has ceased in many countries under ODS regulations

FK-5-1-12 / PAF-222

Is a fluorinated ketone
ODP = 0
Very low GWP
Used in clean agent total flooding systems

For product details, see What is PAF-222, and for a comparison with the agents in common use, What is the Difference Between PAF-222 and General Fire Extinguishing Agents?

Can PAF-222 be used to replace Halon?

It has to be considered system by system.

A new agent should never be filled directly into an existing Halon cylinder or system.

Changing a system from Halon to FK-5-1-12 means considering at least:

Room volume
Hazard type
Fuel type
Design concentration
Agent quantity
Cylinder size and quantity
Pipe size
Nozzles
Detection system
Alarm system
Pressure relief
Ventilation
Ventilation after discharge
System standards and certifications

So:

Moving from Halon to FK-5-1-12 should be a new system design or a retrofit carried out by an engineer or specialist, not a straight 1:1 agent swap.

If you currently run HFC-227ea, FM-200 or Novec 1230, read the transition guidelines at What is the Replacement Agent for HFC-227ea? and What is the Replacement Agent for Novec 1230?

Frequently Asked Questions (FAQ)

1. What is Halon?

Halon is a group of halogenated fire extinguishing agents with high suppression efficiency, leaving no residue and non-conductive, which is why they were widely used in fire suppression systems for critical spaces.

2. What is the difference between Halon 1211 and Halon 1301?

Halon 1211 was typically a streaming agent, used in portable extinguishers. Halon 1301 was used in total flooding systems for enclosed areas.

3. Why was Halon phased out?

Because it is an ozone-depleting substance with a high ODP, which puts it under the regulations protecting the ozone layer. Read more at What is ODP?

4. What is the ODP value of Halon?

Halon 1211 has an ODP of 3, and Halon 1301 an ODP of 10, according to EPA data referencing Montreal Protocol ODP values.

5. Is Halon completely banned?

It is inaccurate to say Halon is banned worldwide. In the US, production and import of newly manufactured Halon ceased in 1994, but recycled Halon is still used in certain specialised applications such as aviation and military systems.

6. What agents can replace Halon?

Several groups, including HFCs, inert gases and fluorinated ketones. The choice depends on the system type, the space, the hazards, and the project requirements. See the system types at Different Types of Clean Agent Fire Suppression Systems

7. Can HFC-227ea or FM-200 replace Halon?

HFC-227ea is one of the substances used as an alternative in systems that previously ran Halon. It has ODP = 0, but its GWP is high, so environmental regulations need to be weighed alongside it. Read more at What is GWP?

8. Can FK-5-1-12 replace Halon?

FK-5-1-12 is one of the clean agent options for total flooding systems, and the EPA lists it as an acceptable replacement with ODP = 0 and GWP < 1 under SNAP data. Replacing a system still means designing and verifying it against system standards, not simply swapping the agent 1:1.

9. What is PAF-222?

PAF-222 is a fire suppression system product using FK-5-1-12 as its primary agent, offering a clean agent option where critical equipment has to be protected and low GWP is a priority.

10. Is PAF-222 better than Halon?

It should not be called better in every respect, because each agent has different properties and limitations. FK-5-1-12 does have a clear environmental advantage, with ODP = 0 and GWP < 1 according to EPA data.