Throughout history, water has been mankind’s primary defense against the ever-present threat of fire. Technology for applying water to fire hazards remained fairly primitive until 1852, when the first manually operated, perforated pipe sprinkler systems were installed in textile mills. Automated water sprinklers began to appear in the 1870s and by the middle of the 20th century were widely used in commercial buildings. It seemed that fire was at last on its way to being tamed.

Then the electronics age threw everything into disarray.

As computerized record keeping began to replace manual systems, it became apparent that a new kind of fire extinguishing agent was needed to replace water, which was highly destructive of sensitive electronics and digital storage media. In addition, new kinds of facilities – controlled by electronics – had begun to assume many of the critical functions of industry, the military and other institutions. These facilities needed to remain in continuous operation, even in the event of fire, to avoid catastrophic interruptions. Examples of these ‘special hazards’ include communications centers, process control rooms, data hubs and airport control towers.

In some applications, CO2 could be used as an extinguishing agent; however, at normal use concentrations for extinguishing fire, CO2 is toxic to humans and consequently not suitable for occupied spaces.

Then, in the late 1940s, scientists introduced what they thought would be the ultimate weapon for special hazards fire protection: halon.

Halon is a gaseous material that acts as a ‘clean extinguishing agent’, meaning that it is electrically non-conductive, evaporates completely and leaves no residue that can damage sensitive devices or valuable documents. Halon is a highly-efficient fire extinguishant that is also low in toxicity, so it was widely used to protect normally occupied spaces.

The problem with halon is that it has a very high ozone depletion potential – which is why in 1991, after the Montreal Protocol imposed a worldwide production ban on halons and other ozone-depleting substances, the fire protection industry went shopping for a more environmentally acceptable replacement for halon. This proved to be more difficult than many had imagined.

Over a 10-year period, a number of halon alternatives were introduced, but all had major shortcomings. Some were high in toxicity; some had high global warming potentials (GWPs) and long atmospheric lifetimes; others exhibited performance characteristics that were unacceptable. 3M, which has more than 40 years of experience in the fire protection industry and is a world leader in the development and manufacture of advanced fluoromaterials, found that its own first-generation perfluorocarbon halon replacement had a relatively high GWP and is no longer commercially available.

Among this so-called ‘first generation’ of halon replacements, a class of chemicals called hydrofluorocarbons (HFCs) eventually emerged as the most widely adopted alternative technology.

Although non ozone-depleting, HFCs have high global warming potentials and long atmospheric lifetimes. Because of this, HFCs could one day face severe regulatory restriction, and possibly even an outright ban, as happened with halons.

That concern is based on the observation that global environmental regulation has shifted its focus away from ozone depletion toward the issue of global warming, and to the reduction of ‘greenhouse gases’ (GHGs), thought to be a major cause of global warming and climate change. As international agreements like the Kyoto Protocol continue to push for reduction in the emissions of GHGs, it is becoming obvious that none of the traditional halocarbon clean agents will be immune from future regulation.