Fire protection innovation
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.
The search continues
For a number of years after withdrawing its first halon-replacement product from the market, 3M had no clean agent offering available for sale. But 3M continued researching a next-generation halon replacement.
“We kept publishing papers,” says John Schuster, business development manager, 3M Electronics Markets Materials division, “kept active in industry organizations, stayed on the committees — even when we didn’t yet have a viable product. People in the fire protection industry kept asking us why we were still there, and the answer was: we were looking for a viable, long-term replacement for halon and HFCs. And we remained confident that someday we’d find it.”
Throughout the 1990s, 3M researchers evaluated hundreds of compounds with the goal of finding one that would serve as a viable alternative to halon. Success, however, proved to be elusive.
Finally, in 1999, a new materials team at 3M was reviewing candidate chemistries for a wide variety of applications that traditionally used ozone – depleting substances or HFCs. The team was going through a list of fluoroketones and started to brainstorm ideas for other uses of the material — when one of the team members suggested that a particular compound, C6 fluoroketone, might have potential as a clean extinguishing agent. This was a radical notion.
For a number of reasons, ketones had been largely overlooked by other clean agent manufacturers in the search for alternative halon replacement technologies. For example, hydrocarbon (hydrogen-containing) ketones, commonly used as industrial cleaning solvents, are flammable. And certain fluorinated ketones are toxic. Neither characteristic suggests their suitability as clean agents.
C6 fluoroketone, however, was a different animal altogether. Paul Rivers, advanced fire protection specialist, 3M Electronics Markets Materials division laboratory, took the material passed on by the new materials team, tested it, and found that it did indeed extinguish fires involving a variety of fuels and scenarios. It was an eye-opening discovery.
As they started learning more about this unique compound, 3M realized that C6 fluoroketone could be the halon-replacement solution for which the industry had been looking so long. They gave the commercialized version of the compound its own name: 3M™ Novec™ 1230 Fire Protection Fluid.
“There are five key properties that must be met for any candidate to be considered a sustainable replacement for halons and HFCs,” explains Mr Rivers. “It must be a clean agent. It must extinguish fires quickly, and be safe at normal-use concentrations so it can be used in occupied areas. The environmental profile must be outstanding — because that’s the only reason halons were phased out. And it needs to be commercially viable. Novec 1230 fluid satisfies each requirement.”
Testing showed that Novec 1230 fluid extinguishes fires as well as, if not better than, other halon alternatives now on the market. Moreover, because its use concentration is much lower than its No Observable Adverse Effects Level (NOAEL), Novec 1230 fluid provides the widest safety margin of any viable halon replacement.
The best news was saved for last. “We already knew that Novec 1230 fluid had zero ozone depletion potential, and we suspected that it had a low global warming potential, as well. But we were extremely pleased to learn how much lower it was than every other fluorinated halon replacement on the market.”
Whereas halons have GWPs in the range of 1300-6900, and HFCs have GWPs ranging from 3500-12,000, independent tests showed that the global warming potential of Novec 1230 fluid is 1, about the same as naturally occurring carbon dioxide. This is unprecedented for a fluoromaterial.
Released into the atmosphere, Novec 1230 fluid quickly breaks down, resulting in an atmospheric lifetime of just five days, compared to 11-65 years for halon, or 29-260 years for HFCs.1
Because of its favorable environmental and toxicity profile, Novec 1230 fluid has been approved by the US EPA for use in commercial and industrial total flooding systems and streaming applications, and is the only halon alternative approved for industrial use without restrictions.
Novec 1230 fluid is a liquid at room temperature. But 3M researchers discovered that it rapidly changes to a gas when discharged through a nozzle. It floods the room and extinguishes the fire by drawing off the heat necessary for combustion, after which it dissipates, leaving no residue. And because it is stored as a liquid, it is easy to handle and ship, and takes up less storage space than many gaseous halon replacements.
The years of searching for a long-term, viable halon replacement, rather than an intermediate solution, had paid off. 3M formally introduced Novec 1230 fluid in 2001 at the National Fire Protection Association industry tradeshow.
Today, approved systems designed for use with Novec 1230 fluid are available from leading fire protection equipment manufacturers, who have installed thousands of such systems around the world. In a relatively short period of time, several hundred metric tonnes of Novec 1230 fluid now protect critical installations such as archives, data centers, engine rooms on marine vessels, and many more, reducing the GWP of the installed base by several billion lbs of CO2 , compared to the potential releases had HFCs been used.
Without question, increasingly stringent environmental regulations continue to drive the halon replacement market. Global warming concerns are putting the viability of some clean agent alternatives, such as HFCs, in doubt. Will they be banned as halon was? Will use restrictions or the potential future costs associated with greenhouse gas emissions make the use of agents with high global warming potentials onerous or economically unfeasible?
Because of these concerns, specifiers, manufacturers and installers of clean agent fire protection systems today must take into consideration not only extinguishing performance but the long-term sustainability of the technology.
“Particularly in a large new installation, the cost of the agent is not all that significant, compared to the cost of piping, detection and alarm systems and other components,” says Mr Schuster. “What no one wants is to have their customers told that their five year-old system will have to be replaced because their extinguishing agent is being regulated out of use.”
Mr Schuster maintains that society’s demand for more environmentally responsible fire protection has been a positive force that is driving technological innovation.
“Today, competition in the fire protection industry is not just about protecting lives and property; it’s about protecting the environment as well. To me, that’s a sure sign of progress.”
Footnote: 1 IPCC (Intergovernmental Panel on Climate Change), Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change[Houghton, J.T., Y. Ding, D.J. Griggs, M. Noguer, P.J. van der Linden, X. Dai, K. Maskell, C.A. Johnson (eds.)]. Cambridge University Press, Cambridge, U.K., and New York, USA, 881 pp., 2001.