NIST Special Publication 984
ADDRESSING THE NEED FOR HALON REPLACEMENTS
Ronald S. Sheinson
Navy Technology Center for Safety and Survivability
Combustion Dynamics Section, Code 6185
Naval Research Laboratory, Washington, DC 20375-5342
USA Tel: (1-202) 404-8101; Fax: (1-202) 767-1716, Email: firstname.lastname@example.org
This paper describes some of the factors, interactions, and dynamics of evolving halon substitute
approaches and options. The viewpoint is from my experiences at the US Naval Research
Laboratory (NRL) as a bench scientist, field test director, technical program manager, DoD
Halon Alternatives Steering Group advisor, and US Government Representative and Technical
Advisor to the United Nations Environment Program’s Halons Technical Options Committee. I
have been fortunate to be an interacting part of the halon replacement process at several different
levels. The experiences and observations I describe are my own and do not represent official
viewpoints or policies.
How did halons become so prominent in fire protection?
How did halons become so prominent in fire protection? Fire losses have long occurred. With
advances in technology and mechanization the opportunity for catastrophic casualties also
increased, especially when involving large quantities of liquid fuels. Around 1948 the US Army,
sustaining tremendous losses in World War II, initiated a research review with Purdue University
searching for very efficient, less toxic, fire extinguishants. The study, which became public
later, considered approximately 60 compounds. These were mainly halogenated hydrocarbons
(thereafter labeled as numbered halons). Halons 1301, 1211, 2402 and 1202 were identified (as
were CF3I and PBr3 but both were considered likely to be more toxic). The US developed
primarily halon 1301. Europe used halon 1211 but later increasingly used halon 1301 due to
greater halon 1211 toxicity. Russia (and the former Soviet Union countries) employed primarily
halon 2402. Here, ease of manufacture was probably a consideration.
I received a telephone call in the 1980s asking about the difficulty of replacing halons compared
with replacing CFCs. I noted that the CFCs require certain thermodynamic properties to
function as refrigerants while the halons require not only thermodynamic properties but also
chemical properties to function as extinguishants. To add to the difficulty in finding
halon replacements, the chemistry needed to extinguish fires was very closely related to the
chemistry that ‘extinguishes’ the ozone layer. Further, as the ozone depletion potential of halons
were higher than those of CFCs by up to an order of magnitude, the halon replacement solutions had to
have that much more depletion potential improvement. Bottom line, halons were much more
difficult to replace than CFCs.
The phone call had been from the EPA to help formulate the US Government position on the
Montreal Protocol. Appreciating the difficulties of replacing halons for their critical life and
property protection roles, the Montreal Protocol had CFC production phase-out schedules but
only undefined future halon restrictions.
Over the years, the use of halon based fire protection systems has greatly increased.
Over the years, the use of halon based fire protection systems has greatly increased. Thus, when
the mounting evidence on stratospheric ozone layer depletion by chlorofluorocarbons (CFCs)
and halons resulted in a halon production halt, the magnitude of the problem faced in fire
protection was immense. The impact was even greater with an accelerated halon production
phase-out schedule. Production of halons was banned in the developed countries from January 1,
1994, two years before any other ozone-depleting substance production halt. What happened to
accelerate the timetable is part of the story in this paper.
In the early 1970s prior to stratospheric ozone environmental concerns, there were already
significant efforts on studying halon fire suppression. The US National Academy of Sciences
held a symposium on “An Appraisal of Halogenated Fire Extinguishing Agents” in April 1972.
Issues included toxicity aspects and practical applications of fire suppression for a variety of
scenarios. The US Naval Research Laboratory (NRL) was active in halon laboratory and field
studies as well as alternative gaseous approaches by that time. I was studying spontaneous
ignition with Fred Williams when Dick Gann was hired by NRL to work on fire suppression.
Dick assembled cup burner and small (1.8 m3) total flooding test facilities in addition to
conducting flow tube kinetic studies. He also organized an American Chemical Society
symposium on “Halogenated Fire Suppressants.” This important symposium included many
technical papers delving into understanding the mechanisms of halon suppression action. The
proceedings were published in 1975 as volume 16 of the ACS Symposium Series. When Dick
went to NIST from NRL, I was his replacement on the halon replacement efforts.
Efforts were well underway for developing a scientific understanding of suppression and
improving fire protection. NRL was actively involved in shipboard safety and survivability, and
especially fire protection. Even as early as the 1970’s halon related studies included smoldering
combustion, kinetics, cup burner exploration, quantifying physical and chemical effects,
quantifying HF and HBr from laboratory scale and full-scale extinguishments, and full- scale
total flooding system evaluation and development providing the shipboard design guidance for
Navy halon system implementation. Cup burner studies showed that halon 1301 works 20 % by
physical action and 80 % by chemical action. The 80 % halon chemical action is split between
25 % radical scavenging by CF3 and 55 % radical catalytic recombination by Br. The agent
quantification model was later expanded as a predictive tool for suppressant requirement for new
aliphatic hydrohalocarbons and complex mixtures including with physical agents varying oxygen
concentrations. The reported high CF3 suppression activity result was later used by Great Lakes
Chemical Corporation to select the molecular structure of 1,1,1,2,3,3,3-heptafluoropropane as a
promising candidate halon replacement to synthesize. The high HF production results
foreshadowed the even greater production of HF from non-brominated halon replacements. The US
military can be very proud of their very significant lead efforts in proper halon use, conservation
and halon replacement programs.
Halon Replacements: The halon replacement program at NRL
The halon replacement program at NRL included a range of tasks, representative of the mix that
is needed within the technical community in pursuing halon replacements. Understanding
combustion suppression mechanisms and being able to suggest and confirm possible highly
efficient suppressant chemicals is less than half the effort. Success only comes when acceptable
agent availability, toxicity, storage, generation, dissemination and distribution in practical
systems addressing real fire threats is achieved. Science, technology, engineering, and program
politics must all come together.
But this is getting ahead of the story. How did the need for a halon replacement arise? An
entirely different issue was the perceived need for faster transportation. One proposed solution
was to create a large fleet of high altitude supersonic transport aircraft, or SSTs. A possible
problem emerged. The combustion engines from hundreds of SSTs flying high in the
atmosphere would emit a tremendous quantity of nitrogen oxides. The NOx would react with
and destroy a significant amount of ozone in the stratospheric ozone layer. The stratospheric
ozone layer absorbed considerable ultraviolet light from sunlight. Although some UV radiation
is helpful as a germicide, a rapid change greatly increasing exposure to these energetic photons
would cause health and food bio-chain problems. A significant amount of research was initiated
on clean burning engines with congressional hearings probing the repercussions. In the end the
SST fleet was not built, but awareness to the need for and fragility of the ozone layer was
CFCs are a wonderful chemistry success story, but they would turn out to cause a serious
problem. They were invented and found to be very stable with relatively low toxicities. CFCs
quickly were adopted as refrigerant fluids replacing toxic sulfur dioxide and ammonia for many
uses. Their production increased tremendously as refrigeration, air conditioning and other usage
spread. In 1974, Mario Molina and Sherwood Roland posed an interesting question. Since
CFCs were very stable, what happened to them when they were emitted by leaks or at end of
system lifetime? They had been detected in the atmosphere. The concentrations in the
troposphere, the lower atmosphere in which we and weather exist, corresponded to production.
They must be accumulating without being destroyed. Molina and Roland proposed that CFCs
crossing the tropopause into the stratosphere would be subject to photolysis by the more
energetic UV radiation present at higher altitudes. The liberated chlorine atoms could then enter
into catalytic cycles destroying ozone. A new serious threat to the stratospheric ozone layer
emerged. Unlike the SSTs, CFCs were already in existence with increasing production.
We were aware in 1976 that the halons ...
We were aware in 1976 that the halons were at least as potent stratospheric ozone layer depleters
as were the CFCs. Dr. Homer Carhart, former Director of the Navy Technology Center for
Safety & Survivability at NRL, noted that if CFCs were bad, then halons with bromine, directly
under chlorine in the halogen column of the periodic chart, could behave similarly. Denis
Bogan, then my post-doctoral fellow, conducted approximate kinetic calculations confirming the
vulnerability. Our technical response was halon replacement research. Our long-range impact
evaluation was supplied by Homer. He felt that while the existing and probable future Navy
halon usage was insignificant compared with the total ozone depletion magnitude, perception
driven mandates would emerge in the future necessitating halon replacement. As we have seen,
the science, technology, business, environmental, and political (world-wide) concerns have
interacted to form our constantly evolving perceptions. The results have been increasingly
restrictive requirements on halon production and use. Possessing a larger picture appreciation of
total system dynamics is essential.
The potential repercussions to the stratospheric ozone layer were not appreciated. Halon usage
for fire protection increased tremendously. Systems became certified. Construction codes and
insurance companies strongly encouraged their use. In perhaps most of the instances where
halon was employed, it was not uniquely needed. But if you were a fire protection engineer
designing a system to provide protection and you chose not to employ halon, you had a hard sell
to make. You needed to spend considerable time smartly considering the needs and tailoring a
system to satisfy them. You must obtain approval from the authorities having jurisdiction,
convince the insurers of the adequacy of the system, and convince your sponsor the increased
cost of conducting business was for his good. Does one accept significant time delays,
expensive tests, and higher insurance premiums or, just install a pre-approved, one-size-fits-all,
Although the potential ozone destruction ...
Although the potential ozone destruction issue was known within the scientific community, the
lack of a general perception of the seriousness of ozone depletion had not yet arisen. While I
continued halon replacement related research, it was primarily as a low budget side project. No
mandate materialized. We knew what would occur in the future, but that is far different from
establishing its importance to others. Potential sponsors and decision makers have limited
resources and seemingly unlimited tasks to accomplish. Less important issues are ignored until
they go away – or become too important to ignore.
All during this time period, NASA had been studying the ozone layer, including satellite ozone
concentration measurements. There was not much cause for excitement. The change was to
emerge from the sky over Antarctica. There are peculiar circumstances around this frozen
continent. The large landmass at the South Pole has winds that circle the continent, essentially
isolating it from air interactions with the rest of the atmosphere. It also is very cold and in
darkness almost half a year. The known ozone destroying reactions of chlorine should have
caused only single digit percent reductions in ozone concentrations since a significant fraction of
the chlorine is tied up in forms such as ClONO2 and HCl that do not interact with ozone.
However, sunlight would break up those species into reactive forms once antarctic winter was
over. During winter the very cold air over Antarctica allowed formation of polar stratospheric
clouds (PSCs). The cloud surfaces enhanced reaction rates and tied up NO2, which would
otherwise combine with ClO to form ClONO2. When spring sunlight activated the chlorine
species while the clouds still lingered on in the warming atmosphere, dramatic ozone depletion
occurred, an unexpected phenomenon. The confluence of air currents, cold, clouds, surfaces,
sunlight, and chlorine were all necessary for the formation of what became the “ozone hole.”
If there were satellite ozone measurements over the South Pole...
If there were satellite ozone measurements over the South Pole, why was the ozone hole not seen
before the 1980s? Such dramatic drops in ozone concentration had not been expected. Thus, the
mathematical algorithms processing the data had been programmed to ignore such large
discrepancies; they must be in error. After ground based instruments reported large ozone
decreases, the satellite data was reexamined. The ozone hole was ‘rediscovered’ to have had a
33 per cent concentration decrease in 1975.
There was now an area of decreased ozone with the easily grasped image of an ozone hole.
Australians potentially would be among the most affected by increased UV radiation levels
around Antarctica. A significant happening was when an Australian pipe fitters union supported
not servicing CFC equipment. They understood CFCs cause ozone depletion and therefore cause
more UV exposure. They understood the health implications were not good. They took the only
direct action they could. Their boycott got peoples’ attention.
Public concern, and thus, legislative imperative, was increasing. US congressional hearings,
National Academy of Science reports, and US, Canada, Norway, Sweden, and European
Community actions restricting CFC usage began. A NASA plane flew into the ozone hole and
dramatically provided the “smoking gun” with concentration traces showing ozone concentration
dropped dramatically precisely where active chlorine species concentration abruptly rose.
Definition of the problem allows taking action. If they can land a man on the moon, why can’t
they make a good cup of coffee? Or solve the ozone hole problem?
The idiosyncrasies of the polar ozone hole ...
The idiosyncrasies of the polar ozone hole include the existence of the quasi-biennial oscillation.
A result of this world atmosphere phenomena means that the ozone hole is worse in alternative
years. So once every two years someone can point out that the ozone hole is much larger than it
was last year and demand action. Perceptions of complex phenomena are important drivers.
British Lord Kennet said “Politics is the art of making good decisions on insufficient evidence.”
Laws responding to the need to take some action can be shortsighted. However, in the case of
the evolving Montreal Protocol on Substances that Deplete the Ozone Layer, the politicians have
done very well with a very complex issue. Occasionally, gentle urging is required as in the form
of a Natural Resources Defense Council lawsuit brought against the US EPA to carry out US
It is truly difficult to supply sufficient evidence for scientists and legislators to make good
decisions. What are background ozone concentration levels? What are normal fluctuations?
What are the trends? Ozone depletion rates are functions of latitude, longitude, altitude, time of
year, time of day, and the concentrations (at the specific location) of reactive species and the
controlling chemistry and physics. For good measure, once in fifty to a hundred years there is a
very large volcanic eruption that inserts massive amounts of chemicals into the stratosphere. Mt.
Pinatubo in the Philippines greatly affected the world atmosphere for several years, primarily
with sulphur compounds. Natural sources for chlorine and bromine also exist from the oceans
and land life forms.
If stratospheric levels of chlorine and bromine due to man-made sources, after minimization of
unnecessary CFC and halon releases, become less than natural chlorine and bromine sources,
why impose further drastic restrictions? Because of: 1) the capability to take some action, 2) the
emotional need to do something, and 3) the capability to change the situation back towards the
previous status quo. How far to go is a complex societal decision. A viewpoint on the lack of
need for action expressed in many parts of the world was that the ozone depletion issue was a
white man’s problem. Darker skinned peoples are less susceptible to skin cancer from increased
UV exposure. The old colonial countries were perceived as trying to subjugate developing
countries by imposing economic hardships and dislocations. They would not be allowed to raise
their standards of living by utilizing established, cheaper technologies based on ozone depleting
Amazingly, despite this perception, many countries ...
Amazingly, despite this perception, many countries of the world came together in agreement and
ratified the Montreal Protocol. This took extensive negotiations, establishing what could be
established, creating constituencies, and making deals. A major ‘deal’ was establishing special
consideration for countries with economies in transition (CEITs), with a multilateral fund (MLF)
supported by developed countries to aid CEITs and less developed countries. The less developed
countries were assured sponsorship for technology transfer, allowing their economies to
transition to non-ozone depleting technologies according to a timetable to be better defined in the
The Montreal Protocol entered into force January 1, 1989. It controlled production, not use.
CFC production phase-out schedule for the developed countries was defined, with halon
production decreases to be dealt with later. Circumstances would continue to arise to hasten the
halon phase-out schedule. A sleeper issue in the treaty, and an important consideration in
evaluating approaches to the similar environmental concern of global warming, were the
undefined terms for developing countries. The CFC increases allowed for China in order to give
all its citizens the barest of food refrigeration capability dwarfed most countries’ CFC
Why were there amendments and adjustments to the Montreal Protocol accelerating the phaseout
times? Why were the halons singled out for an even faster phase-out schedule? There was
better appreciation of the ozone depletion processes, less than hoped for results of some
enactments (including clandestine production and smuggling), heightened perceptions of the
seriousness of the situation engendering the need for further actions, and for the halons, the
appearance of being able to easily have a large effect with a simple identifiable action.
As long as the highly visible ozone hole was far away over Antarctica, it was less compelling.
But increased UV over populated northern countries gave more driving concern. Once every 10
to 20 years is there a very cold winter over the artic. This is rare due to the absence of a large
land mass and a circumpolar wind phenomenon. Polar stratospheric clouds can form and remain
until late in a cold winter, perhaps until sunlight returns above the artic circle to liberate active
chlorine species and form a North Pole ozone hole. A cold winter did occur and the media did
focus on the coming North Pole ozone hole. Actually the PSCs dissipated before strong sunlight
appeared. There were new lower ozone concentration levels reached, but nothing comparable to
the Antarctica ozone hole. However, increased pressure for more rapid global action was
Halon Replacements: There is a very valid rationale to be more concerned with bromine...
There is a very valid rationale to be more concerned with bromine (and iodine) containing
compounds. Less reactive chlorine compounds can require light activation for rapid ozone
depletion. Bromine in the form of BrO has a thermodynamically allowed reaction channel that
does not require activation. Consequently bromine, and thus halons, has a greatly enhanced
effectiveness compared to chlorine. Even though chlorine atmospheric loadings are much
greater than bromine atmospheric loadings, the magnified depletion effect makes halons a
significant contributor to ozone depletion. Halons are definitely part of the problem.
Putting an exact number on potential halon damage to the ozone layer is very difficult. The
effectiveness of bromine, as for chlorine, is a function of latitude, longitude, altitude, time of
year, time of day, and the concentrations (at the specific location) of reactive species and the
controlling chemistry and physics. The controlling chemistry includes the interaction of bromine
and chlorine cycles. There is not an independent metric for bromine. Its effectiveness depends
on the concentrations of the chlorine species present at each specific location. Ozone depletion
potential (ODP) is defined relative to the assigned value of 1.0 for CFC 11. Halon 1301 has an
ODP of between 10 and 16, depending on the specific model and assumptions used in the
calculation. Models and concentration information are continually updated. Regulation cannot
function with such uncertainty. The ODP of halon 1301 was defined as 10 for purpose of legal
calculations such as taxes. This is not a scientific definition, but one allowing for political
operations. Where information is insufficient, decisions still need a basis.
Depending on location in the atmosphere and time, bromine can be far worse than chlorine, up to
a thousand times more deleterious for ozone destruction. Policy makers grasped this greatly
increased destructiveness. Halons were also a target that could be easily focused upon. CFCs
are used for a variety of purposes including refrigeration, air conditioning, foam blowers,
electronics manufacture, solvents, etc. There are many different applications in many different
industries. Halons were determined as responsible for at least ten percent of man-caused ozone
layer depletion and, simplifying consideration, it is used primarily for one purpose only, fire
protection. Only methyl bromide and its agricultural use was a bigger simple sector target. That
application was viewed (until more recently) as necessary and hard to replace.
Halon Replacements: To policy formulators trying to ‘repair’ the ozone hole
To policy formulators trying to ‘repair’ the ozone hole and minimize stratospheric ozone layer
depletion, there is an apparently simple approach with a big payoff. Halon phase-out has a
significant clearly defined benefit and with usage in one industry with clear distribution lines,
action seemed straightforward. The early phase-out of halon production became too
advantageous a path to be ignored. While production minimization of all ODSs was the goal,
halon production faced the earliest stoppage.
“If you are not part of the solution, you are part of the problem.” That dictum is too simplistic
and harsh to apply generally. Success involves having the players have a stake in the desired
outcome. Companies that manufacture halons can perhaps be involved in manufacturing
halon replacements. Their issue is not resisting phase-out, but replacing an existing product with a new
product and achieving market share. The more narrow methyl bromide sector however, did not
have an in-kind replacement product. Possible solutions were emerging from completely
different industries. Therefore resistance to regulation was strong. Fire protection companies
could perhaps adapt to new approaches, but there is the definite possibility of undesirable change
Halon Replacements: There were grave ...
There were grave concerns in the fire protection community about the dislocations the lack of
halon would cause, as well as doubts that such action was really warranted. I received many
calls along the lines, “How can they take away my halon?” “Don’t they know lives and assets
depend on it?” “The powers that be must give my use an exemption for continued production
and availability.” As I stated as a talking head in a CNN Science Watch interview, many if not
most halon usage was not absolutely necessary. Alternatives did exist. But there was some
fraction of halon use for which there were not acceptable halon replacements that were currently
technically and economically feasible. For those, including some three dimensional flammable
liquid fire threats, not having halon did mean that more lives would be lost and that assets and
the capabilities they supplied would be lost. However, continuing with halon was not
acceptable. The decision makers representing many governments of the world had already
decided the increased threat of skin cancer and potential interference with the food chain were
more critical. The calculus of the Montreal Protocol included acceptance of increased loss of
lives and property from fires as a necessary cost for preserving the ozone layer’s UV radiation
In 1988 I had a project to identify a halon 1301 replacement that would have a lower ODP by an
order of magnitude, i.e., an ODP of 1 instead of 10. CF2BrH became my exploratory candidate
and I did find a chemical source from a firm that manufactured brominated anesthetics. At a
1988 halon alternatives conference sponsored jointly by the EPA and US Air Force, I mentioned
to representatives of Great Lakes Chemical Corporation that CF2BrH might be a chemical for
their consideration. They told me they had no interest. Bob Tapscott later told me he also
recommended investigating CF2BrH around the same time. In fact Great Lakes did not want to
reveal their business position of already considering production of that compound, later trade
named by them as FM-100.
My heptane fuel cup burner studies showed about one third more CF2BrH (by gas volume) was
required for extinguishments compared to halon 1301. The ODP was approximated as 1, so the
compound had potential to satisfy the ODP improvement mandate given me. We did medium
scale (56 m3) total flooding extinguishment tests not just on CF2BrH itself, and also CF2BrH as a
minor component in a blend. An ODP value of 1 was acceptable for halon replacements only for
a short time. Employing a mixture allowed me to meet the new halon replacement criteria for an ODP
of 0.20, as well as reduce toxicity impact. We verified the low concentration in the mixture still
retained much of the chemical catalytic bromine effectiveness as predicted by our quantifying
the non-linear relative effectiveness enhancement (sometimes labeled synergism) in laboratory
Halon Replacements: Shortly thereafter however, CF2BrH was removed from consideration as a halon replacement
Shortly thereafter however, CF2BrH was removed from consideration as a halon replacement by
a new criterion for ODP; less than 0.05. Throughout the search for halon replacements, the
moving target requirements, frequently not well defined, have presented ever more stringent
restrictions. ICI in the UK felt toxicity was too much a concern for CF2BrH to be a viable
solution. Further, they felt it unlikely any feasible chemically active fire suppressant would be
able to pass both environmental and toxicity bars. They left this market sector. The uncertainty
of moving ODP targets is not conducive to industry investment. This was especially so as CFC
replacement was an easier challenge and a much larger potential market.
The fire protection community, suppliers and users, have responded admirably in working to
assure fire protection while helping to also decrease the threat to the environment. Concerted
efforts have been made for responsible use of halons. In addition to exploring alternative ways
for providing protection, advances were made in minimizing leaks, inadvertent system
discharges, testing and training. At the first “International Conference on CFC and Halon
Alternatives” in 1989, I was able to state that the US Navy was able to reduce
halon discharges to the atmosphere by almost 75 percent.
The “Second Conference on the fire protecting Halons and the environment” in Geneva in 1990
saw a greatly increased appreciation of the halon community issues. A variety of approaches,
including videos of pyrotechnic devices from Russian efforts, were covered.
Halon alternative efforts got a real boost in 1991 with the advent of the “Halon Alternatives
Technical Working Conference” held in Albuquerque, New Mexico. Bob Tapscott of NMERI
served us very well in shepherding these annual conferences, called the “Halon Options
Technical Working Conference” or HOTWC since 1994. This conference, with the help of
Doug Mather at the University of New Mexico and the organizational support of the Next
Generation Program under Dick Gann, continues to be a technology exchange mainstay for
scientists, engineers, vendors and users on the many aspects of halon substitutes.
Halon Replacements: The technical community responses to address the environmental drivers
The technical community responses to address the environmental drivers have included
searching for halon-like replacements and understanding halon combustion suppression. Other
searches have been more broadly based on replacing the fire protection capabilities halon
supplied. A serious consideration of risk analysis frequently suggested alternatives
implementable without new halon replacements. In all cases, identifying a “solution” demands
the frequently more difficult task of enabling proper implementation. Science without enabling
technology does not address our needs. The 1995 ACS symposium “Halon Replacements:
Technology and Science” explored many aspects from fundamental science through applications.
As with the predecessor ACS symposium in 1975, the proceedings papers are published as ACS
Symposium Series #611. A review of NRL efforts is included in the publication.
Many of the difficult to solve problems relate to protecting fuel loaded movable military
platforms. The DoD can proudly claim very significant efforts with solutions applicable to many
civilian applications. Many lead actions and breakthroughs came from military sponsored
efforts. Our NRL efforts on clean agent halon replacements led to the selection of a hydrofluorocarbon
as the best available solution for several specific navy ship fire threat scenarios. We have
provided detailed design guidance for systems employing HFC-227ea which is being
implemented aboard the LPD-17 and CVN-76, new ships that are being constructed without
ODS materials aboard. However, such gaseous agent systems (including halon 1301) do not
provide cooling. Also, HFC agent – fire interactions produce far more HF (5-8 times) than was
produced with halon 1301. In response, we invented a hybrid gaseous agent – water spray
cooling system (WSCS) (United States Patent 5,918,680, July 6, 1999) to provide cooling,
minimize agent by-products, minimize reflash potential, and facilitate post-casualty compartment
Several Army representatives were present aboard the ex-USS SHADWELL, NRL’s Advanced
Fire Research Vessel, during full-scale development testing. They were sufficiently impressed to
advocate incorporating the WSCS technology in Army watercraft. Budgets can contain different
types of funding and programs may not communicate adequately to allow approaching optimum
results. The Army had very significant funding available for a limited time period for
implementation but no funding for development. To date, the Army has replaced halon 1301
total flooding systems aboard 60 watercraft machinery spaces (up to 1700 m3) with the NRL
patented system and our general guidance. They were not able to devote efforts to optimize the
specific operational parameters. This is definitely a halon replacement success story, but as
sometimes happens in a non-ideal world, a qualified success that could be improved upon.
Halon Replacements: A key point to emphasize is that satisfactory solutions are not always
A key point to emphasize is that satisfactory solutions are not always capable of being optimized
due to non-technical considerations. Knowing what agent can serve as a halon substitute is not
the same as knowing how to properly implement an operational system, let alone taking full
advantage of that capability.
Perceptions play important roles. A scientific fact is subject to evaluation and must be
independently verified. A legal fact is one established in a court of law by virtue of being
accepted by a Judge and jury. A fact in the public arena is a viewpoint accepted by the people.
Differences in viewpoints exist with different countries having different tolerances to HCFCs,
PFCs, global warming gases, and various atmospheric lifetimes. Realities within different
countries can also be different. Different countries thus evolve different production and usage
phase-out schedules for different compound classes. Commerce, airline, ship and military
equipment movement gets complicated in this era of global interactions.
I have been privileged to serve as a US Government Representative and Consulting Expert on
the Halons Technical Options Committee (HTOC), which advises the participating governments
of the world on the Montreal Protocol Treaty via the United Nations Environment Program
(UNEP). The experience continually reinforces the importance of the large number of factors in
addition to science involved in efforts to minimize mankind caused ozone layer depletion. It is
amazing how a disparate group of people with very different interests and agendas can so
constructively form a productive consensus output. This has been in significant measure a
tribute to the efforts of the members, especially the early co-chairs Gary Taylor and Walter
Exposure to different situations at HTOC meetings showed me that someone else might consider
a use of halon viewed by many as not important to be crucial. Being able to use automobiles
well into the car’s old age is important in Mexico. Being able to extinguish a car engine fire with
halon 1211 allows the engine and most residual wiring to be repaired without high cost.
Alternative suppressants may not allow home repairs or cause significant economic impact.
Halon Replacements: A personal computer might be regarded as expendable...
A personal computer might be regarded as expendable in some countries, but when the only PC
in the town is used to run a factory, protection is vital. Water sprinklers may be perfectly
adequate to deal with a fire threat, but if half the time when one turns on the water spigot and
nothing comes out, sprinklers are not a viable halon alternative.
High technology countries can also have their particular needs. High-rise concrete garages in
Japan cannot easily be converted to water based systems because drainage was not built in. A
halon system may be only one of many viable fire protection modes, but once a facility is built
around its characteristics, converting to a different system can be exceedingly difficult.
Facilities with political or national prestige may also be thought to necessitate halon.
In practice, the different sovereign states determine for themselves what is truly important for
their requirements. With the advent of production phase-out, signatories must follow a
procedure to request production exemptions if existing halon supplies are not available to meet
needs. The HTOC is the initial evaluation point for granting production exemptions under the
Montreal Protocol. I remember when the first set of approximately 20 requests for exemptions
was to be dealt with. A high placed gentleman in the UNEP administration was seated next to
me. He noted that sovereign nations had submitted formal requests. It would be an
embarrassment if they were turned down. I politely informed him that I did not feel this was the
basis for the operation of a technical committee. In the end, we did not cause any one country
embarrassment. We turned down all requests based on our knowledge of halon availability.
They simply did not need any new production to satisfy their needs.
Halon Replacements: Availability of existing supplies of halons 1301 and 1211...
Availability of existing supplies of halons 1301 and 1211 served to buffer transition to
alternatives and maintain supply for remaining legacy essential uses. Russia was unique as there
was no reserve of halon 2402 available in international commerce to smooth the phase-out
transition. Russia was later allowed a measured decreasing production allowance by the UNEP.
India as a large developing country (Article V country under the Montreal Protocol) has
progressed very far in elimination of halon dependence. Much credit is due to Mr. H. S.
Kaprwan of the Indian Defence Institute of Fire Research for facilitating the effort.
China as a developing country also has an extended time period for phasing out production of
halons. Their continued allowed production peaked several years ago at approximately 14,000
tons/year. Most of this production was of halon 1211 for portable extinguishers. While ozone
depleting substance production worldwide had been decreasing, halon concentrations in the
atmosphere were increasing. This may be due in part to the Chinese production. Also usage in
limited lifetime handheld units would lead to future releases. The UN Multilateral Fund
arranged for a halon and CFC production reduction program in advance of mandatory
scheduling, including contributory payments of approximately $100 million. While the cost is
large, it is a very efficient use of funds for the impact achieved. The success is due in no small
part to the limited number of officials who were involved. A similar attempt in a less controlled
economy with strong private interest groups present would have been much more difficult.
The program for phasing out halons in China had a very dramatic success in Shanghai. Use
control on halon extinguishers resulted in a very significant decrease in market demand. Local
authorities then banned production and sale of halon extinguishers, as well as forbidding all
halon 1211 agent and extinguishers from entering Shanghai, effective January 1, 2000. While
there were possibilities of using this forward momentum for speeding up the phase-out of halons
in the rest of China, program structure and bureaucratic realities provided too much status quo
inertia. The World Bank-China ten-year plan had been approved with various international
entities involved. Modifying the agreements for a shorter time frame could have been difficult.
The current plan does not have provision for advancing payment of support funds, nor can the
implementation payments continue to be made once the phase-out is completed.
Halon Replacements: Economic and political programs can develop lives of their
Economic and political programs can develop lives of their own, not directly dependent on
scientific or technical capabilities. This is a reality of the non-technical complexity of halon
Political imperatives are an important aspect of issues with commercial impact; halon
replacement is no exception. One country proposed a modification to the Montreal Protocol to
help achieve a faster phase-out. Three other countries cosponsored the action that appeared to be
good environmental activism. The impact in the opinion of many HTOC members would have
been premature destruction of halon before more accurate knowledge of the amount of existing
stock for legacy essential systems was gathered. The proposal was not supported by HTOC and
was later not supported by the policy makers. A side issue was that the proposing country
contained a manufacturer that thought it had a near drop-in halon replacement. More rapid halon
withdrawal would have meant business.
The focus of HTOC has changed repeatedly with the maturation of halon replacement efforts.
HTOC exists to serve as a technical advisory body. With halon production halted in developed
countries, some parties to the protocol prefer to initiate halon destruction. Questions are posed
for reply. Sometimes parties prefer actions that may not be supportable by data available at the
time. The HTOC has to be able to educate and convince others as to why such positions may not
be optimum. It can be difficult to provide a convincing technical reply when a different
conclusion has been reached based on other considerations. Such an interaction on a policy level
is not the domain of scientific research to find halon replacements, but it is an important part of
the dynamics of evolving environmental laws governing our actions. This is a true adventure for
this former basic science researcher.
Were the sky parchment,
Were all reeds quills,
Were the seas and all waters ink,
Were all the world’s inhabitants scribes,
It would not suffice to record the intricacies of government.
Significant future events include the European Union legislation banning refilling of halon
systems after 31 December 2002, and the required decommissioning of all systems by 31
December 2003. There will be exemptions for certain essential uses.
Halon Replacements: The cost of recycled halon is already greatly reduced...
The cost of recycled halon is already greatly reduced with the decommissioned halon becoming
available on the market. Care must always be exercised in designing a decommissioning
program. If an owner’s concern about being responsible for possessing an environmentally
hazardous material overcomes the perceived value of the material as an asset, we may find
accidental discharges and fires increasing. This is opposite to the conscientious treatment seen
so far, but always a consideration.
Another significant future event will occur in 2010 when the Montreal Protocol Article 5
countries, the developing countries, must cease halon production. Many countries have acted
very well. Many others can only address their needs with continued financial and technical aid.
The continuation of the multilateral fund is crucial.
Obtaining real-world economically and technically feasible solutions, while looking over your
shoulder as ground rules modifications gain on your efforts, has supplied us a thrilling and very
challenging ride. We can be proud of many successes. The quest continues for addressing the
remaining difficult challenges.
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