|
Feature
Article
During the past 30 years, the use
of the clean fire suppression agent Halon 1211 in streaming
applications has prevented the loss of human life, and Halon 1211
systems currently protect billions of dollars worth of equipment
worldwide. However, because of its implication in the destruction of
stratospheric ozone, the production of Halon 1211 was banned in
developed countries commencing on January 1, 1994. As a result,
intensive research efforts have been undertaken in the industrial,
academic, and governmental sectors with the goal of developing
substitutes for this valuable suppression agent.
The ideal Halon 1211 substitute, in
addition to possessing the desirable characteristics of Halon 1211
itself, is required to have a much lessened environmental impact
with regard to its potential for ozone depletion, and also with
regard to its potential for contributing to global warming. Hence,
one possible set of requirements for the ideal Halon 1211 substitute
is as follows:
1. Highly efficient fire
suppression
2. Clean extinguishment (no residue)
3. Zero ozone
deletion potential (ODP)
4. Nonconducting
5. Storage
stable
6. Non-toxic
7. Zero global warming potential
(GWP)
8. Manufacturable at reasonable cost
To date no substitute has been found
which satisfies all of the above requirements, although substitutes
have been found which satisfy some of the above criteria.
SUBSTITUTES FOR HALON
1211
Table 1 lists those substitutes
currently approved for use as streaming agents under the U.S. EPA
Significant New Alternatives Policy (SNAP). Table 2 shows those
substitutes approved for use as streaming agents under SNAP which
are subject to narrowed use limits. Substitutes subject to narrowed
use limits are acceptable for use only in certain applications, for
example, in applications where other alternatives are not
technically feasible due to performance or safety requirements. For
details on the narrowed use limits for individual substitutes listed
in Table 2, see the U.S. EPA website (http://www.epa.gov/ozone/snap/fire/lists/stream.html).
Table 1. Agents Acceptable
Under SNAP as Substitutes for
Halon 1211 in Streaming
Applications
| Substitute |
Tradename |
Manufacturer |
Chemical Formula |
Approved for Residential Use? |
Contact Information |
| HCFC-123 |
FE-232 |
DuPont |
CF3CHCl2 |
NO |
http://www.dupont.com/ |
| HCFC-124 |
FE-241 |
DuPont |
CF3CHFCl |
NO |
www.dupont.com/fire |
| HCFC Blend B |
Halotron I |
American Pacific Corp. |
3 component blend based on HCFC-123 |
NO |
http://www.halotron-inc.com/ |
| HCFC Blend C |
NAF P-III |
NAF Int'l/ Safety Hi-Tech |
55% HCFC-123, 31% HFC-124, 10% HFC-134a, 4% D-limonene |
NO |
http://www.safetyhitech.com/ |
| HCFC Blend D |
Blitz III |
NAF Int'l/Safety Hi-Tech |
HCFC-123 plus proprietary additive |
NO |
http://www.safetyhitech.com/ |
| Gelled Halocarbon/ Dry Chemical Suspension |
Envirogel |
Powsus |
Halocarbon plus dry chemical plus gelling agent |
YES |
http://www.powsus.com/ |
| Surfactant Blend A |
Cold Fire |
Firefreeze Worldwide, Inc. |
Mixture of organic surfactants and water |
YES |
http://www.firefreeze.com/ |
| Carbon dioxide |
- |
- |
CO2 |
YES |
- |
| Water |
- |
- |
H2O |
YES |
- |
Under current SNAP guidelines,
hydrochlorofluorocarbons (HCFCs) cannot be employed in residential
extinguishers, but are allowed in commercial, watercraft and
aircraft use in portables.
Due to their non-zero ODP, HCFCs are
currently scheduled for a production phase-out by 2030.
Under SNAP guidelines,
perfluorocarbons (PFCs) are acceptable for nonresidential use only
when other alternatives are not technically feasible.
It should be noted that not all of the
agents listed in Tables 1 and 2 are clean agents. For example,
water, foam, dry chemical and the gelled halocarbon/dry chemical
suspension will leave a residue following extinguishment which must
be cleaned up.
Two of the more popular Halon 1211
substitutes are Halotron® I and FE-36TM. These agents are suitable
for typical streaming applications, including the protection of
high-value assets such as computer rooms, process control rooms,
laboratories and aircraft. Halotron® I, produced by American Pacific
Corporation, is an HCFC-123 (CF3CHCl2) based mixture containing
minor quantities of argon and carbon tetrafluoride (CF4). Halotron®
I has been approved by the U.S.
Table 2. Agents Acceptable Under
SNAP as Substitutes for
Halon 1211 in Streaming Applications
Subject to Narrowed Use Limits
Federal Aviation Administration (FAA)
for airport fire fighting (on flight lines and at gates) and more
than 50 U.S. airports employ 460-500 pound Halotron® I systems on
their aircraft rescue and fire-fighting (ARFF) vehicles. Halotron I
has been approved by the U.S. FAA for on-board use in a UL listed
portable, and United States Coast Guard (USCG) approved portable
units are available. Halotron® I units are available with UL ratings
ranging from UL 1B:C portable units up to UL 10A 80B:C wheeled
units.
FE-36TM, produced by
DuPont, is the hydrofluorocarbon HFC-236fa (CF3CH2CF3).
FE-36TM is a zero ODP replacement for Halon 1211 and has
been approved by the U.S. FAA for on-board use in a UL listed
portable. FE-36TM has also been approved for use auto
racing applications. In the U.S., FE-36TM portable units
are available with UL ratings ranging from UL 2B:C to UL 2A 10B:C.
All UL listed FE-36TM portables are United States Coast
Guard (USCG) approved. In Europe, EN3 listed units are available
with 34B, 5A:55B and 8A:70B ratings.
Table 3 compares the extinguishing
efficiencies of Halon 1211, Halotron® I and FE-36TM, and
Table 4 compares the environmental and toxicological characteristics
of the three agents. In Table 4 the NOAEL (no observed adverse
effect level) is the highest concentration at which no adverse
toxicological or physiological effect has been observed; the LOAEL
(lowest observed adverse effect level) is the lowest concentration
at which an adverse toxicological or physiological effect has been
observed.
Table 3. Fire Suppression
Efficiency: Halon 1211, Halotron® I and
FE-36TM
| UL Rating |
Kilograms of Agent Required for UL
Rating |
| Halon 1211 |
Halotron I |
FE-36 |
| 2B:C |
0.6 |
1.1 |
1.1 |
| 5B:C |
1.1 |
2.3 |
2.2 |
| 1A 10B:C |
4.1 |
5 |
4.3 |
| 2A 10B:C |
- |
7 |
6 |
| 2A 40B:C |
5.9 |
- |
- |
| 4A 60B:C |
. |
29.5 |
- |
| 4A 80B:C |
7.7 |
. |
. |
| 10A 80B:C |
- |
68 |
- |
| 30A 240B:C |
68 |
- |
- |
Table 4. Comparison of
Toxicological and Environmental Properties
| Property |
Halon 1211 |
Halotron® I |
FE-36TM |
| ODP |
3 |
0.014a |
0 |
| GWP (100 year integrated time horizon) |
1300 |
CF3CHCl2 = 120
CF4 = 5700
Ar = 0 |
9400 |
| Atmospheric Lifetime, years |
11 |
CF3CHCl2 = 1.4
CF4 = 50,000
Ar = 0 |
220 |
| NOAEL |
0.5 |
1 |
10 |
| LOAEL |
1 |
2 |
15 |
RECENT ADDITIONS
The two most recent additions to the
list of SNAP approved streaming agents are the H-Galden
hydrofluoropolyethers (HFPEs), produced by Solvay Solexis, and the
perfluorinated ketone agent NovecTM 1230, produced by 3M
Corporation. The H-Galden HFPEs are low molecular weight linear
fluorinated polyethers capped on both ends with hydrogen, and are
characterized by zero ODP and low GWP.
NovecTM 1230 is the fluorinated ketone
1,1,1,2,2,4,5,5,5-Nonafluoro-4-(trifluoromethyl)-3-pentanone,
marketed by 3M. NovecTM 1230 is rapidly decomposed by interaction
with the ultraviolet radiation from the sun, and as a result, the
atmospheric lifetime and GWP of the agent are low. 3M has reported
an atmospheric lifetime of approximately five days, and a GWP of 1.
NovecTM 1230 contains no bromine or chlorine, and hence it has an
ozone depletion potential (ODP) of zero.
CONCLUSION
In response to the production ban on
Halon 1211, numerous Halon 1211 substitutes have been developed and
commercialized. With the advent of these new agents, businesses
worldwide will continue to have the ability to protect critical
equipment and irreplaceable items, despite the ban and inevitable
disappearance of Halon 1211 from the marketplace.
IFP | 