TIME QUICKLY RUNNING OUT ON HALON:
WILL A SUBSTITUTE BE FOUND?
By Robert Merritt
The pressure on Corporate America to find effective alternatives to halons recently intensified as the Montreal Protocol (the
international agreement to reduce ozone-depleting chemicals) was again revised. The agreement now calls for a phaseout of the
production of halons, very effective fire suppressants with extremely severe ozone-depleting properties, by January 1, 1994.
This decisions implications are far-reaching, as Halon 1301 and Halon 1211 are widely used as fire suppressants in control rooms, telephone central offices, computer rooms, museums and aircraft.
Halons have become the fire suppressants of choice in such facilities because they evaporate quickly, leave no residue, and are nontoxic, noncorrosive, and electrically nonconductive.
A substitute must match halons impressive fire-fighting capabilities and cost-effectiveness, while achieving an ozone depletion potential (ODP) lower than 0.2, the level that must be met under the terms of the Montreal Protocol and the Clean Air Act of 1990 (Halon 1301 has an ODP at least 50 times greater than that).
This substitute, like Halon 1301 which is used in stationary fire protection systems, should be acceptable for use in occupied areas at recommended extinguishing concentrations and compatible with electronic equipment.
Thus far, manufacturers have identified several possible alternatives to halons. However, the U.S. Environmental Protection Agency (EPA) has yet to issue a list of acceptable alternatives under its Significant New Alternatives Policy Program (SNAP). Until such a list is issued or the proposed alternatives are otherwise recognized by the EPA, no products can be marketed as halon alternatives.
Right now, there is a great deal of interest in one possible halon alternative known as Inergen, a mixture of nitrogen, argon and carbon dioxide that has no adverse environmental impact.
However, Inergen is an oxygen depleting gas. Carbon dioxide is included in the compound to create a respirable atmosphere, a physiologic concept still being evaluated, but expected to mitigate the dangers of having personnel exposed to a reduced-oxygen atmosphere.
Other widely discussed alternatives are hydrofluorocarbons (HFCs) or fluorocarbons.
However, one potential problem with these proposed alternatives is that they can break down into hydrogen fluoride, which is highly corrosive and toxic.
Hydrochlorofluorocarbons (HCFCs) have also been mentioned as alternatives, but also are covered in the Montreal Protocol. They are scheduled to be phased out of production starting in 1996.
It is expected that many of these concerns over halon substitutes will be resolved, or at least clarified, with issuance of the EPAs SNAP lists. However, in the meantime, Factory Mutual Research and Engineering (FME&R) recommends:
Companies should no longer install new halon fire protection equipment in consideration of the environmental issue and the anticipated shortage of replacement agent and the need to reserve it, where available, for essential use.
Facilities with existing halon systems keep them in service at least for near term until suitable replacements become available unless they can reduce risk to an acceptable level without such protection. (Note that local legislation might require the immediate removal of such systems, as is reportedly the case in Germany.)
Facilities subdivide critical equipment into the smallest areas possible, thus reducing exposure to fire and damage from fire suppressants.
Robert Merritt is a Project Engineer at Factory Mutual Research Corporation (FMRC) in Norwood, Massachusetts.
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