By James Burns
Most of us can recall environmental issues affecting fire safety in the past. Consider the move to raise all underground tanks above ground. In their effort to solve an environmental problem, the initial effort didn’t recognize that (unprotected) above ground tanks killed many firefighters over the years (thus the reason they were usually placed below ground, especially in urban environments.) The fire service responded, working with Underwriters Laboratories (UL) to create a standard for protected above ground tanks that is currently the ultimate in safety for above ground tanks. When halon became an environmental pariah, industry developed alternatives that satisfied the need for clean agent extinguishing systems and portables. Each of these examples are clear cases where fire service and industry worked hand in hand to develop alternatives that satisfy the environmental concerns without jeopardizing the safety of the public and firefighters.
Now we’re facing an industry that has responded to an environmental concern by creating a significant fire risk to our communities. I’m talking about refrigerants – that stuff in your air conditioning system that makes it cool. Historically, the refrigerants in our homes and businesses have been non-flammable and non-toxic. Unfortunately, the current refrigerants have a chemical in them that adds considerably to global warming; the term used in environmental circles is “high gwp” (global warming potential) materials. The refrigeration industry was put on notice that changes must be made, and they responded by creating new refrigerants that had lower gwp numbers, but also had a flammability characteristic. Many of these products have low flame velocity, are difficult to ignite, and are safer than high flammability gases like propane. That said, they still burn, and in tests conducted by the industry at the UL facility in Northbrook, Illinois, it was discovered that, under ideal circumstances, they will ignite and burn with a very high intensity. In addition to the fire risk, a combustion byproduct of this material is hydrogen fluoride, which is a toxic, corrosive material that can maim or kill through inhalation, contact, or ingestion. These risks must be considered if we’re to accept these new refrigerants in our communities.
Historically, we’ve depended upon codes and standards to address the risks of new trends in construction, and this should be no different. Currently, the codes and standard that are being modified to accommodate the use of these materials are not so much the fire and building codes but the standards relating to air conditioning equipment. Unfortunately, because these products haven’t been an issue in the past, fire service representation has thus far been almost nonexistent in the development of risk mitigation in the standards. There is, however, a standard currently under development that has the potential to appropriately address the issues – a UL standard, UL 60335-2-40. Unfortunately, the committee that has been working on drafting the requirements is without the expertise of fire service members, and by all appearances, is without risk management members with a knowledge of flammability risks. That has resulted in a series of proposed solutions that are, at best, lacking.
One of the primary means to control the consequences of hazardous materials is to keep the quantity of a material to a manageable amount; when that amount is exceeded, then additional controls are used to dilute, contain, or otherwise address the hazard. However, in the standard currently being developed, the amount of flammable gas allowed in a refrigeration system is based upon the size of the room. That means if the room is large enough, a significant quantity of flammable gas can be used with no additional safety measures. I should point out that in our building and fire codes, all hazardous materials have a clear exempt amount that is independent of the room size. This philosophy of letting the room size determine the amount of flammable gas allowed in a system assumes that any release will immediately be mixed with the air in the room, which simply isn’t the case. If there are large-charge sizes allowed without additional safety measures, the risk is unacceptable.
Another issue is that the risk mitigation scheme for these installations depends upon detection of the leaking refrigerant. This might be appropriate, but now, the detection technology isn’t adequate for this application. Current refrigerant detectors migrate out of calibration in a short period of time, rendering them inoperable or in a constant state of alarm. For equipment that is in service for decades, this isn’t adequate.
There are many other issues related to the standards and other model regulations aimed at making these installations safe, however there isn’t enough space here to review them all.
Please consider contacting the UL Project Manager Alan McGrath ([email protected]) on this subject matter to request that they refrain from publishing this standard until the public safety community is included in the discussion, so that we can be confidently tell our communities that the new refrigerants can be used safely.
James Burns is the retired New York State Fire Administrator.