Revisiting fire safety fundamentals when flammable refrigerants enter everyday applications.

Recently, I was asked to do a short review of fire risks in refrigeration systems—and you might be surprised to learn that the flammability of refrigerants really didn’t feature much in my analysis.

The specific question was whether fire risks were greater in wintertime and, if so, what could be done about that. I identified several reasons why I believe that a greater risk of fire exists in winter.

Sometimes people think that a fire is less likely to start in cold weather or inside a refrigerated space, but in fact, the moisture level in the air is bound to be lower under these conditions so fires can start more easily. It is also more likely that some form of auxiliary heating is being used, which greatly increases the probability of ignition of combustible material. Possible combustion sources include blow torches, diesel or gas generators, electric task lighting, electric heaters, gas-fired heaters and other temporary heat sources. All of these devices are more likely to be necessary and used indoors during winter.

Fire can also be started by faulty electrical equipment in several ways. If the power cables for field connections of equipment are undersized they may overheat and cause the cable insulation to ignite. If a termination of a power cable is loose it will tend to create a higher resistance to current flow and will act as an electric heater, possibly causing a fire in the terminal box. If equipment is damaged or faulty it can cause a spark to earth, for example from the terminals of a heater rod, which can cause combustible material to be ignited.

Often the product being chilled, frozen or stored is highly combustible. In a 2008 cold store fire in New Zealand, which killed one firefighter and injured several others, the product was butter. Once the building was alight, it burned vigorously for days as the product fueled the fire. In a bakery the food product is combustible, but fine powders such as flour or starch are also highly flammable and particularly hazardous. It is extremely important to ensure that combustible material does not accumulate in areas where it could be set aflame. This includes food waste and packaging material in factories, but also waste oil, scraps of wood, insulation, cloth, rags or paper and any other waste material. Plant rooms must not be used for storage of any kind. Good housekeeping is an essential part of fire prevention.

Hot work poses a particular danger. This includes welding, brazing and flame cutting, but also covers grinding, cutting and any other process that generates sparks or uses a naked flame. This is particularly dangerous in a dusty environment or where there is additional combustible material, including wooden floors. Any process that includes the possibility of hot work requires particular precautions to be taken before, during and after the work process. A permit to work is essential for all hot work, and particular care must be taken to conform to all insurance requirements including provision of emergency equipment and fire-watching requirements after the work has been completed.

The most common causes of fires in cold stores, food factories and offices are electrical faults caused by faulty equipment, loose connections, frayed cables, short circuits and undersized wiring. Poorly supervised use of flames and sparks, such as blow torches or grinders, are also a common cause of fires. Malicious damage like arson is also a possible cause, which makes it more important to ensure that flammable material is tidied away and properly discarded.

Try to ensure that your contact with blazing fires is always a positive experience.

KLAUS MUELLER, CC BY-SA 2.0 DE VIA WIKIMEDIA COMMONS