Air conditioners are not as flammable as some gases, such as propane, but they can still ignite and burn under the right conditions. To ensure your air conditioner is working properly and to reduce the risk of fire, it is essential to schedule regular professional maintenance inspections in the fall and spring. Additionally, it is important to keep the area around the outdoor condenser unit clean and free of debris, leaving at least two to three feet of space on all sides. This will give the condenser enough “room to breathe”.The use of refrigerants in refrigeration and air conditioning equipment can come with a variety of risks, including toxicity, flammability, suffocation, and physical hazards.
In 1930, Dr. Thomas Midgley and his partners Albert Leon Henne and Robert Reed McNary observed that the refrigerants used at the time were made up of a few chemical elements that were grouped together on the periodic table of elements. The element at the intersection was fluorine, which is toxic in its own right. However, Midgley and his team believed that fluorine-containing compounds could be non-toxic or flammable.To simplify the identification of organic fluorides for a systematic search, an abbreviated convention was introduced.
This convention is still used today as a numbering system for refrigerants. The numerical designation of each coolant indicates both its chemical composition and structure. After three days of research, Midgley and his team had identified and synthesized a chlorofluorocarbon (CFC), dichlorodifluoromethane (R-1). Surprisingly, when tested on an animal, it had no effect.
However, when tested with another sample, the guinea pig died. Further examination of antimony trifluoride showed that four out of five bottles contained water. This contaminant forms phosgene (CoCl) when antimony trifluoride reacts with carbon tetrachloride. If one of these contaminated samples had been used in the initial test, it could have delayed the discovery of organic fluorine-containing refrigerants for years. It wasn't until almost half a century later that CFCs were recognized for their damage to the environment when released into the atmosphere. This includes depletion of stratospheric ozone and global warming as greenhouse gases.
The high stability of CFCs allows them to deliver ozone-depleting chlorine to the stratosphere. This same stability extends their life in the atmosphere and makes them persistent as greenhouse gases. An ideal refrigerant would be non-toxic, non-flammable, completely stable within a system, environmentally benign even with respect to decay products, self-lubricating or compatible with lubricants, compatible with other materials used to manufacture and maintain cooling systems, easy to handle and detect, and inexpensive. It would also not require extreme pressures. The chances of developing an “ideal” coolant are slim; however, manufacturers strive to meet as many ideal properties as possible. According to Paracelsus' 16th century principle of toxicology - “the dose solo facit venenum” - all substances can be toxic in sufficient quantities.
Toxic effects have been observed in substances as common as water, table salt, oxygen and carbon dioxide in extreme amounts. The difference between those considered safe and those considered toxic is the amount or concentration needed to cause harm and sometimes the duration or repetition of exposures. Substances that present a high risk in small amounts even with brief exposures are considered highly toxic. Those for whom practical exposures do not cause any harm are considered safer. Due to negative marketing by competing equipment and refrigerant suppliers, concerns about the safety of refrigerants have increased. Exaggerations (to influence customer perceptions) along with contradictions have caused discomfort when choosing alternative refrigerants. Acute toxicity refers to the impacts of single (or short-term) exposures often at high concentrations.
It suggests the possible levels of risk from accidental releases such as those caused by spills or system breakdowns. Acute toxicity also serves to measure service operations where high exposures may be experienced for short periods. Chronic toxicity refers to the effects of repeated or sustained exposures over an extended period such as those experienced throughout life working in machine rooms. In reality few technicians spend all day in engine rooms and concentrations can fluctuate; therefore most chronic exposure rates are expressed as time-weighted average values (TWA). It is important to mitigate and reduce acute risks associated with refrigerants.
