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| Shapiro, Washburn & Sharp

Every year ammonia refrigeration systems cause accidents and explosions in large commercial factories across the United States. Although large companies are aware of the risks of using ammonia refrigeration, it is very important that companies inform their workers of these risks as well. Workers who may be exposed to ammonia or become victims of an ammonia blast should know the potentially lethal effects of this chemical. Even a small leak in these refrigeration systems can have deadly consequences if not caught in time. Ammonia refrigeration is very dangerous because when the chemical is mixed with air in the 16%-25% range it can cause a large explosion capable of leveling an entire building. The ammonia itself is also very toxic and is corrosive to the eyes, skin, and lungs. Workers involved in ammonia accidents of this type are likely to sustain severe injuries and burns if they survive. Even though ammonia is a serious health hazard, many large corporations choose to use this type of refrigeration because of ammonia’s heat transferring properties, its cost effectiveness, its wide availability, and its low impact on the environment.


As OSHA and EPA regulations for ammonia refrigeration systems are becoming more stringent, corporations and insurance companies are looking for an alternative to ammonia refrigeration that would also minimize the safety risk to workers. It seems that carbon dioxide may be a good candidate for future refrigeration systems. Carbon dioxide refrigeration is already being widely used in Europe because unlike ammonia, carbon dioxide does not pose a health risk and is non-toxic and non-flammable. Since carbon dioxide is a benign chemical it is also not heavily regulated by OSHA or the EPA. Carbon dioxide does have some drawbacks however. Carbon dioxide is very effective for use in freezers, and coolers in the low range of the temperature scale, but is not very effective for the high side of the scale for use in an engine room or condensers because carbon dioxide has to be highly pressurized.


However, many companies have found that using both ammonia and carbon dioxide is a very effective method. Using both chemicals allows for effective use with low and high scales. It also increases safety because concentrations of ammonia will be lower and the ammonia will be contained in areas such as engine rooms far away from workers. This method using both ammonia and carbon dioxide is called a CO2/Ammonia Cascade System and it is likely to replace refrigeration systems that use ammonia alone in the next few years. Greenhouse gases called chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) that have been commonly used as refrigerants are being banned and phased out in most developed countries including the United States. These bans have led companies to seek alternative refrigerants that do not have a negative impact on the environment. As the United States is scheduled to conclude its phase out of HCFCs by 2030, refrigerants such as ammonia and carbon dioxide that are non-ozone depleting will be more widely used. The CO2/Ammonia Cascade System that offers the advantage of increased safety may very well be the future of refrigeration.


About the Editors: Shapiro, Cooper, Lewis & Appleton personal injury law firm (VA-NC law offices ) edits the injury law blogs Virginia Beach Injuryboard, Norfolk Injuryboard, as well as the Northeast North Carolina Injuryboard as a pro bono service to consumers. Lawyers licensed in: VA, NC, SC, WV, DC, KY, who handle car, truck, railroad, and medical negligence cases and more.


  1. Gravatar for Max Lindsay
    Max Lindsay

    Dear Sirs/Ma'ams,

    I have to correct something you identified in your posting/blog (Will Dangerous Ammonia Refrigeration Systems be Phased Out?) and also provide you some more potential clients...

    CO2 System refrigeration systems can be just as deadly or more deadly than ammonia systems. CO2 is heavier than air and can easily kill MANY persons during a release ... and they won't even know it's happening (to some extent, your suggestion creates a liability to your organization by leading people to believe that CO2 is less dangerous than ammonia). The human body is programmed to respond to the presence of ammonia in concentrations WELL below the IDLH for ammonia. With CO2, you just fall asleep and the lights to out.

    You may want to be more careful in your postings and also write a similar page discussing the dangers of CO2 refrigeration as well as Freon and Freon derivatives (also heavier than air).

    Best regards,

    G. J. "Max" Lindsay

    Ammonia Process Safety Engineer

  2. Gravatar for Shapiro, Lewis & Appleton
    Shapiro, Lewis & Appleton

    Dear Max:

    Thank you for your thoughts. It sounds like you are an industry insider who likely knows more of these dangers than I do as a lawyer. I did not intend to advocate for one system or the other, but to point out some dangers I read about for workers’ safety. My main thought is that the industry needs to use care to keep folks safe when using such powerful and volatile substances.

    Best regards,

    John M. Cooper

  3. Gravatar for TJ


    In the age of the Internet, posts like this garner more attention than in the past. I found this blog post from an automatic search on ammonia from Google. With increased visibility comes increased responsibility. As the previous poster pointed out, Mr. Cooper's post does not demonstrate proper concern for the technical details regarding refrigeration alternatives.

    For those that have found this post, please understand that THERE IS NO INHERENTLY SAFE REFRIGERANT! Give the size & complexity of today's industrial refrigeration systems, every substance used for refrigeration has dangers. Max correctly points out one for CO2, HCFCs (like R22), & HFCs (like R134a, R404a): asphyxiation with no warning. Regardless of the refrigerant choice, there are risks, especially for those that are tasked with operating & maintaining the systems.

    Risks MUST be managed, and frankly, moving away from ammonia will only increase the likelihood that risks will NOT be managed & those same workers will be left with MORE risk. Everyone knows that ammonia is hazardous, think how we will treat a refrigerant that is considered "safe"?

    Mr. Cooper, you say in your response that are simply pointing out some dangers with regard to workers' safety. I agree, workers' safety is critical; however, the refrigerant is not the issue. Advocating proper training of personnel & proper maintenance procedures for the system regardless of refrigerant would be a better target.

    Ammonia has been around for over 150 years as the refrigerant of choice for industrial applications. It has also logged more person-hour of interaction (i.e. maintenance) than probably any other chemical today (especially when you add up the refrigeration & fertilizer industries). Many plants prove every year that ammonia can be safely & effectively used as an industrial refrigerant, yet every year workers are injured. A closer look at the details of this incident (and others) will probably show that the situation could have been avoided with proper management.

    Respectfully submitted.

  4. Gravatar for Mike Fisher
    Mike Fisher

    Dear Mr. Cooper,

    I must admit my first reaction to the title was one of frustration.

    As other previous posters have mentioned it is advisable to treat any refrigerant as potentially dangerous. Many other refrigerants pose significant dangers from oxygen deprivation, chemical changes into potentially more dangerous compounds, or yes, potentially flammable mixtures also.

    It is important to read the MSDS for the specific chemical compound!

    Anhydrous ammonia (NH3) is often called "The self alarming refrigerant" for a reason. The noticeable odor of ammonia is one of the benefits to serve as an alarm that immediate action is required.

    Natural gas, which is used extensively as an energy source for heating has an odor added to it so that the leaks can be noticed and action taken. Based on the same logic presented, would you advocate everyone removing their furnaces from their homes?

    Natural gas without the odor added might be classified as "silent-but-deadly".

    Many, if not all of the other refrigerants you seem to promote fall into this classification also. They have no noticeable odor and would not serve to warn anyone present an immediate danger to continued life is present. The odor added to natural gas therefore improves the recognition of a situation that requires immediate action.

    Ammonia refrigeration systems have been under increased risk management scrutiny with the advent of PSM legislation also. While these mandates are typically geared towards listed chemical compounds, the same logic could be applied to those refrigerants reportedly deemed safe.

    Any refrigerant should be treated with respect and care as you would handle anything that can cause harm or injury.

    While accidents do happen in many fields, it is unfortunate the ones deemed spectacular by outside parties receive undue attention by dissemination of incomplete or inaccurate statements.

    Best regards,

    Mike Fisher

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