Ammonia As a Refrigerant: Pros and Cons

In March 2016, a 5000-pound ammonia leak occurred at a Boston-area seafood warehouse that killed one worker and forced a shelter-in-place order from Boston Police.  Problematic procedures may be to blame. So as you read the pros and cons of Ammonia as a refrigerant below, remember these key takeaways: ongoing, scheduled evaluations and preemptive maintenance are critical for any ammonia storage solution — lax procedures place workers and residents in danger.

Why is Ammonia growing in popularity given this risk? As fewer and fewer CFCs and HCFCs are available for use as refrigerants, companies are looking to ammonia as a more effective replacement. According to ASHRAE and the International Institute of Ammonia Refrigeration (IIAR), ammonia is a cost-effective, efficient alternative to CFCs and HCFCs that is also safe for the environment.

Ammonia (chemical formula NH3) is a gas comprised of two other gases — nitrogen and hydrogen. Whether found in nature or made by man, ammonia is colorless but has a sharp, pungent odor. Ammonia, frequently used commercially in large freezing and refrigeration plants is also called “anhydrous ammonia” because it contains almost no water (it is 99.98% pure). Household ammonia, by comparison, is only about 10% ammonia by weight mixed with water.

As a refrigerant, ammonia has four major advantages over CFCs and HCFCs:

• An ammonia-based refrigeration system costs 10-20% less to build than one that uses CFCs because narrower-diameter piping can be used.
• Ammonia is a 3-10% more efficient refrigerant than CFCs, so an ammonia-based system requires less electricity, resulting in lower operating costs.
• Ammonia is safe for the environment, with an Ozone Depletion Potential (ODP) rating of 0 and a Global Warming Potential (GWP) rating of 0.
• Ammonia is substantially less expensive than CFCs or HCFCs

There are two key disadvantages to using ammonia as a refrigerant:

• It is not compatible with copper, so it cannot be used in any system with copper pipes.
• Ammonia is poisonous in high concentrations. Two factors, however, mitigate this risk: ammonia’s distinctive smell is detectable at concentrations well below those considered to be dangerous, and ammonia is lighter than air, so if any does leak, it will rise and dissipate in the atmosphere.

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