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Ammonia

Ammonia — the only «honest» refrigerant:

Ammonia is an environmentally compatible refrigerant because it has an ozone depletion potential (ODP) of zero and a global warming potential (GWP) of zero. No other refrigerant can claim such perfect statistics.

Because of its superior thermodynamic properties, ammonia as a refrigerant requires less energy to produce a given amount of cooling than other refrigerants.

Less than 2% of global ammonia production is used as refrigerant, and this needs to be 99.98% pure ammonia to work well.

Ammonia safety

Ammonia refrigeration has a excellent safety record and in spite of being by far the most widely used refrigerant on the planet, lags behind other common refrigerants such as R22 in accident statistics. This is in part due to its sharp and pungent odour which warns of its presence even at very low concentrations, and encourages people to leave the area before any danger exists.  No other refrigerant possesses such an effective self-alarming effect.

  • Ammonia classed as B2: Toxic and Flammable
  • Ammonia 1,7 x lighter than air and quickly rises, unlike halocarbons
  • Ammonia is difficult to ignite, and combustion only possible in narrow concentration ranges (15-18%)
  • Odour threshold 5ppm, few people can endure >50ppm
  • Threshold workplace exposure limit values
    • Time Weighted Average (TWA) 25ppm
    • Short Term Exposure Limit (STEL) 35ppm
  • Effect on Eyes:
    • 100-200ppm — eyes irritated
    • <500ppm — no permanent eye damage
  • Effect on Lungs:
    • 400ppm — immediate throat irritation
    • 1700ppm — cough
    • 2400ppm — threat to life after 30 minutes
  • Effect on Skin: 5000ppm and above requires full body suit

Code and regulatory requirements relating to ammonia

AS/NZS 1677.2 defines safety requirements for refrigeration systems, including ammonia.  As ammonia is classed as a B2 refrigerant (toxic and flammable) specific safety requirements are mandated by this code, which include:

  • Permissible charge in various locations and applications
  • Ventilation requirements for plant rooms
  • Safety and documentation requirements for installed system

The Australian building code (BCA) does not regulate or restrict the use of ammonia in any way, such that as long as compliance with AS/NZ 1677.2 is ensured, ammonia can be used as a refrigerant in commercial applications, e.g. as water chiller for air-conditioning applications.

In most states and countries Occupational Health and Safety regulations place the duty of care on operators of all refrigeration equipment, which would require regular risk assessments and safety audits to be conducted, and for safety and evacuation procedures to be maintained on each site.

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