Ammonia Refrigeration Safety Part 2 — Responding to an accident

Ammonia (NH₃) is a toxic and slightly flammable refrigerant, but it is safe to use when handled correctly.  

It has been employed for more than a century, and currently is prevalent in large industrial facilities around the globe. Accidents with R717 are extremely rare in relation to the volume of the refrigerant handled globally on a daily basis, 

In a white paper about safety in ammonia systems, written by Niels Vestergaard of Danfoss for the International Institute of Refrigeration (IIFIIR), he states that 29 reportable events concerning the refrigerant occurred in Germany between 1993 and 2013. These caused no fatalities, and no explosion or fire was reported., In the U.S., 1,253 releases were reported between 1994 and 2013, resulting in 18 fatalities. 

Investigations of these incidents have consistently shown a pattern of human errors, with poor maintenance and ignorance of basic safety protocols as the main causes of incidents, according to the EPA.  

The U.S.-based Ammonia Safety and Training Institute (ASTI) strongly advises that companies list these critical tasks in their guidance policy.

Basic protocols

While there is no universal protocol on handling accidental releases of NH₃, there are ample resources available that can serve as guidance, especially in the U.S., where the topic has traditionally attracted strong interest. For example, as a general recommendation, the U.S. Environmental Protection Agency (EPA) advises technicians not to work alone with the refrigerant to reduce the risk of serious injuries. 

Ammonia has a distinctive odour, meaning that accidental releases can be noticed before the concentration in the air becomes dangerous to human health. According to Enviro2Med, a Canadian safety instrumentation firm, most people detect the smell at concentrations of 0.6 to 53 ppm. At 50 ppm, ammonia is already irritating but most people experience immediate and severe irritation to the nose and throat at 500 ppm. Fatal injuries are possible at 1500 ppm. 

NH₃ tends to form a cloud that stays near the ground for a short time. This is because it becomes a vapour upon release. However, it is lighter than air, meaning that it will disperse into the sky, according to Safety & Health Magazine. 

A person exposed to R717 should seek medical attention quickly, even though some symptoms may be delayed. 

The National Institute for Occupational Safety and Health (NIOSH) in the U.S. provides information about the symptoms of exposure and how to provide first aid. Exposure may primarily affect the eyes, skin or respiratory system. 

Anyone helping in a situation where the refrigerant was released accidently is advised to call a doctor or an ambulance immediately in all cases, and bring victims to a well-ventilated area, away from the source of exposure. The decontamination area should be upwind and uphill from the site. It should also include two warm zones, one for entering and one for leaving. 

ASTI adds that a person giving first aid must wear personal protective equipment (PPE). 

Of course, the best way to protect the workforce from injuries related to accidental ammonia releases is to prevent incidents in the first place by ensuring the right level of qualifications and training for all staff involved in the design, operation and maintenance of the plant. 

For more on this topic, see Ammonia Refrigeration Safety Part 1.

Additional information can be found in the articles below:

New Zealand-based company opens online NatRef training course

Canadian city reaffirms commitment to NH₃