As natural refrigerant ammonia is toxic and slightly flammable, safety is crucial to its market success. Here are some measures that can be taken.
Ammonia (NH3), an environmentally friendly natural refrigerant, has played a crucial role in the HVAC&R sector since the 1850s. As a toxic chemical with a relatively low flammability threshold, adequate safety measures are essential to guarantee its safe use.
ASHRAE classifies NH3 as a B2L refrigerant. Prolonged contact with it or a high concentration of it in the air can lead to fatal injuries. Taking adequate safety measures and following best practices are crucial to its successful use.
The U.S. Environmental Protection Agency (EPA) states that most reported accidents could have been preventable with basic safety procedures and better training of personnel.
“72% of all reported chemical accidents in Iowa, Kansas, Missouri, and Nebraska involve anhydrous ammonia. Up to 96% of them are preventable through increased operator training, improved procedures, and better communication of lessons learned.” – EPA
Safety Links, an IOA (Insurance Office of America) company, urges everyone working with the refrigerant to be adequately trained to ensure safety. Staff should wear Personal Protective Equipment (PPE) at all times as well.
British company Fisher Chemicals suggests that workers wear protective gloves and clothing as well as protection for the eyes and face. Equipment should be checked before it is used.
“The chemical that posed an immediate hazard to the health and safety of workers at the plant was ammonia. You can avoid this kind of incident in your workplace by training your workers on how to work safely […].” – Safety Links
System manufacturer GEA notes that it is mandatory in Europe for all personnel working with ammonia compressor units or liquid chillers to be adequately trained and qualified. The company also states that the facility operator must approve anyone working with NH3. Instructions on how to handle the refrigerant must be given regularly, and communicated to the authorities.
No technician should work with the refrigerant alone, according to Canadian safety instrumentation firm Enviro2Med. A colleague can provide first aid in the case of an accident. The correct measures to be taken in such situations will be outlined in Part 2 of this article.
The EPA suggests that companies draw up policies on NH3, and that Recognised And Generally Accepted Good Engineering Practices (RAGAGEP) should be developed and implemented. This includes not undertaking any brazing, repair work, or other high-risk activities before the equipment has been completely purged, among other safety measures.
The agency also urges companies to conduct a Process Hazard Analysis (PHA) to identify, evaluate and control any potential danger that exists in the facility. All identified issues can potentially cause an accidental ammonia release. A PHA should be done every five years or when there is a major change in the system.
Maintenance of the refrigeration system must be conducted and documented daily. Visual inspections are inexpensive and offer insights into abnormalities that could lead to accidents. Some companies thermally check the system to detect hot spots that may cause failure before they can be seen. All tools and piping insulation must be inspected visually as well.
Selecting the right equipment is equally as crucial as ensuring that personnel are well trained. Systems must be designed in a way that minimises the danger of a leak. For example, all parts of the refrigeration circuit need to be hermetically sealed, and the complete system should to be secured from falling objects.
In addition, NH3 must be carried only in specialised equipment to prevent cylinders from breaking, and only specialists should handle damaged cylinders; the EPA strongly advises regular technicians not to open them.
“Forklifts, hand trucks, and other maintenance vehicles can and have caused […] releases after damaging unprotected components of ammonia refrigeration systems. It is good practice to provide barriers or establish safety procedures to protect refrigeration equipment […].”– EPA
Due to the refrigerant’s slight flammability, it has to be kept away from ignition sources such as hot surfaces or sparks, for example from electric switches.
The owner of the facility is urged to install ventilation in all areas where NH3 could leak. This prevents the refrigerant from reaching a potentially dangerous concentration in the air. Safety Links advises technicians not to work in unventilated rooms.
The ventilation and the exhaust openings must be placed in a way that ensures the airflow does not damage human health. As it is lighter than air, GEA advises placing the openings near the ceiling.
Special detectors should be installed everywhere a leak could occur. They should trigger an alarm set at a reasonable level.
Last, but not least, good communication is crucial to reducing the chance of safety incidents, and companies should embrace a culture that focuses on learning from mistakes instead of punishing them. Technicians who are confident in admitting their mistakes can help to prevent future problems from happening and thus reduce the risk of serious accidents.
If all the right measures are taken, the refrigerant is safe to use. The key points are frequent checks of the system, protecting the system from external damage, a well-adjusted alarm system and, importantly, a company culture that encourages reporting mistakes and learning from them.
Part 2 of ammonia safety will discuss the right actions to be taken in case of an emergency. Below, you can find more news addressing safety issues with this refrigerant.
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