Several industries like cold storage and ice plants heavily rely on ammonia (NH3) due to its low cost, excellent thermophysical traits, and zero effects on the ozone layer. Despite its widespread use as a refrigerant, the hazardous nature of ammonia remains a significant health concern. Since the industrial revolution, ammonia leakage has led to numerous major accidents, including fire and vapor cloud explosions. This paper reviews the safety issues and the current practices of risk assessment with regard to the industrial ammonia used in refrigeration systems. In addition, previous works related to the risk analysis of ammonia-based industries are reviewed. The majority of ammonia refrigeration system-related works applied the traditional static tools for risk analysis such as fault tree, event tree, and bow-tie that are not suitable to handle common causes of failures or conditional dependencies, which are absolutely significant aspects for a reliable safety assessment. Thus, it is vital to maintain and improve the safety levels of diverse industries using ammonia-based refrigeration systems. Various characteristics of ammonia-based refrigeration systems and their safety issues related to industry, present development, and future trends are comprehensively underscored. This review may act as a guide to develop a better understanding of dealing effectively with the hazards of ammonia-based refrigeration systems and risk assessment, thus enhancing the overall safety of humans and the environment.

The explosion of dust particles poses significant risks to the health and safety of humans working in process industries such as mining, energy, and manufacturing. A dust explosion is the rapid deflagration of particles in a large volume of air or gaseous oxidants. Since industrial dust explosions can occur in any plant equipment or environment, it is crucial to identify, examine and highlight the highly probable sources and risk areas for dust cloud formation and ignition along with damage control measures. Therefore, the paper presents a concise review of the various combustion classifications of dust along with the mechanisms of dust explosion, ignitability factors, and severity characteristics, explosibility testing methods, and damage control measures. Dust is broadly classified according to its explosive value, which indicates that its moisture, particle size, dust concentration, oxidant concentration, and turbulence are crucial to a dust explosion. Furthermore, the dust explosion mechanism reveals that dust particles undergo explosion when confined and or mixed oxidants, ignition sources or heat as described in the “explosive pentagon” concept. To address the risks posed by dust explosions, reduce ignitions and the severity of these hazards, numerous testing methods have been proposed or developed. The most notable characteristics of explosion severity are the maximum explosion overpressure (Pmax), maximum rate of pressure rise (dp/dt) max, dust deflagration index (Kst), and minimum explosibility concentration (MEC). Likewise, the measures for containing, isolating, suppressing, and venting the effects of dust explosion were also highlighted in detail. In conclusion, the review highlighted the role of the particles and dust clouds and the need to identify and highlight the sources of dust explosion that pose risks to human health and safety in the industry.