Chapter 19 - I Didn't Know That ♦ ♦ ♦

Abstract

Some accidents occur because people are unaware of events that had happened many times before. Accidents occurring due to ammonia catching fire or causing explosions, carbon dioxide igniting a flammable mixture, hazardous hydraulic pressure tests, leaks catching fire in diesel engines, and mists causing explosions are highlighted in this chapter. In reports on ammonia explosions, it is found that ammonia can explode. For example, a leak of ammonia from the 50-year-old refrigeration system of an ice cream plant in Houston, Texas, ignited and severely damaged the building. Nevertheless, some spectacular failures have occurred during hydraulic tests. As water is incompressible, hydraulic pressure tests are often considered safe. If the vessel fails, the bits will not fly far. Hydraulic pressure testing is safer than pneumatic testing, as much less energy is released if the equipment fails but has sometimes resulted in major accidents that are also described in this chapter. Most companies do not allow spark ignition (gasoline) engines to enter areas where flammable gases or liquids are handled, except under strict control, as a leak of gas or vapor might be ignited by the spark mechanism. Many companies, however, allow uncontrolled access by diesel engines, believing that they cannot ignite gas or vapor, which is incorrect. Various examples of carbon dioxide resulting in fires and mist causing explosions are also described in the chapter. Almost everyone knows that dusts—fine particles of a solid—can explode, but not everyone is aware that mists—fine droplets of a liquid—can explode just as easily and that they can explode at temperatures far below the flash point of the bulk liquid or vapor.