According to NFPA 520, which type of contents is described as likely to burn with extreme rapidity?

High hazard contents are characterized by their ability to burn very rapidly, which significantly increases the risk of fire spread and the potential for severe fire conditions. This classification highlights materials that possess a high degree of combustibility, contributing to intense heat release and quick escalation in fire situations. Such contents can include flammable liquids, certain types of chemicals, and other materials that ignite easily and produce fast-burning flames.

Understanding this classification is crucial for fire inspectors, as it informs their approach to fire prevention, inspection protocols, and emergency response planning. The distinction among categories, including low hazard, ordinary hazard, and hazardous materials, underscores the varying degrees of risk they present, with high hazard contents requiring the most stringent safety measures due to their rapid ignition and burning characteristics.