Fires: Mechanism: (c) At atmospheric pressure the boiling point of water is 100°C (212°F) - liquid water at atmospheric pressure cannot exist at temperatures higher than 100°C (212°F). It is obvious, then, that 204. 4°C (400°F) liquid water at atmospheric pressure must immediately flash to gas causing an explosion. It is important to note that a BLEVE need not be a chemical explosion - there does not need to be a fire - however if a flammable substance is subject to a BLEVE it may also be subject to intense heating, either from an external source of heat which may have cause the vessel to rupture in the first place or from an internal source of localized heating such as skin friction. This heating can cause the substance to ignite, adding a secondary explosion caused by the primary BLEVE. While any BLEVE can be extremely devastating, a flammable substance such as propane can add significantly to the danger. While the term BLEVE is most often used to describe the results of a container of flammable liquid rupturing due to fire, a BLEVE can occur even with a non-flammable substance such as water, liquid nitrogen, liquid helium or other refrigerants or cryogens, and therefore is not usually considered a type of chemical explosion