Safety & Security
Page 4
Liquid fuels like alcohol are easy to ignite because of their physical characteristics such as boiling point, flash point, vapor pressure, etc. Vapors coming off the liquid mix with the ambient air in the correct proportions and when they come into contact with an ignition source, ignite. It takes less energy and time for a liquid to become ignited.
Gases, like propane, are the easiest to ignite. Gases represent the most dangerous fuels because they have the ability to readily mix with ambient air. If they come into contact with an ignition source when mixed in the correct proportions (within in their flammable or explosion ranges) the outcome can be catastrophic.
Oxygen one of the other necessary elements for combustion, is naturally occurring in the atmosphere. The air that surrounds us contains approximately 21% oxygen. Oxygen is needed for both breathing and combustion. If the oxygen concentration level drops below 9% we can suffer unconsciousness and at levels below 6% we will suffer death in a matter of minutes. Like us the combustion process is also affected by the concentration of oxygen available. The free-burning phase of combustion can occur between 21% and 16% concentration. If the oxygen level drops below 14% concentration a smoldering phase of combustion develops or extinguishment occurs.
Heat has to be present in sufficient quantity for ignition to begin the combustion process. Heat energy is also a by-product of the combustion process. It provides the physical properties that the fire will need to intensify and spread. Unfortunately, heat energy posses the greatest threat of injury to individuals in the immediate area of the fire. Individuals dressed in normal work clothing trying to extinguish an incipient stage fire may or may not be affected by the heat that is being produced by the fire. However, staff should be aware that it is not uncommon for the temperature in the flame column near the base of the fire to exceed 1000°F. Individuals in the operating room in which the fire is occurring may feel some physical discomfort from the heat but will be more affected by the smoke that is being generated at least in the initial stages of a fire.
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