Final answer:
Fire requires heat as an ignition source, fuel to sustain the fire, and oxygen to support the chemical reactions during combustion. These three elements make up the fire triangle and are all necessary for fire to occur and continue burning.
Step-by-step explanation:
To occur, fire requires three essential components which are commonly referred to as the fire triangle or combustion triangle. The three components needed for a fire to occur are:
- Heat - This is the ignition source that starts the fire and is necessary to maintain the fire and enable it to spread. Heat allows fire to spread by drying out nearby fuel, preheating it, and warming the surrounding air.
- Fuel - Fuel is any kind of combustible material that the fire will consume to maintain itself. This includes a wide range of materials with varying moisture content, size, shape, and quantity. The arrangement and characteristics of the fuel determine how easily it will burn.
- Oxygen - Oxygen, which makes up about 21 percent of air, is necessary for the chemical processes involved in fire. Most fires require at least 16 percent oxygen content to burn. During combustion, fuel reacts with oxygen, releasing heat and forming new substances such as smoke, gases, and embers.
Each of these components plays a crucial role in the creation and sustenance of a fire, by enabling the necessary chemical reactions that release heat and light.