What is needed for a fire to spread?
Heat. A heat source is responsible for the initial ignition of fire, and is also needed to maintain the fire and enable it to spread. Heat allows fire to spread by drying out and preheating nearby fuel and warming surrounding air.
How is flame spread measured?
From these observations a flame spread rating can be calculated. For example, if the flame travels 19-1/2 feet in less than 5-1/2 minutes (the time required for flame to spread on 19-1/2 feet of red oak), the rating is 100 times 5-1/2 divided by the time (minutes) in which flame spreads 19-1/2 feet on the sample.
What 4 things control the spread of a fire?
Oxygen, heat, and fuel are frequently referred to as the "fire triangle." Add in the fourth element, the chemical reaction, and you actually have a fire "tetrahedron." The important thing to remember is: take any of these four things away, and you will not have a fire or the fire will be extinguished.
What is flame spread testing?
Flame spread tests aim at measuring the tendency of a flame to propagate over a substrate and directly correlate to surface flame propagation in a real fire scenario.
How do combustible materials catch fire?
Conduction – Fire spreads through direct contact between materials. Materials like metal that are good conductors absorb the heat from the fire and pass this throughout the molecules of the material. This can cause any combustible materials that come into contact with the item to ignite.
When fire is spread from object to object it is known as?
Flashover. This method of fire spreading is closely linked to convection. Flashover happens when hot air from a fire rises to the top of a room which then radiates enough heat for objects in the room to heat up. As furniture and other objects get hot, they will begin to give off flammable gases.
How does flame spread work?
This test method measures flame growth on the underside of a horizontal test specimen, using the Steiner tunnel test. The result is derivation of a Flame Spread Index (FSI), which is a non-dimensional number which is placed on a relative scale in which asbestos-cement board has a value of 0, and red oak wood has 100.
What is the standard test methods for Surface burning Characteristics of building materials?
The ASTM E-84 is the standard test method for assessing the surface burning characteristics of building products to explore how the material might contribute to flame spread in the event of a fire. The test reports the Flame Spread index and Smoke Developed index of the tested product.
What factor influences fire spread more than any other?
Moisture level is the most important consideration. Live trees usually contain a great deal of moisture and dead logs contain very little. The moisture content and distribution of these fuels define how quickly a fire can spread and how intense or hot a fire may become.
How do you test fire resistance?
Fire resistance can be determined through destructive fire testing designed to replicate the product's intended end-use. The specimen to be tested is built into an appropriate supporting construction which is then built into a restraint frame and mounted on the front of a furnace.
What determines flammability?
Flammability is determined by the flash point of a material. Flash point is the minimum temperature at which a liquid forms a vapor above its surface in sufficient concentration that it can be ignited. Flammable liquids have a flash point of less than 100°F. Liquids with lower flash points ignite easier.
How do fires typically spread?
The heat from the fire can heat the air, to a very hot temperature. Hot air will always rise and it will flow under the ceiling of a room spreading the heat from the fire. This is the main way in which a fire spreads throughout a house.
Why do flames spread more rapidly on thin materials?
Why do flames spread more rapidly on thin materials? The thinner the material the faster it can brought to its ignition condition.
What is Class A flame spread rating?
Flame spread classifications are developed using the American Society for Testing and Materials (ASTM) “tunnel test.” Class A fire ratings indicate flame-spread of 0-25 and smoke developed between 0-450 and is the highest of the ratings. The Class A or Class I rating indicates superior fire protection.
What is the NFPA 701 test?
This test measures the flammability of a fabric when it is exposed to specific sources of ignition. NFPA 701 (Small Scale) testing measures the ignition resistance of a fabric after it is exposed to a flame for 12 seconds. The flame, char length, and flaming residue are recorded.
What are the main factors that influence fire spread and behavior?
Three factors typically influence fire behaviour: weather, fuels and topography.
What factor influences fire spread more than any other quizlet?
Wind is one of the most important influences on fire behavior. A north facing slope aspect will have more fire activity than a south facing slope aspect.
What methods are used to determine and calculate fire resistance of building materials?
The fire resistance test method used throughout the United States is ASTM E119, Standard Test Method for Fire Tests of Building Construction and Materials. Similar test methods are published by Underwriters Laboratories (UL) and by the National Fire Protection Association (NFPA).
How can you determine the level of fire resistance of materials for the build?
Fire resistant building materials are usually determined by a fire resistance rating. Under the Building Code of Australia (BCA), a Fire Resistance Level (FRL) is the grading period in minutes of the following three criteria: structural adequacy, integrity and insulation.
What makes a material combustible?
A material is considered combustible if it has a flash point higher than 37.8 ºC and below 93.3 ºC. Flammable and combustible materials will generate vapours when exposed to a temperature at, or above, its flash point, which can easily ignite when exposed to an ignition source.
What are properties of combustible materials?
6.1.1 Properties of Flammable and Combustible Liquids To control these potential hazards, several properties of these materials, such as flashpoint, vapor pressure, vapor density, compatibility, combustible (explosive) range, boiling point and auto ignition temperatures must be understood.
What are the factors that affect the spread of fire?
Many factors govern a wildfires' behavior. Weather includes wind, temperature, cloudiness, moisture and air pressure. High temperatures and low humidity cause vegetation to dry and wildfires to burn rapidly. Wind not only moves wildfires across landscapes, but also supplies oxygen that can cause fires to grow swiftly.
Why does oxygen make fire bigger?
Surface area: The bigger the area of the surface of the fuel, the more oxygen molecules can collide with the surface. The more oxygen molecules that collide per second with the fuel, the faster the combustion reaction is. You can increase the surface area of a solid by breaking it up into smaller pieces.
What is the best flame spread rating?
A class 1 fire rating is the best fire rating of materials that can be achieved. Class A fire ratings indicate a flame spread rating somewhere between zero and 25. Materials that fall into Class A or Class 1 include things like brick, gypsum wallboard, and fiber cement exterior materials.
What NFPA 703?
NFPA 703 provides enforcers, engineers, and architects with the industry's most advanced criteria for defining and identifying fire retardant-treated wood (FRTW) and fire-retardant coatings for building materials.
What NFPA 702?
NFPA 702: Standard for Classification of the Flammability of Wearing Apparel.
What determines fire behavior?
Fire needs three elements to grow: fuel, oxygen and heat. A fire can sustain itself if these three elements are present, but the amount and condition of each will determine the behavior of the fire. More fuel, hotter and drier conditions, and wind to push oxygen toward the fire all increase fire behavior.
What factors influence fire spread more than any other?
Moisture level is the most important consideration. Live trees usually contain a great deal of moisture and dead logs contain very little. The moisture content and distribution of these fuels define how quickly a fire can spread and how intense or hot a fire may become.
Which of the following fuel characteristics contribute to fire spread?
The correct answers are a and c. Conduction/radiation within the fuel bed dominate heat transfer and are the primary factors affecting fire spread.
How do you test fire resistance of a material?
The test method involves mounting the structural component in a load bearing restraint frame. The test specimen is introduced to the furnace and acts as one side of the furnace and may be mounted in a vertical (bulkhead) or horizontal (deck) orientation.