How Things Burn. fire triangle. oxygen

Transcription

1 RANGERS will be able to: a. Describe the three things needed to create fire; b. Describe the fire triangle; c. Name at least three fuels and three heat sources likely to be found in forests. Appropriate for ages 8-12 Overview: In this activity, RANGERS build a model of the fire triangle, learn about its components, and then apply their fire triangle knowledge to a typical forest landscape to practice identifying fuels and heat sources. This lesson suggests several instructor demonstrations that can be used to enhance RANGER learning. Background Information: The fire triangle is a model that includes three things needed for fire to burn fuel, heat and oxygen. he a t el fu fire triangle F uel is something that will burn to produce energy, like wood or gasoline. Materials Needed: (Copy as Needed) Heat is a kind of energy that causes a rise in temperature. RANGER Pages O xygen is a colorless, odorless gas that is essential for almost all life. It makes up 21% of the air we breathe. The interaction of these three elements is required for the creation and maintenance of any fire. When there is not enough heat generated to sustain the process, when the fuel is exhausted, removed, or isolated, or when the oxygen supply is limited, then a side of the triangle is broken and the fire is extinguished. The following RANGER pages will help RANGERS apply the fire triangle to forests and wildfires. For example, forests contain fuel and oxygen. If you add a heat source, a wildfire could start. Knowledge of the fire triangle is important for recognizing the fire potential and risks that objective glass jar with lid matches or lighter candle Pencils or pens Modeling Clay popsicle sticks colored markers threaten lives, property and resources. oxygen 2-1

2 More About Fire Activity Sequence: 1. Prepare for this activity by placing a candle in the lid of a glass jar. The candle should be short enough so that when the jar is screwed on, the flame will not heat up the jar too much. (Before you light the candle, make sure the area is well-ventilated and that you will not set off a smoke alarm. Also, you should have already made sure it is permissible to have an open flame in the room. Consider doing this part of the activity outdoors.) 2. Ask RANGERS how many have seen a large fire. Have them describe what they saw. If you have photos or a video of a wildfire, this is a good time to show it. 3. Ask RANGERS what they think is needed for a fire to burn. Place the jar on the upside down lid with the candle and tighten it without saying anything. When the candle goes out, ask them to answer question A on RANGER Page 2-5 (the fire goes out when all the oxygen in the jar is used up by the fire). Note: the jar may be hot so don t let RANGERS touch it, and you may want to handle it with a glove. 6. Distribute the materials to build a model of the fire triangle. Have RANGERS write the names of the sides of the fire triangle (oxygen, heat, fuel) on three popsicle sticks. 7. Have RANGERS make balls of modeling clay to secure the popsicle sticks into a triangle. 8. Emphasize that each side of the fire triangle must be present for fire to occur. One important aspect of wildfire PREVENTION is to remove one or more sides of the fire triangle. This is difficult to do where oxygen is concerned (since it would require the absence of air), so a big part of fire prevention is keeping fuels and heat sources from being in contact with each other. Long ago, humans believed fire was one of the four elements that made up everything they saw around them: earth, air, water, and fire. Humans have since discovered 112 elements that make up the things we see around us. Fire is really a mixture of hot gasses - the result of a chemical reaction, primarily between oxygen in air and a fuel (such as wood or gasoline). The oxygen atoms combine with atoms in the fuel being burned. The atoms get excited as they are heated, usually from an external source such as a match. As the heat increases, atoms of oxygen, carbon and hydrogen in the wood fly apart, and oxygen in the air combines with these atoms and molecules, making new molecules such as water, carbon dioxide, methane, and producing heat, light and sound. As long as there is fuel,(such as wood), heat and oxygen, the fire will keep burning. 4. Lead a discussion of what happened in the jar. Before moving on, make sure everyone understands what oxygen is and how it affects fire. Help them understand that oxygen is a colorless gas in the air we breathe. 5. Once everyone understands the three things needed for a fire to burn oxygen, heat, and fuel introduce the concept of the fire triangle. Emphasize that the fire triangle applies to all fires. 2-2

3 9. Now take the fire triangle model a step further. Describe two common fires a lit candle and a campfire. Have RANGERS fill in the table in c on RANGER Page 2-5 as you lead the discussion. A completed table should look like this: Item Oxygen Source Heat Source Candle air match or lighter Campfire air match or lighter Fuel Source wax and wick firewood Candles: A candle is made of wax surrounding a wick. The wick burns when the candle is lit. The heat turns the wax coating into a vapor (gas). The vapor combines with oxygen, and burns. Campfires: Campfires use wood as the fuel to keep campers warm, roast hot dogs, or toast marshmallows. Paper or kindling (also wood products) is often used to start the fire, since it is easier to ignite than large logs. 10. Discuss the answers from c on RANGER Page 2-5. Make sure RANGERS understand that there can be many fuels and heat sources in any one place. 11. Tell RANGERS that they will now look at a typical forest landscape drawing. Their task in d on RANGER Page 2-5 is to identify as many fuels and heat sources as they can from the drawing. Have them list the heat sources and fuels in the table on the RANGER Page 2-7. heat Sources oxygen sources fuel sources matches air cigarettes/cigars sparks/heat from car or truck exhaust sparks or embers from burning debris campfire charcoal briquettes sparks/heat from motorcycle sparks from chain saw trees brush dry needles, twigs leaves on ground grass gas in can BBQ fuel 12. Distribute the landscape drawing to each RANGER, or pair of RANGERS. Have RANGERS read the introduction and begin the activity. Listed below are many of the heat and fuel sources RANGERS may see they might identify more! Have RANGERS compare lists with each other. Many fuels and heat sources can be found in forest areas, and all can potentially create wildfires. Many of these fuels and heat sources may also be found around RANGERS homes, and safety should be practiced at home to keep fuels away from heat sources there as well. 2-3

4 Additional Resources green.org/ 13. Have RANGERS look at the drawing again. Ask them if they can spot at least two things that could break down the fire triangle (help put out a fire). Have them fill in e and f on RANGER Page 2-7. They may come up with some of the following: 1. shovel (to shovel dirt onto the fire, separating the heat source and fuel sources from the oxygen source) 2. water (to cool the fire, removing the heat source) 3. fire extinguisher (to smother the fire, removing the oxygen and also cooling the heat) 14. Ask RANGERS if they can spot anything else in the drawing that might help prevent wildfires, and have them complete f on RANGER Page 2-7. The Keep Oregon Green sign could remind people to be careful with fire in forests. Review Questions 1. Can anyone describe a fire triangle by using three other RANGERS, each playing the part of one side of the fire triangle? (One RANGER should assign a part to three RANGERS and then have them clasp hands to form a triangle. 2. Have one of the RANGERS drop hands and move away from the fire triangle. What would happen to the fire? 3. What fuels are often found in forests? 4. What are three heat sources often found in forests? wiki/fire_triangle modules/fire/01_triangle. htm gov/education/ LearningLandscapes/ explorers/lifetime/fire. html kids/ 5. What are two things that you could take or use in forests to prevent wildfires? 2-4

5 The Mystery of the Candle Candles and Campfires a. T he candle burned for a short time after the lid was tightened. Why did the candle finally go out? c. F ill in the table below as your instructor discusses the fuels, heat sources, and oxygen sources needed for candles and campfires to burn: Here s what you will need to build your fire triangle model: markers modeling clay oxygen Source heat source fuel source Seeing the Fire Triangle in Forests Forests are full of many fuels and lots of oxygen. Add a heat source, and you could start a wildfire. Building a Fire Triangle Model popsicle sticks ITEM Candle Campfire d. E xplore the drawing of a typical Oregon forest landscape on the next page. In forests, oxygen is always present. How many sources of fuel and heat can you identify in the forest landscape pictured on page 2-6? Write them in the table on page 2-7. b. Write the names of the sides of the fire triangle on the three popsicle sticks. Make balls of modeling clay to form a triangle with the popsicle sticks. 2-5

6 el he at fu fire triangle oxygen 2-6

7 List heat and fuel sources you see on the landscape drawing on RANGER Page 2-6 below. Heat Sources fuel sources e. C an you spot at least three things in the drawing that could help you remove the parts, or sides, of the fire triangle (prevent or put out a fire)? Describe how each item would break down the fire triangle f. W hat else can you spot in the drawing that might help prevent a wildfire? 2-7