HOW FIRE IS CONTROLLED 



137 



Bureau of Mines Technical Papers 

 No. 97, Saving Fuel in Heating a House 

 No. 208, How to Improve the Hot-Air Furnace 



WHAT YOU SHOULD AIM TO ACQUIRE FROM 

 THIS STUDY 



1. An understanding of how heat is transferred from 

 one place to another by conduction, convection, and 

 radiation. 



2. Skill in taking care of the heating devices in your 

 own home economically. 



3. Knowledge of the construction and operation of 

 hot-air furnaces, hot-water heating plants, steam 

 heating plants. 



TEST OF MASTERY OF THE TOPIC 



In your notebook complete the statements, answer the 

 questions, and comply with the instructions. 



1. In what three ways is heat distributed from one place 

 to another? 



2. The heat from a hot-air furnace travels mainly by 



substance, the process is called 



5. The transference of heat by currents is called _ 



6. The transference of heat from one place to another 



without the aid of through a medium called is 



called radiation. 



7. The system of heating is the cheapest to install. 



8. Which of these two systems is cleaner, hot-air or 

 hot-water ? 



9. Which system provides the better ventilation in a 

 house, hot-water or hot-air? 



10. In what ways do steam and hot-water heating sys- 



are the best conductors of heat en- 



3. The heat from the sun reaches the earth by . 



4. When heat travels from molecule to molecule in a 



terns differ? 



11. In general, . 

 ergy. 



12. Suggest a reason for not making radiators used in 

 steam or hot-water heating systems from polished metal. 



13. Hot-water and steam radiators are frequently painted 

 with aluminum paint. Criticize this practice from the point 

 of view of heating efficiency. 



14. The bar of a thermostat is made of metals. 



One of these more rapidly than the other, thus mak- 

 ing the bar tend to 



15. What are the three factors to be considered in air 

 conditioning? 



16. Explain what relative humidity is and how it is de- 

 termined. 



TOPIC 4. HOW FIRE IS CONTROLLED AND PREVENTED 



SUGGESTED PROBLEMS AND QUESTIONS 



1. What is meant by kindling temperature? 



2. How did our forefathers light their fires? 



3. What are the scientific principles underlying 

 the match? 



4. How may fires be controlled? 



5. How is a fire extinguisher constructed and 

 operated? 



r-PAPEH 



r-wooD 



SULPHUR 



-PHOSPHORUS 



SHrtl 



IRON 



FIG. 218 



SUGGESTIONS AND HELPS FOR STUDY 



1. Carefully study the problems to see if they in- 

 volve questions which you have wondered about or 

 are interested in. 



2. Much of the material in this topic is largely in- 

 formational and will require considerable reading 

 from special references. 



3. Some of the material for problem 4 you should 

 be able to gather from your own experiences and ob- 

 servations. 



4. In connection with problem 5 find out what ma- 

 terials are necessary to make a fire extinguisher. The 

 materials are inexpensive and your teacher will help 

 you find them. 



EXPERIMENTS OR DEMONSTRATIONS WHICH WILL 



HELP ANSWER THE PROBLEM QUESTIONS 1 

 Experiment 95. Do different substances have different 



kindling temperatures? 



Obtain a small piece of each of the following sub- 

 stances : wood, paper, sulphur, and phosphorus. (Be very 



1 See workbook, p. 48. 



careful in handling phos- 

 phorus as it burns readily. 

 Handle it only with for- 

 ceps.) Set up apparatus as 

 shown in Figure 218. Light 

 the Bunsen burner and ob- 

 serve carefully what hap- 

 pens. Which substance 

 started to burn first? List 

 the substances in the order 

 in which they started to 

 burn. How do you explain 

 this? 



Activity 96. What are the common causes of fire? 



Uncontrolled fire causes losses of millions of dollars to 

 our nation each year. It is important that every citizen of 

 our country know what the causes of fire are and how 

 to prevent them. Investigate this problem and make a tabu- 

 lation showing causes of fire and methods of preventing 

 fires from the causes named. 



Experiment 97. How is a fire extinguisher made and 

 operated? 



A small model fire extinguisher is easy to make. Find 

 a wide-mouthed bottle of about 

 a quart capacity. Dissolve 

 two tablespoonfuls of baking 

 soda (bicarbonate of soda) in 

 a pint of water and pour in- 

 to the quart jar. Fill a small 

 test tube with dilute sulphuric 

 acid and place it inside the 

 quart bottle as shown in Fig- 

 ure 219. Place the cork with 

 a piece of glass tubing in the 

 bottle. The extinguisher is now 

 ready to use. Invert the bottle 



TEST TU6E 



SULPHURIC ACID 



SOLUTION OF 

 BAKINO SODA 

 IN WATE 



FIG. 219 



