Text of Pumping Apparatus Driver/Operator — Lesson 6 Pumping Apparatus Driver/Operator Handbook, 2 nd...
Pumping Apparatus Driver/Operator Lesson 6 Pumping Apparatus Driver/Operator Handbook, 2 nd Edition Chapter 6 What Is Water and Where Does It Come From?
Pumping Apparatus Driver/Operator 6161 Learning Objectives 1.Select facts about the characteristics of water. 2.List the ways in which water has the ability to extinguish fire. 3.Answer questions about specific heat. 4.Select facts about latent heat of vaporization. (Continued)
Pumping Apparatus Driver/Operator 6262 Learning Objectives 5.Calculate latent heat of vaporization. 6.Answer questions about the surface area of water. 7.Explain the ways in which water smothers fire. 8.Select facts about specific gravity. (Continued)
Pumping Apparatus Driver/Operator 6363 Learning Objectives 9.List advantages of water as an extinguishing agent. 10.List disadvantages of water as an extinguishing agent. 11.Distinguish between pressure and force. 12.Explain how force is determined. (Continued)
Pumping Apparatus Driver/Operator 6464 Learning Objectives 13.State the principles of fluid pressure. 14.Match to their definitions terms associated with pressure. 15.Explain how to measure atmospheric pressure. 16.Calculate head pressure. (Continued)
Pumping Apparatus Driver/Operator 6565 Learning Objectives 17.List causes of friction loss in fire hose. 18.List causes of friction loss in piping systems. 19.List the principles of friction loss. 20.Answer questions about other factors affecting friction loss. (Continued)
Pumping Apparatus Driver/Operator 6666 Learning Objectives 21.List ways to reduce friction loss. 22.Select facts about water hammer. 23.Name the four primary components of a municipal water system. 24.Answer questions about the primary components of a municipal water system. (Continued)
Pumping Apparatus Driver/Operator 6767 Learning Objectives 25.Select facts about water main valves. 26.Answer questions about water pipes. 27.Match to their definitions water system consumption rates. 28.Select facts about private water supply systems. (Continued)
Pumping Apparatus Driver/Operator 6868 Learning Objectives 29.List the purposes of a private water supply system. 30.List the advantages to have separate piping arrangements in a private water supply system.
Pumping Apparatus Driver/Operator 6969 Characteristics of Water Water is a compound of hydrogen and oxygen formed when two hydrogen atoms (H 2 ) combine with one oxygen atom (O). Between 32F and 212F (0C and 100C), water exists in a liquid state. (Continued)
Pumping Apparatus Driver/Operator 610 Characteristics of Water Below 32 F (0C) (the freezing point of water), water converts to a solid state called ice. Above 212F (100C) (the boiling point of water), water converts into a gas called water vapor or steam; it cannot be seen. (Continued)
Pumping Apparatus Driver/Operator 611 Characteristics of Water (Continued)
Pumping Apparatus Driver/Operator 612 Characteristics of Water Water is considered to be incompressible, and its weight varies at different temperatures. Note: Water is measured in pounds per cubic foot (kg/L) (Continued)
Pumping Apparatus Driver/Operator 613 Characteristics of Water Water is heaviest close to its freezing point, weighing approximately 62.4 lb/ft 3 (1 kg/L) Water is lightest close to its boiling point, weighing approximately 60 lb/ft 3 (0.96 kg/L) For fire protection purposes, ordinary fresh water is generally considered to weigh 62.5 lb/ft 3 or 8.33 lb/gal (1 kg/L)
Pumping Apparatus Driver/Operator 614 Ways in Which Water Extinguishes Fire Cooling By absorbing heat from the fire Smothering Water can be used to smother fires in combustible liquids whose specific gravity is higher than 1. Smothering also occurs to some extent when water converts to steam in a confined space.
Pumping Apparatus Driver/Operator 615 Specific Heat The heat-absorbing capacity of a substance Amounts of heat transfer are measured in British thermal units (Btu) or joules (J) A Btu is the amount of heat required to raise the temperature of 1 pound of water 1F. The joule has taken the place of the calorie (1 calorie = 4.19 joules). (Continued)
Pumping Apparatus Driver/Operator 616 Specific Heat Is the ratio between the amount of heat needed to raise the temperature of a specified quantity of a material and the amount of heat needed to raise the temperature of an identical quantity of water by the same number of degrees. Of different substances varies. Refer to Table 6.1 on p. 136 of the manual.
Pumping Apparatus Driver/Operator 617 Latent Heat of Vaporization Is the quantity of heat absorbed by a substance when changing from liquid to vapor. The temperature at which a liquid absorbs enough heat to change to vapor is known as its boiling point. At sea level, water begins to boil or vaporize at 212F (100C). (Continued)
Pumping Apparatus Driver/Operator 618 Latent Heat of Vaporization Vaporization does not completely occur the instant water reaches the boiling point. Each pound of water requires approximately 970 Btu (1 023 kJ) of additional heat to convert completely to steam. (Continued)
Pumping Apparatus Driver/Operator 619 Latent Heat of Vaporization The latent heat of vaporization is significant in fire fighting because the temperature of the water is not increased beyond 212F during the absorption of the 970 Btu for every pound of water.
Pumping Apparatus Driver/Operator 620 Surface Area of Water The speed with which water absorbs heat increases in proportion to the water surface exposed to the heat. (Continued)
Pumping Apparatus Driver/Operator 621 Surface Area of Water Water expands when converted to steam. At 212F (100C), water expands approximately 1,700 times its original volume. (Continued)
Pumping Apparatus Driver/Operator 622 Surface Area of Water Steam expansion is rapid inside a burning building. The use of a fog stream in a fire attack requires that adequate ventilation be provided ahead of the hoseline.
Pumping Apparatus Driver/Operator 623 Ways in Which Water Smothers Fire By floating on liquids Water floats on liquids that are heavier than water. If the material is water soluble, the smothering action is not likely to be effective. By forming an emulsion Water smothers fire by forming an emulsion over the surface of certain combustible liquids. (Continued)
Pumping Apparatus Driver/Operator 624 Ways in Which Water Smothers Fire By forming an emulsion When a spray of water agitates the surface, the agitation causes the water to be suspended in emulsion bubbles on the surface; the emulsion bubbles smother the fire. Emulsion bubbles can only form when the combustible liquid has sufficient viscosity the tendency of a liquid to possess internal resistance to flow.
Pumping Apparatus Driver/Operator 625 Specific Gravity The density of liquids in relation to water Water is given a value of 1. Liquids with a specific gravity less than 1 are lighter than water and float on water. Those with a specific gravity greater than 1 are heavier than water and sink to the bottom. Most flammable liquids have a specific gravity of less than 1.
Pumping Apparatus Driver/Operator 626 Advantages of Water as an Extinguishing Agent Water has a greater heat-absorbing capacity than other common extinguishing agents. A relatively large amount of heat is required to change water to steam. This means that more heat is absorbed from the fire. (Continued)
Pumping Apparatus Driver/Operator 627 Advantages of Water as an Extinguishing Agent The greater the surface area of water exposed, the more rapidly heat is absorbed. The exposed surface are of water can be expanded by using fog streams or deflecting solid streams off objects. (Continued)
Pumping Apparatus Driver/Operator 628 Advantages of Water as an Extinguishing Agent Water converted into steam occupies 1,700 times its original volume. Water is plentiful, relatively inexpensive, and readily available in most jurisdictions.
Pumping Apparatus Driver/Operator 629 Disadvantages of Water as an Extinguishing Agent Water has a high surface tension and does not readily soak into dense materials. However, when wetting agents are mixed with water, the waters surface tension is reduced and its penetrating ability is increased. Water may be reactive with certain fuels such as combustible metals. (Continued)
Pumping Apparatus Driver/Operator 630 Disadvantages of Water as an Extinguishing Agent Water has low levels of opacity and reflectivity that allow radiant heat to easily pass through it. Water readily conducts electricity, which can be hazardous to firefighters working around energized electrical equipment. (Continued)