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Pumping Apparatus Driver/Operator — Lesson 6

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?. Learning Objectives. 1. Select facts about the characteristics of water.

hoshiko-miyamoto
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Pumping Apparatus Driver/Operator — Lesson 6

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  1. Pumping Apparatus Driver/Operator — Lesson 6 Pumping Apparatus Driver/Operator Handbook, 2nd Edition Chapter 6 — What Is Water and Where Does It Come From?

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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

  10. Characteristics of Water • Water is a compound of hydrogen and oxygen formed when two hydrogen atoms (H2) combine with one oxygen atom (O). • Between 32ºF and 212ºF (0ºC and 100ºC), water exists in a liquid state. (Continued) Pumping Apparatus Driver/Operator

  11. Characteristics of Water • Below 32º F (0ºC) (the freezing point of water), water converts to a solid state called ice. • Above 212ºF (100ºC) (the boiling point of water), water converts into a gas called water vapor or steam; it cannot be seen. (Continued) Pumping Apparatus Driver/Operator

  12. Characteristics of Water (Continued) Pumping Apparatus Driver/Operator

  13. 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

  14. Characteristics of Water • Water is heaviest close to its freezing point, weighing approximately 62.4 lb/ft3 (1 kg/L) • Water is lightest close to its boiling point, weighing approximately 60 lb/ft3 (0.96 kg/L) • For fire protection purposes, ordinary fresh water is generally considered to weigh 62.5 lb/ft3 or 8.33 lb/gal (1 kg/L) Pumping Apparatus Driver/Operator

  15. Ways in WhichWater 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

  16. 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 1ºF. • The joule has taken the place of the calorie (1 calorie = 4.19 joules). (Continued) Pumping Apparatus Driver/Operator

  17. 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

  18. 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 212ºF (100ºC). (Continued) Pumping Apparatus Driver/Operator

  19. 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

  20. Latent Heat of Vaporization • The latent heat of vaporization is significant in fire fighting because the temperature of the water is not increased beyond 212ºF during the absorption of the 970 Btu for every pound of water. Pumping Apparatus Driver/Operator

  21. 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

  22. Surface Area of Water • Water expands when converted to steam. At 212ºF (100ºC), water expands approximately 1,700 times its original volume. (Continued) Pumping Apparatus Driver/Operator

  23. 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

  24. 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

  25. Ways in WhichWater 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

  26. 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

  27. Advantages of Water asan 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

  28. Advantages of Water asan 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

  29. Advantages of Water asan 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

  30. Disadvantages of Water asan 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 water’s 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

  31. Disadvantages of Water asan 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) Pumping Apparatus Driver/Operator

  32. Disadvantages of Water asan Extinguishing Agent • Water freezes at 32ºF (0ºC), which is a problem in jurisdictions that frequently experience freezing conditions. Water freezing poses a hazard to firefighters by coating equipment, roofs, ladders, and other surfaces. In addition, ice forming in and on equipment may cause it to malfunction. Pumping Apparatus Driver/Operator

  33. Pressure vs. Force • Pressure • Force per unit area • May be expressed in pounds per square foot (psf), pounds per square inch (psi), or kilopascals (kPa) • Force • A simple measure of weight • Is usually expressed in pounds or kilograms Pumping Apparatus Driver/Operator

  34. Determining Force(Customary System) • The weight of 1 cubic foot of water is approximately 62.5 pounds. • Because 1 square foot contains 144 square inches, the weight of water in a 1-square-inch column of water 1 foot high equals 62.5 pounds divided by 144 square inches 62.5 / 144 = 0.434 pounds (Continued) Pumping Apparatus Driver/Operator

  35. Determining Force(Customary System) (Continued) Pumping Apparatus Driver/Operator

  36. Determining Force (Customary System) • A 1-square-inch column of water 1 foot high exerts a pressure at its base of 0.434 psi. • The height required for a 1-square-inch column of water to produce 1 psi at its base equals 1 foot divided by 0.434 psi/ft. • Therefore, 2.304 feet of water column exerts a pressure of 1 psi at its base. Pumping Apparatus Driver/Operator

  37. Determining Force(Metric System) • A cube that is 0.1 m x 0.1 m x 0.1 m (a cubic decimeter) holds 1 liter of water. • The weight of 1 liter of water is 1 kilogram. • The cube of water holds 1 000 liters of water and weighs 1 000 kg. (Continued) Pumping Apparatus Driver/Operator

  38. Determining Force(Metric System) • Because the cubic meter of water is comprised of 100 columns of water, each 10 decimeters tall, each column exerts 10 kPa at its base. Pumping Apparatus Driver/Operator

  39. Principles of Fluid Pressure • First Principle — Fluid pressure is perpendicular to any surface on which it acts. (Continued) Pumping Apparatus Driver/Operator

  40. Principles of Fluid Pressure • Second Principle — Fluid pressure at a point in a fluid at rest is the same intensity in all directions. (Continued) Pumping Apparatus Driver/Operator

  41. Principles of Fluid Pressure • Third Principle — Pressure applied to a confined fluid from without is transmitted equally in all directions. (Continued) Pumping Apparatus Driver/Operator

  42. Principles of Fluid Pressure • Fourth Principle — The pressure of a liquid in an open vessel is proportional to its depth. (Continued) Pumping Apparatus Driver/Operator

  43. Principles of Fluid Pressure • Fifth Principle — The pressure of a liquid in an open vessel is proportional to the density of the liquid. (Continued) Pumping Apparatus Driver/Operator

  44. Principles of Fluid Pressure • Sixth Principle — The pressure of a liquid on the bottom of a vessel is independent of the shape of the vessel. Pumping Apparatus Driver/Operator

  45. Terms Associated with Pressure • Atmospheric pressure — Pressure exerted by the atmosphere at sea level (14.7 psi [101 kPa]) • psig — Pounds per square inch gauge; actual atmospheric pressure = gauge reading • psia — Pounds per square inch absolute; the psi above a perfect vacuum, absolute zero (Continued) Pumping Apparatus Driver/Operator

  46. Terms Associated with Pressure • Vacuum — Any pressure less than atmospheric pressure • Perfect vacuum — Absolute zero pressure • Negative pressure — Gauge readings of less than 0 psi or kPa Note: The term negative pressure is technically a misnomer. (Continued) Pumping Apparatus Driver/Operator

  47. Terms Associated with Pressure • Head — The height of a water supply above the discharge orifice • Head pressure — The result of dividing the number of feet that the water supply is above the discharge orifice by 2.304 • Static pressure — Stored potential energy available to force water through pipe, fittings, fire hose, and adapters (Continued) Pumping Apparatus Driver/Operator

  48. Terms Associated with Pressure • Static — At rest or without motion • Normal operating pressure — That pressure found in a water distribution system during normal consumption demands • Residual pressure — That part of the total available pressure not used to overcome friction loss or gravity while forcing water through pipe, fittings, fire hose, and adapters (Continued) Pumping Apparatus Driver/Operator

  49. Terms Associated with Pressure • Residual — A remainder or that which is left • Flow pressure (velocity pressure) — That forward velocity pressure at a discharge opening while water is flowing • Elevation — The center line of the pump or the bottom of a static water supply source above or below ground level (Continued) Pumping Apparatus Driver/Operator

  50. Terms Associated with Pressure • Altitude — The position of an object above or below sea level • Pressure loss — When a nozzle is above the pump • Pressure gain — When the nozzle is below the pump (Continued) Pumping Apparatus Driver/Operator

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