Essentials of Fire Fighting , 5 th Edition

1. Essentials of Fire Fighting, 5th Edition Chapter 12 — Water Supply Firefighter II

2. Chapter 12 Lesson Goal • After completing this lesson, the student shall be able to choose the correct water supply for various scenarios and be able to move water through a system correctly. Firefighter II

3. Specific Objectives 1. List sources of water supply. 2. Describe the three methods of moving water in a system. 3. Discuss water treatment facilities. (Continued) Firefighter II

4. Specific Objectives 4. Explain the operation of water storage and distribution systems. 5. Distinguish among the pressure measurements relevant to water supply. 6. Use a pitot tube. (Skill Sheet 12-II-1) Firefighter II

5. Surface Water Supply • Rivers • Aqueducts • Lakes • Reservoirs Firefighter II

6. Groundwater Supply • Water wells drilled into underground aquifers • Water-producing springs Firefighter II

7. Direct Pumping Systems • Most found in agriculture and industrial settings • May be tapped into by rural fire departments as needed (Continued) Firefighter II

8. Direct Pumping Systems • How they work • One or more pumps draw water from primary source, transport to point of use • If for drinking/domestic purposes, pumped into filtration and treatment facility • From there, pumped into distribution system (Continued) Firefighter II

9. Direct Pumping Systems • Disadvantages • Total dependence on pumps • Dependence on electricity to run pumps Firefighter II

10. Gravity Systems • Use primary water source located at higher elevation than distribution system, deliver water without pumps (Continued) Firefighter II

11. Gravity Systems • Gravity provides pressure to transport water • Gravity pressure adequate only when primary water source located more than 100 feet (30 m) higher than highest point in system Firefighter II

12. Combination Systems • Combination of direct pumping, gravity systems • Used in majority of communities in North America (Continued) Firefighter II

13. Combination Systems • How they work • Water pumped from treatment facility to elevated storage tanks near point of use • Water stored in tanks and delivered by gravity pressure (Continued) Firefighter II

14. Combination Systems • If storage capacity adequate relative to consumption, extended power outage/pump failure will not affect reliability/availability • Many industrial facilities have own combination water supply systems Firefighter II

15. Water Treatment Facilities • Treat water intended for domestic use to remove contaminants • Filter out particulates and add chlorine to kill bacteria, other organisms • May add fluoride to prevent tooth decay (Continued) Firefighter II

16. Water Treatment Facilities • Main concern for fire protection • Mechanical breakdown, natural disaster, etc., could disable facility’s pumps • Disabling pumping capacity would seriously reduce volume, pressure of water available • Another potential problem — Storage, use of large quantities of liquid chlorine Firefighter II

17. Water Storage and Distribution Systems • Water received from treatment facility, delivered to elevated storage tanks before being distributed • Ability of water system depends on • Capacity, elevation of storage tanks • Condition, carrying capacity of mains (Continued) Firefighter II

18. Water Storage and Distribution Systems • When water flows through pipes, movement causes friction that reduces water pressure • Friction loss reduces volume, pressure of water available from fire hydrants connected to water distribution system (Continued) Firefighter II

19. Water Storage and Distribution Systems • Types of hydrants • Dead-end hydrant • Circulating feed • Grid system • Provides circulating feed from all direction • Primary feeders • Secondary feeders (Continued) Firefighter II

20. Water Storage and Distribution Systems • Grid system • Distributors • Two or more primary feeders should run from source to high-risk, industrial districts by separate routes • Secondary feeders connect primary feeders and supply water from two directions to any point (Continued) Firefighter II

21. Water Storage and Distribution Systems • Recommended sizes of mains • Residential areas • Business, industrial areas Firefighter II

22. Water Main Valves • Provide means for controlling flow of water through distribution piping • Should be located at frequent intervals in grid system so only small sections are cut off if necessary to isolate parts of system for repairs (Continued) Firefighter II

23. Water Main Valves • Spacing should be such that only minimum length of pipe is out of service at any time • Should be operated at least once/year to keep working • Water department should be able to open valves promptly when needed (Continued) Firefighter II

24. Water Main Valves • Indicating valves • Show position of gate or valve seat • Includes most valves in fire protection systems • Post indicator valves (PIVs) • Outside stem and yoke (OS&Y) valves (Continued) Firefighter II

25. Water Main Valves • Nonindicating valves • Normally buried/installed in utility manholes • Can be operated aboveground through valve box or may need special socket wrench on end of reach rod (Continued) Firefighter II

26. Water Main Valves • Control valves • Can be indicating or nonindicating types • Gate valves • Butterfly valves (Continued) Firefighter II

27. Water Main Valves • Proper valve installation (spacing) • Necessary to close off one or two hydrants from service while single break in main is being repaired • Advantages reduced if all valves not properly maintained and kept open Firefighter II

28. Water Mains • Generally made of cast iron, ductile iron, asbestos cement, steel, PVC, plastic, or concrete • Must be proper type for soil conditions, and pressures to which will be subjected (Continued) Firefighter II

29. Water Mains • Water flow may be resisted by internal surface of pipe, encrustations, solidified sediments Firefighter II

30. Pressure • Force per unit area • Force that moves water through conduit • Measured in pounds per square inch (psi) or kilopascals (kPa) Firefighter II

31. Static Pressure • When little or no water flow, pressure that can be measured is static pressure • Rarely found in public water supply system • Defined in this context as normal pressure existing on system before water released from hydrant Firefighter II

32. Flow Pressure • Forward velocity pressure at discharge opening while water flowing • Can be measured with pitot tube and gauge Firefighter II

33. Residual Pressure • Represents pressure left in system at specific location when water flowing • That part of total available pressure not used to overcome friction/gravity while forcing water • Provides indication of availability of additional water Firefighter II

34. Summary • Because water is the primary fire extinguishing agent used by firefighters in North America, fire departments must develop ways to transport the available water from its source to where it is needed. (Continued) Firefighter II

35. Summary • Firefighters must know what water supply systems have been developed and what their responsibilities are when these systems are used. (Continued) Firefighter II

36. Summary • Firefighters must know about water sources, pumping systems, gravity systems, and the system of underground water mains used to distribute the water. Firefighter II

37. Review Questions 1. List sources of water supply for a jurisdiction. 2. What are the three methods of moving water in a system? 3. Describe the components of a grid system. (Continued) Firefighter II

38. Review Questions 4. What are static pressure, flow pressure, and residual pressure? 5. What are the two methods of holding a pitot tube properly? Firefighter II