Ch. 12 Water Supply

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Ch. 12 Water Supply
2011-10-16 10:55:15
Water Supply

Water Supply
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  1. Nonindicating Valves
    • Normally buried or installed in utility manholes.
    • If properly ind=stalled can be operated above ground through valve box.
    • Some cases a special socket wrench on a reach rod needed to operate.
  2. Indicating Valves
    • Visually shows positions of gate or valve.
    • Post Indicating Valve: Hollow metal post that houses valve stem. Has a plate that says open or shut.
    • Outside Stem & Yoke (OS&Y): Has a yoke on the outside with thread system that opens & invisisble when closed.
  3. What are the two types of water system valves used?
    Indicating & Nonindicating
  4. How often should valves be opened?
    At least once every year to keep them working.
  5. Why should valves be located at frequent intervals in a grid system?
    So only small sections are cut off it is necessary to locate parts of the system for repairs.
  6. American water works association recommended fire-hydrant supply mains
    • 6" diameter in resedential.
    • Closely gridded by 8" cross-connecting mains at intervals no more than 600'.
    • 12" mains on priciple streets in the long mains but cross-connecting at frequent intervals.
  7. How many primary feeders should be used for a sufficient water supply?
    • Two or more primary feeders.
    • Secondary feeders connect primary feeders & supply water from two directions to any point.
  8. Grid System Components
    • Primary Feeders: Large mains, widespread, large quantity of water.
    • Secondary Feeders: Intermediate-sized mains that run from primary to distributors.
    • Distributors: Grid of small mains serving fire hydrants & blocks of consumers.
  9. What are hydrants that receive water from more than one direction called?
    Circulating feed or looped line
  10. What is a dead-end fire hydrant?
    • A hydrant that receives water from only one direction.
    • Has a limited water supply.
  11. What does friction loss do to hydrants?
    Reduces the volume & pressure of the water flowing to the hydrant.
  12. What happens when water flows through pipe?
    The movement causes friction & reduces water pressure.
  13. A potential hazard with water treatment facility's is what?
    They typically store large amounts of chlorine.
  14. What happens if a water facility's pump goes down & there is an emergency?
    If there is a fire it could reduce the volume & pressure of water available.
  15. Gravity Systems
    • Uses water source from a higher elevation than the distribution system.
    • Pressure only adequate when source is more than 100' higher than the distribution center.
    • Ex. Alpine lakes & mountain reservoirs
  16. Direct Pumping Systems
    • Mostly found in agricultural & industrial settings.
    • One or more pumps move water from primary source to point if use.
    • Disadvantages: Total dependence on pumps & electricity