Engineer notes

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  1. Characteristics of H2o
    water is a compound ( molecule ) of hydrogen and oxygen formed when two hydrogens Atoms (H2 ) combine with one oxygen atom
  2. Characteristics of H2o
    between 32°F and 212° F water exist in a liquid state
  3. Characteristics of H2o
    below 32°F is the freezing point of water
  4. Characteristics of H2o
    above 212°F is the boiling point of water
  5. Extinguishing properties of water
    the primary way water extinguishes fire is by cooling, or absorbing heat from the fire , or smothering
  6. Specific Heat
    is a measure of the heat - absorbing capacity of a substance
  7. Latent heat of vaporization
    is the quantity of heat absorbed by a substance when it changes from a liquid to a vapor

    the temperature at which a liquid absorbs enough heat to change to vapor is known as its boiling point
  8. Exposed Surface Area
    the speed with which water absorbs heat increases in proportion to the water surface exposed to the heat

    one drop of water converted to steam expands 1700 times
  9. Specific Gravity
    the density of liquids in relation to water is known as specific gravity
  10. Water Pressure and Velocity
    the weight of 1 cubic foot of water is approximately 62.5 lbs.

    A 1 inch square column of water 1 foot high exerts a pressure at its base of .434 psi.
  11. Principles of Pressure
    the speed with which a fluid travels through hose or pipe is determined by the pressure upon that fluid

    there are six basic principles that determine the action of pressure upon fluids.
  12. First Principle
    fluid pressure is perpendicular to any surface on which it acts
  13. Second Principle
    fluids press at a point in a fluid at rest is the same intensity in all diresctions
  14. Third Principle
    pressure applied to a confined fluid from withot is transmitted equally in all directions
  15. Fourth Principle
    the pressure of a liquid in an open vessel is proportional to its depth
  16. Fifth Principle
    the pressure of a liquid in an open vessel is proportional to the density of the liquid
  17. Sixth Principle
    the pressure of a liquid on the bottom of a vessel is independent of the shape of the vessel
  18. Pressure Loss and Gain
    Elevation and Altitude
    Elevation refers to the center line of the pump or the bottom of a static water supply source above or below ground level.

    Altitude is the position of an object above or below sea level .
  19. Cause for Friction Loss
    movement of water molecules against each other

    linings in the fire hose


    sharp bends in hose

    change in hose size or orifice by adapters

    improper gasket size
  20. Reducing Friction Loss
    Hose length

    Hose diameter

    Sharp bends ( kinks )
  21. Types of Pressure

    Atmospheric Pressure
    Sea level 14.7 psi.

    the atmosphere surrounding the earth has depth and density and exerts pressure upon everything on earth
  22. Head pressure
    Head in the fire service refers to the height of a water supply above the discharge orifice
  23. Static Pressure
    • potential energy
    • at rest or without motion
  24. Normal Operating Pressure
    pressure found in a water distribution system during normal demand
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Engineer notes
2013-07-13 16:09:18
Scientific Properties h2o principles

Characteristics of H2o
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