# 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

couplings

sharp bends in hose

change in hose size or orifice by adapters

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