What Is Water And Where Does It Come From Flashcards
Two ways water extinguishes fire..
Cooling / absorbing heat (primary)
Smothering
Specific heat def.
A measure of the heat-absorbing capacity of a substance
BTU
British thermal unit
Amount of heat required to raise the temp of one pound of water 1 degree F
(Starting at 60 degrees)
Latent heat of vaporization def
Heat absorbed by a substance when it changes from a liquid to a vapor
Additional amount of energy required to convert liquid to steam
970 BTUs
Exposed surface area relevance
The speed that water absorbs heat increase in proportion to water surface exposed to heat
Water to steam expansion ratio
1:1,700
Specific gravity def
Density of a liquid in relation to water
Les than 1 float on water
Greater than 1 sink in water
Most flammable liquids are less than 1
1st principle of pressure
Fluid pressure is perpendicular. To any force on which it acts.
Second principle of fluid pressure.
Fluid pressure at rest is the same in all directions
Or there is no pressure in all directions
Used in hydrostatic testing.
Third principle or fluid pressure
Confined pressure is transmitted equally in all directions
Fourth principle of fluid pressure
Pressure of fluid in an open vessel is proportioned to its depth.
Fifth principle of fluid pressure
Fluid pressure in a open vessel is proportionate to is density
Sixth principle of fluid pressure
Pressure at the bottom of a vessel is independent of the shape of that vessel.
Head pressure def
Height of the water supply above the Discharge orifice.
Static pressure def
Stores potential energy available to force water though pipes hoses and nozzles
Normal operating pressure
Pressure found in a water distribution system during normal consumption demands.
Residual pressure def
Part of the pressure that is left after friction loss is taken into account.
Flow pressure
Forward velocity at the discharge opening
Elevation vs. altitude.
Fire terms
Elevation - measures from the center line of the pump or the bottom of a static water source
Altitude - above or below sea level
Friction loss due to old hose vs. new
Up to %50 greater
1st Principle of friction loss
Varies directly with length of hose
2nd principle of friction loss
Friction loss varies with the squares of the increase in velocity.
If increased from 200 - 400. 2 squared
Or 200 - 600. 3 squared
Third principle of friction loss
FL varies inverse to the 5th power with increasing hose diameter.
2.5 to the fifth over 3 to the fifth.
Fourth principle of friction loss
At a given flow velocity friction loss is approximately the same regardless of the pressure on the water.
Water distribution system function
Receives water from pumping station and delivers it throughout the area served.
Dead end hydrant
Revives water from only one direction.
Circulating feed or looped line
Hydrant that receives water through more than on direction
Grid system
Distribution system that provides circulating feeds from several mains.
Primary feeders
Large pipes (mains) with widespread spacing conveying large quantities of water
Secondary feeders
Network of intermediate sized pipes that reinforce the Grid and aid the concentration of the required fire flow
Distributors
Smaller main serving individual hydrants and blocks of consumers
Minimum diameter for hydrant supply mains in residential area
6 in
With 8in mains every 600 ft
High risk industrial districts
Two or more primary feeders should run from source.
Minimum 8in main recommended
Valves operates how often?
Min once a year
PIV valve
Post indicator valve.
Hollow metal post with words open and shut.
OS&Y Valve
Outside stem and yoke
When stem is outside valve is open.
Non indicating valve
Most often in a man hole.
Most common type of valve.
ADC
Average daily consumption
Average calculated over one year
MDC
Maximum daily consumption
Max used in one day over a three year period.
PHC
Peak hourly consumption
Max in a one hour interval over one day
Private water system are usually installed for 3 reasons
Fire protection
Sanitary
Manufacturing
Can always be used for fire.
How much a cubic foot of water weigh?
62.5 lbs
Four fundamental components of water system.
Source
Means of moving water
Treatment facilities.
Distribution systems
