Chapter # 6 What is Water and Where does it come From? Flashcards
Water is considered to be incompressible, and its weight varies at what?
Different Temps
Waters weight per unit of volume.
Water Density
What is the weight of water in its three forms of matter?
Close to frozen = 62.4 lbs per cubic foot
Close to boiling = 60 lbs per cubic foot
Ordinary fresh water = 62.5 lbs per cubic foot.
What is the weight of one gallon of water?
8.33 lbs
Water can be used to smother combustible fuel fires, that involves combustible fuels who’s specific gravity is what?
Higher then 1
As a extinguishing agent what four things does water depend on?
Specific Heat. Latent Heat of Vaporization. Exposed Surface Area. Specific Gravity.
A measure of heat absorbing capacity of a substance.
Specific Heat
Amounts of heat transfer can be measure in these two ways.
BTU’s and Joules
The amount of heat required to raise the temp of 1 lbs of water 1 degree.
BTU
The joule is a measure of work that has replaced what in the SI?
The calorie
T or F The specific heat of any substance is the ratio between the amount of heat needed to raise the temp of a specific quantity of a material and the amount of heat needed to raise the temp of a identical quantity of water by the same number of degrees.
True
The quantity of heat absorbed by a substance when it changes from a liquid to a vapor.
Latent Heat of Vaporization
How many more BTU’s does it require to turn water into steam after it reaches its boiling point?
970 BTU’s
How many BTU’s does it take to get 1 gallon of water to 212 F? How many BTU’s does it take to get 1 gallon of water to turn to steam?
1,266 BTU’s. 9,346 BTU’s.
The rate at which a object gives off heat depends on these three factors.
Physical form. Amount of surface area exposed. Air or Oxygen Supply.
The speed at which water absorbs heat increases in proportion to what?
The water surface exposed to heat.
At 212 F how many times its original volume does water expand?
1700 times
Name three observable results that a water fire stream is being effective in a room.
Fire is extinguished or reduced in size. Visibility maintained. Room temp reduced.
The tendency of a liquid to possess internal resistance to flow.
Viscosity
The density of a liquid in relation to water.
Specific Gravity
If a specific liquid other then water, has a specific gravity of 1 what will happen?
It mixes evenly with water.
What is the specific gravity of most flammable liquids?
Less then 1.
What are some disadvantages of using water as a extinguishing agent?
High surface tension that makes it hard to penetrate dense materials. May be reactive with certain fuels such as some metals. Low level of opacity and reflectivity which allows radiant heat to pass through it. Water freezes. Readily conducts electricity.
Force per unit area.
Pressure
A measure of weight as it is related to the force of gravity.
Force
***A 1 square inch column of water that is 1 foot height exerts how much pressure at the base?
0.434
***How many feet of a square 1” column of water is needed to equal 1 psi at the base?
2.304
The speed at which a fluid travels through a hose or pipe is determined by the pressure upon that fluid. The speed that the fluid travels is called what?
Velocity
There are ……… principles that determine the action of pressure upon fluids.
six
First principle: Fluid pressure is ……….to any surface on which it acts.
Perpendicular
Second principle: Fluid pressure at a point in a fluid at rest is the same intensity in all ……….
Directions
Third Principle: Pressure applied to a confined fluid from without is transmitted equally in ……… This is only true if there is no change in elevation of the container (stand pipe).
all directions.
Fourth Principle: The pressure of a liquid in a open vessel is proportional to its……….
Depth.
Fifth Principle: The pressure of a liquid in an open vessel is proportional to the …………of the liquid.
Density (water vs mercury)
Sixth Principle: The pressure of a liquid on the bottom of a vessel is independent of the …………..of the vessel.
Shape
What is considered standard atmospheric pressure?
14.7 psi
What does PSIG stand for?
Pounds per square inch gauge.
Any pressure less then atmospheric pressure is called what? Absolute zero pressure is called what?
Vacuum. Perfect Vacuum.
The height of a water supply above the discharge orifice.
Head
To convert head in feet to head in pressure, divide the number of feet by what?
2.304
Stored potential energy available to force water through pipes, fittings, fire hose, and adapters. At rest with no motion.
Static
Pressure found in a water distribution system during normal consumption demands.
Normal Operating Pressure