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
That part of the total available pressure not used to overcome friction loss or gravity while forcing water through pipes, fittings, fire hose, and adapters. Remainder of what is left.
Residual Pressure
Residual pressure is identified at the location of the reading, not at the what?
flow hydrant
Forward velocity pressure at a discharge opening while water is flowing.
Flow pressure (velocity pressure)
If the size of a opening is known, a measurement of flow pressure can be used to obtain what?
Quantity of water flowing. GPM
The center line of the pump or the bottom of a static water supply source above or below ground.
Elevation
The position of a object above or below sea level.
Altitude
Pressure loss and pressure gain are refereed to as what?
Elevation pressure
Atmospheric pressure decreases approximately 0.5 psi for every ……….feet above sea level.
1000’
List six causes of friction loss in fire hose.
Movement of water molecules against each other. Lining of fire hose. Couplings. Sharp bends. Change in hose size or orifice. Improper gasket size.
The friction loss in old hose may be how much percent greater then in new hose?
50%
Commonly referred to as the “coefficient of friction”.
Inner surface of a pipe.
How many principles govern friction loss in hose or pipes?
Four
First Principle of FL: If all other conditions are the same, friction loss varies directly with the ………..of the hose or pipe.
Length.
Second principle of FL: When hoses are the same size. friction loss varies approximately with the square of the increase in the velocity of the what? (Friction loss develops much faster then the change in velocity). PAGE # 147*
Flow
Third Principle of FL: For the same discharge, friction loss varies inversely as the fifth power of the diameter of the what? Ex: 2 1/2 hose to the 5th power, compared to 3 hose to the 5th power = 98/243 = 0.4 that of the 2 1/2 hose.
hose
**Fourth Principle of FL: For a given flow velocity, friction loss is approximately the same, regardless of the ………on the water. (When the diameter of the hose doubles, the area of the hose opening increases approximately four times)
Pressure
How much pressure is required to compresses water by 1%?
30,000 psi
The smaller the hose, the greater the velocity needed to deliver the same what?
Volume
By decreasing the amount of water flowing, a firefighter reduces the speed of the water in the hose; consequently, there is less what?
Friction loss.
If velocity is increased beyond its limits, the friction loss becomes so great that the entire steam is agitated by resistance. This agitation causes a degree of turbulence called what?
Critical Velocity.
What should be done if Critical Velocity is reached>
Parallel or Siamese hose lines to increase flow and reduce friction.
Realistically, hose larger then what size can not be used for hand lines?
3”
Apparatus inlets and remote outlets should be equipped with what to prevent damage from water hammer.
Pressure relief devices.
What is used to protect high volume systems from water hammer?
Dump valves
What should FD’s ask the water utility to do when very large amounts of water are needed?
Increase the pressure.
What are the four working parts of a water system?
Source of water supply. Means of moving water. Water processing or treatment facilities. Water distribution system, including storage.
The amount of water a community needs can be determined by an engineering estimate. This estimate is the total amount of water needed for what?
Domestic and industrial use and for fire fighting use.
What is the only way that a gravity system is sufficient?
If the source is several hundred feet above the highest use point.
What type of water system do most cities use?
Combination systems
Name four ways that water may have things removed from it.
Coagulation. Sedimentation. Filtration. The Addition of Chemicals, Bacteria, or other Organisms.
The part of the water system that receives water from the pumping station and delivers it throughout the area served.
Water Distribution System
The ability of a water system to deliver an adequate quantity of water relies upon what?
The carrying capacity of the systems network of pipes.
List the three things a grid system consist of.
Primary Feeders. Secondary Feeders. Distributors.
Convey large quantities of water to various points of the system for local distribution to smaller mains.
Primary Feeders
Intermediate sized pipes that reinforce the grid. Aid the concentration of the required fire flow at any point.
Secondary Feeders
Grid arrangement of smaller mains serving individual fire hydrants and blocks of consumers.
Distributors
What should be done to ensure sufficient water to the high risk and industrial districts of the community.
Two or more primary feeders should run there on different routes.
Secondary feeders should be arranged in what?, as far as possible to give two directions of supply to any point.
loops.
Fire hydrant main size in residential areas?
6”
Residential and business area recommended cross connection main size and spacing?
8” main. No more than 600’ apart.
Size of mains used on principle streets and in long mains not cross connected at frequent intervals?
12”
Water mains as larger as what?, may be found in major cities.
48”
How often should valves be operated to keep them in good condition?
Once a year
Valves in private water systems are usually what kind?
Indicating
What type of indicating valve is most commonly used in sprinkler systems?
OS&Y
Non-indicating valves in water distribution systems are usually located in what?
Valve boxes or manholes.
What is the most common type of valve used in most public water distribution systems?
Non-indicating
What type of valves are control valves in distribution systems?
Butterfly or Gate. (Indicating or non indicating types)
What should non rising stem gate valves be marked with?
A number indicating how many turns to close the valve.
How many hydrants would have to be shut off to make a repair if the water system has the proper amount of valves installed?
One or two hydrants.
What is pipe that is used under ground typically made of?
Cast Iron. Ductile Iron. Asbestos Cement. Steel. Plastic. Concrete.
How can the effects of encrustation and sedimentation be reduced?
Flushing hydrants.
The average of the total amount of water used in a water distribution system over the period of one year.
Average Daily Consumption (ADC)
The maximum total amount of water that was used during any 24 hour interval within a 3 year period.
Maximum Daily Consumption (MDC)
The maximum amount of water used in any 1 hour interval over the course of a day.
Peak Hourly Consumption (PHC)
The maximum daily consumption is usually how many times more than the average daily consumption?
one to one and half times
The peak hourly rate normally varies from ………..the normal hourly rate.
2-4 times
Adequate water must be available at all times in the event a fire occurs. What should be strongly considered to ensure this need is meet?
The Maximum daily consumption and the Peak hourly consumption.
Most commonly found on large commercial, industrial, or institutional properties.
Private Water Supply Systems
List the three reason that a private water supply system may exist.
Strictly for fire protection. Water for sanitary and fire protection use. Water for fire protection and manufacturing use.
Most commonly private water supply systems receive there water from where?
Municipal water supply systems.
T of F Almost universally, private water supply systems maintain separate piping for fire protection and domestic/industrial services.
True
When the diameter of a hose doubles, the area of the hose opening increases by how much?
Approximately four times.
Example: it would take four 11/2” hoses to reach the same flow as one 3” hose.
