Ch 5. Principles Of Water Flashcards
Water is a compound of hydrogen and oxygen formed when:
Two hydrogen atoms combine with one oxygen atom
Ordinary freshwater weighs?
8.33 lbs
When does water exist in a liquid state?
Between 32°F and 212°F
Water may be used to smother fires in what type of combustible liquid?
Combustible liquids whose specific gravity is higher than 1
Compared to other common extinguishing agents water has?
A greater heat absorbing capacity
When water is converted to steam at 212°F, it expands it’s volume how many times?
1,700
Water is a good extinguishing agent, because it is generally both:
Inexpensive and readily available
Water has a high surface tension that makes it:
Somewhat difficult to soak into dense materials
Wetting agents may be mixed with water to help by:
Reduce its surface tension in increase its penetrating ability
Using water near energized electrical equipment is dangerous because it:
Is a good conductor of electricity
Force per unit area is a description of:
Pressure
A simple measurement of weight is?
Force
The first principle of pressure is that:
Fluid pressure is perpendicular to any surface on which it acts
The second principle of pressure is:
Pressure applied to a confined fluid is transmitted equally in all directions
The third principal of water pressure is:
Pressure applied to a confined fluid is transmitted equally in all directions
The fourth principle of pressure is:
The pressure of a liquid in an open vessel is proportional to its depth
The fifth principle of pressure is:
The pressure of a liquid in an open vessel is proportional to the density of the liquid
The sixth principle of pressure is:
The pressure of a liquid at the bottom of a vessel is independent of the shape of the vessel
What are characteristics of atmospheric pressure at high altitudes and at low altitudes?
Atmosphereic pressure is greatest at low altitudes and leastd at very high altitudes
Atmospheric pressure at sea level is?
14.7 psi
Any pressure less than atmospheric pressure in real is referred to as a?
Vacuum
The term “absolute zero pressure” refers to having a?
Perfect vacuum
The height of a water supply above the discharge orifice is defined as?
Head pressure
Stored potential energy available to force water through pipes, fittings, hose and adapters is?
Static pressure
Pressure found in a water distribution system during normal consumption demands is referred to as?
Normal operating pressure
The friction caused by water flowing through the pipes, valves and fittings is the difference between static pressure and?
Normal operating pressure
The portion of total available pressure not used to overcome friction loss or gravity well forcing water through pipes, fittings, hoses and adapters is referred to as?
Residual pressure
The forward velocity pressure while water is flowing from a discharge opening is referred to as?
Flow pressure
How is the term “elevation” described in the fire service?
The centerline of the pump or the bottom of a static water supply source above or below ground level
How is the term altitude used in the fire service?
Altitude refers to the position of an object in relation to sea level
What occurs when a nozzle is raised above the level of the pump?
Pressure loss
What occurs when a nozzle is lowered below the level of the pump?
Pressure gain
 What effect does an increase in height above sea level have on fire department pumpers?
Fire department pumpers must work increasingly harder to produce pressures required for affective fire streams
Part of the total pressure lost while forcing water through pipe, fittings, fire hose and adapters is referred to as?
Friction loss
What affect does an improper gasket size have on friction loss in a fire hose?
An improper gasket size increases friction loss
Friction loss an older hose may be as much as_____percent greater than in new hose?
50%
The first principle of friction loss is that?
If all other conditions are the same, friction loss varies directly with length of hose or pipe
The second principle of friction loss is?
Friction loss develops much faster than change in velocity
The larger the diameter of hose the ____the friction loss?
Lower
The fourth principle of friction loss is that for a given velocity, friction loss:
Is approximately the same, regardless of pressure on the water
The diameter of the hose determines the________ for a given volume of water?
Velocity
Friction loss increases as the length of hose and piping ________?
Increases
Flow pressure will always be ______near the source of supply and the ________ at the farthest point in the system?
Greatest, lowest
If velocity is increased beyond practical limits, the friction becomes so great that resistance agitates the entire system, and creates:
Critical velocity
Friction loss caused by hose length can be reduced by:
Reducing the length of the lay
When the flow of water for fire fighting needs to be increased, it is usually acceptable to use?
Larger diameter hose to reduce friction
Employing proper hose handling techniques can usually minimize friction loss caused by:
Sharp bends in the hose
Water hammer is defined as?
The sudden stopping of water moving through a hose or pipe resulting in an energy surge that is transmitted in the opposite direction
What can be done to prevent water hammer?
Slowly close nozzles, valves, and hose clamps
When a large volume of water is needed during a very large fire fighting operation, the fire department can request that the water utility department:
increase water pressure
From where is the primary water supply obtained?
From surface water or ground water
What is true about the water needs of a large city?
In cities, domestic/industrial requirements far exceed that required for fire protection
The means of moving water that uses one or more pumps that take water from the primary source and discharge it throughout the filtration in treatment process is called a?
Direct pumping system
The means of moving water that uses a primary water source located at a higher elevation than the distribution system is?
A gravity system 
The fire department main concern regarding treatment facilities is that:
Maintenance failure or other events could disable pump stations or severely hamper the purification process
A fire hydrant that receives water from only One Direction is known as a?
Dead and fire hydrant
A distribution system that provides circulating feed from several means constitutes a:
Grid system
________ are what type of water pipes (mains), with relatively widespread spacing, that convey large quantities of water to various points of the system for local distribution to smaller means of a grid system?
Primary feeders
________ consists of a network of intermediate sized pipes that reinforce the grid within various loops of the primary feeder system and aid the concentration of required fire flow at any point.
Secondary feeders
________ make up a grid arrangement of smaller means serving individual fire hydrants in blocks of consumers.
Distributors
What is the function of a valve in a water distribution system?
To provide a means for controlling the flow of water through the distribution piping
What type of valve shows whether the gate or valve seat is open, closed, or partially closed?
Indicating valves
What type of valve is commonly used on private water supply systems in which the words open or shut appear in a window as the valve approaches one position or the other?
Post indicator valve
What type of valve has a yoke on the outside with a threaded stem that controls the gates opening or closing?
Outside screw in yoke
The most common type of valves used on most public water distribution systems are:
Non-indicating valves
 What type of control valves are usually used in public water distribution systems?
Gate valves
Friction loss and water pipes can be reduced by?
Flushing hydrants periodically
Average daily consumption is defined as?
The average amount of water used per day based on the total amount of water used in a water distribution system over the period of one year
Where do most private water supply systems get their water?
Municipal water systems
With a property is served by two sources of water supply for fire protection, the municipal system and a private source consisting of non-potable water, why must the systems remain separate?
To prevent cross-contamination
What should the fire department do if there is any question about the reliability of a private water supply system or its ability to provide an adequate amount of water for a large scale fire fighting operation?
Make arrangements to augment private water supply
