Ch. 5 - Principles of Water Flashcards
Water cannot be seen in its _______ form. It only becomes visible as it rises away from the surface of the liquid and begins to ___________.
vapor / condense
p 167
Water is considered to be virtually _____________, and it’s ________ varies at different temperatures.
incompressible / weight
p 167
Waters density, or its weight per unit of volume, is measured in ?
pounds per cubic foot
p 167
For fire protection purposes, ordinary fresh water is considered to weight ______ lb/ft^3 or _____ lb/gal.
62.4 lb/ft^3 / 8.3 lb/gal
p 167
Water has the ability to extinguish fire in several ways. It can ______ or _______ heat from the fire, as well as __________ fires.
cool or absorb / smother (exclude oxygen from)
p 168
Water may also be used to smother fires in combustible liquids whose specific gravity is ?
higher than 1 (heavier than water)
p 168
Advantages of water:
- Water has a greater _____-__________ capacity than other common extinguishing agents.
- A large amount of heat is required to change water to steam, allowing more ?
- Although some areas experience water shortages, generally it is an ___________ and _______ available commodity.
- heat-absorbing
- heat to be absorbed from the fire
- inexpensive and readily
p 169
Advantages of water:
- The greater the _________ ______ of water exposed, the more rapidly heat is absorbed. The amount of _________ ______ can be increased with the use of a _____ stream or deflection of a _______ stream off an object.
- At 212F (100C), water converted to steam occupies approximately ______ times its original volume, helping to dissipate heat in a well-vented room. The expansion ratio is even greater at ?
- surface area / surface area / fog / solid
- 1700 times / higher temperatures
p 169
Disadvantages of water:
- Water has a high surface tension that makes it somewhat difficult to soak into ________ __________.
- Water may be reactive with certain fuels, ___________ metals, _________ metal, and ___________ aluminum. Due to low levels of ________ and _____________, radiant heat easily passes through water.
- dense materials
- combustible metals, sodium metal, and triethyl aluminum / opacity and reflectivity
p 169
Disadvantages of water:
- In cold weather climates, the 32F (0C) freezing temperature of water may created operational problems such as ?
- Water is a good conductor of ____________.
- At _____ pounds per gallon, water is a relatively ________ _______.
- frozen pumps and hoselines
- electricity
- 8.3 / heavy agent
p 169-170
______ ______ remains the most common weapon in the firefighters arsenal.
plain water
p 167
- Force per unit area exerted by a liquid or gas measured in pounds per square inch (psi) or kilopasclas (kPa).
Pressure
p 170
Simply measure of weight, usually expressed in pounds or kilograms.
Force
p 170
Principles of Pressure:
The speed at which a fluid travels through a hose or pipe is determined by the __________ upon that fluid as well as the size of the _______ through which it is flowing. This speed is often called __________.
pressure / orifice / velocity
p 172
Principles of Pressure:
First Principle
Fluid pressure is ______________ to any surface on which it acts. The first principle is illustrated by a vessel having _____ sides and containing water.
perpendicular / flat
p 172
Principles of Pressure:
Second Principle
Fluid pressure at a point in fluid at rest is the same __________ in all directions. This principle is used in ____________ testing.
intensity / hydrostatic
p 172
Principles of Pressure:
Third Principle
Pressure applied to a confined fluid is transmitted _________ in all directions. For example, if a pumper is connected to a closed standpipe 100 feet tall and 100 psi is applied to the standpipe, a gauge at the top of the standpipe would read _____ psi. However a gauge at the bottom of the standpipe would read 143.4 psi because of the _________ of the water in the standpipe.
equally / 100 psi / weight
p 172-173
Due to the increase in water pressure requirements necessary for the height of the building, __________-__________ devices are installed in standpipe systems that serve high-rise buildings. These devices allow hoselines to be more easily ___________, while allowing the high pressures required to access upper floors.
pressure-regulating / controlled
p 173
Principles of Water:
Fourth Principle
The pressure of a liquid in an open vessel is proportional to its ________.
depth
p 173
Principles of Water:
Fourth Principle
The depth of water is 1 foot in the first container, 2 feet in the second, and 3 feet in the third. The pressure at the bottom of the second container is ________ that of the first, and the pressure at the bottom of the third container is ________ times that of the first.
twice / three
p 173
Principles of water:
Fifth Principle
The pressure of a liquid in an open vessel is proportional to the _________ of the liquid.
density
p 173
One inch of mercury creates the same pressure at the bottom of a container as 13.55 inches of water. Thus mercury is 13.55 times _________ than water.
denser
p 173
Principles of water:
Sixth principle
The pressure of a liquid at the bottom of a vessel is independent of the ?
shape of the vessel
p 174
The ____________ pressure that surrounds the earth has depth and destiny, exerting pressure on everything.
atmospheric
p 174
Atmospheric pressure is greatest at _____ altitudes and least at very _____ altitudes.
low / high
p 174
Atmospheric pressure at sea level is _____ psi, which is considered standard atmospheric pressure.
14.7 psi
p 174
A common method of measuring atmospheric pressure is by comparing the weight of the atmosphere with the weight of ___________.
mercury
p 174
When observed in a vertical cylinder, the greater the atmospheric pressure, the _________ the column of mercury.
taller
p 174
A pressure of 1 psi makes the column of mercury about ______ inches.
2.04 inches
p 174
At _____ level, the column of mercury is 2.04 x 14.7 or 29.9 inches tall.
sea
p 174
What does psig stand for?
pounds per square inch gauge
p 174
What does psia stand for?
pounds per square inch absolute
p 174
- In the fire and emergency services, a pressure that is somewhat less than atmospheric pressure; a __________ is needed to facilitate drafting of water from a static source.
Vacuum / vacuum
p 175
In the fire service, ______ refers to the height of a water supply above the discharge orifice.
head
p 175
- Alternative term for pressure, especially due to elevation. For every 1-foot increase in elevation, 0.434 psi is gained.
Head
p 175
The water flow definition of _______ pressure is stored potential energy available to force water through pipes, fittings, hose, and adapters.
static
p 175
_______ means at rest, or without motion.
Static
p 175
Water pressure may be produced by an __________ water supply, _____________ pressure, or a _______.
elevated / atmospheric / pump
p 175
If water is not moving, the pressure exerted is ________.
static
p 175
The pressure in a system before it flows from a hydrant is considered ________ for fire service purposes.
static
p 175
The pressure found in a water distribution system during normal consumption demands is considered the ?
normal operating pressure
p 176
- Pressure at the test hydrant while water is flowing; represents the pressure remaining in the water supply system while test water is flowing and is that part of the total pressure that is not used to overcome friction or gravity while forcing water through fire hose, pipe, fittings, and adapters.
Residual Pressure
p 176
___________ pressure is the portion of the total available pressure not used to overcome friction loss or gravity while forcing water through pipes, fittings, hoses or adapters. ___________ is the remainder of that which is left.
Residual pressure / residual
p 175
While water is flowing from a discharge opening, the forward velocity pressure is considered _______ __________.
flow pressure
p 176
Use a _______ tube and _______ to measure the forward velocity of flow pressure.
Pitot tube / gauge
p 176
When measuring the forward velocity of flow pressure using a nozzle; a _________ ______ nozzle must be used with the pitot tube and gauge.
smooth bore
p 176
- Height of a point above sea level or some other reference point.
Elevation
p 176
- Geographic position of a location or object in relation to sea level. The location may be either above, below, or at sea level.
Altitude
p 176
- Gain or loss of pressure in a hoseline due to a change in elevation.
Elevation Pressure (also know as Elevation Loss)
p 176
When a nozzle is above the level of the pump, there is pressure ______. Conversely, when a nozzle is below the pump, there is pressure ______.
loss / gain
p 176
At altitudes above 2000 feet, the lessening of atmospheric pressure means fire department pumpers must work?
increasingly harder to produce the pressures required for effective fire streams.
p 176
True or False:
Less dense atmospheric pressure reduces a pumpers effective lift when drafting?
True
p 176
Above sea level, atmospheric pressure decreases approximately _____ psi for every 1000 feet.
0.5 psi
p 176
- Loss of pressure created by the turbulence of water moving against the interior walls of the hose or pipe.
Friction Loss
p 177
The fire service definition of ________ _____ is that part of the total pressure lost while forcing water through pipe, fittings, fire hose, and adapters.
friction loss
p 177
The friction loss in older hose may be as much as _____ percent greater than that of new hose.
50 percent
p 177
The rougher the inner surface of the pipe (commonly referred to as the coefficient of friction), the greater the ?
friction loss will be
p 177
Friction loss:
A common fire service example compares the difference in pressure between a _________ and ________.
nozzle and pumper
p 178
Principles of friction loss:
First principle
If all other conditions are the same, friction loss varies directly with the _______ of the hose or pipe.
length
p 178
Principles of friction loss:
Second principle
When hoses are the same size, friction loss varies approximately with the square increase in the ?
velocity of the flow
p 178
A length of 3 inch hose is flowing 200 gpm has friction loss of 3.2 psi. As the flow doubles from 200 to 400 gpm the friction loss increases ?
four times (2^2 = 4) 3.2 X 4 = 12.8 psi friction loss
p 178
Principles of friction loss:
Third principle
For the same discharge, friction loss varies inversely as the fifth power of the ?
diameter of the hose
p 179
When the flow remains constant, the friction loss in a hose will decrease when the diameter of the hose is __________.
increased
p 179
Principles of friction loss:
Fourth principle
For a given _________, friction loss is approximately the same, regardless of the pressure on the water.
velocity
p 179
With water being virtually incompressible, a pressure of _______ psi is required to reduce its volume one percent.
30,000 psi
p 179
The diameter of the hose determines the _______ for a give volume of water.
velocity
p 179
Friction loss in a water system increases as the length of _______ or ________ increases.
hose or pipe
p 180
Flow pressure will always be greatest near the ________ of ________ and lowest at the _________ _______ in the system.
source of supply / farthest point
p 180
- Force created by the rapid deceleration of water; causes a violent increase in pressure that can be powerful enough to rupture piping or damage fixtures. Generally results from closing a valve or nozzle too quickly.
Water Hammer
p 181
The primary water supply can be obtained from either ________ water or ________ water.
surface / ground
p 182
True or False:
In cities, the domestic / industrial requirements far exceed that required for fire protection?
True
p 183
Two examples of surface water are ?
rivers and lakes
p 182-183
Groundwater supply can be ?
water wells or water-producing springs
p 183
There are three methods of moving water in a system:
- __________ ____________ system
- __________ system
- ______________ system
- Direct pumping
- Gravity
- Combination
p 183
- Part of an overall water supply system that receives the water from the pumping station and delivers it throughout the area to be served.
Distribution System
p 184
A fire hydrant that receives water from only one direction is known as a ?
Dead end hydrant
p 184
When a fire hydrant receives water from two or more directions, it is said to have ?
circulating feed or a looped line
p 184
- Water supply system that utilizes lateral feeders for improved distribution
Grid System
p 184
Valves in private fire protection systems are usually of the ____________ type.
indicating type
p 186
Two common indicator valves are ?
post indicator valve (PIV) and the outside screw and (OS&Y) valve
p 186
_______________ valves are the most common type of valves used on most public water distribution systems.
Nonindicating valves
p 186
Control valves in public water distribution systems are generally _______ valves.
gate valves
p 187
Nonrising-stem gate valves should be marked with a number indicating the number of ?
turns necessary to completely close the valve
p 187
Water System Capacity:
Three basic rates of consumption
* The __________ ________ ____________ is 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.
* The ____________ ________ ____________ is the maximum total amount of water that was used during any 24-hour interval within a 3 year period.
* The _______ _________ ______________ is the maximum amount of water used in any 1 hour interval over the course of a day.
- average daily consumption (ADC)
- maximum daily consumption (MDC)
- peak hourly consumption (PHC)
p 188
Interconnecting ___________ and ___________ water systems is restricted by the Environmental Protection Agency and numerous state and local water quality codes.
potable and nonpotable
p 189
The term pressure may have a variety of meanings. In this manual, pressure is defined as?
force per unit area
p 170
Pressure is easily confused with _______. ________ is a simple measure of weight and is expressed in pounds or kilograms.
force / force
p 170
Force:
Stacking water containers increases the pressure per?
square foot
p 171
Mercury has a specific gravity greater than, as it will ______ in water.
sink
p 173
Sixth principle of pressure:
This principle is illustrated by observing water in serval different shaped containers, each having the same cross-sectional area at the bottom and the same height. The pressure is the ?
same in each container
p 174
Any pressure less than atmospheric pressure is called _________, and absolute zero pressure is called a __________ __________.
vacuum / perfect vacuum
p 175
The height of the water supply above the fire hydrant creates the _______ pressure.
head
p 175
True ________ pressure is seldom found in municipal water systems because there is always some flow in the pipes due to normal use.
static
p 175
The pressure in a system before it flows from a hydrant is considered _______ for fire service purposes.
static
p 175
The difference between static pressure and normal operating pressure is the __________ caused by water flowing through the pipes, valves, and fittings of the system.
friction
p 176
___________ refers to the center line of the pump or the bottom of a static water supply source above or below ground level.
Elevation
p 176
___________ is the position of an object in relation to sea level.
Altitude
p 176
The pressure losses or gains due to gravity are called ?
elevation pressure
p 176
The following causes friction loss in a fire hose:
- Movement of water ___________ against each other
- __________ of fire hose / delaminating hose
- __________
- Sharp ______ / ______
- Change in hose _______ or _________ by adapters
- Improper _________ size
- molecules
- Linings
- Couplings
- bends / kinks
- size or orifice
- gasket
p 177
The _________ the inner surface of the pipe the greater the friction loss will be.
rougher
p 177
The difference in the ___________ pressure between two gauges placed a distance apart in the same diameter hose or pipe when water is flowing is the friction loss for that distance.
residual
p 177-178
The second principle of friction loss illustrates that friction loss develops much faster than the change in __________.
velocity
p 178
When the flow remains constant, the friction loss in a hose will decrease when the diameter of the hose is __________.
increased
p 179
The smaller the hose, the greater the __________ needed to deliver the same volume.
velocity
p 179
Reducing friction loss:
* Hose length - To reduce friction loss caused by hose length or diameter, reduce the length of the _____ and increase the __________ of the hose.
lay / diameter
p 181
True or False:
In cities, the domestic / industrial requirements for water far exceed that required for fire protection.
True
p 183
Means of moving water:
- ________ ____________ system - uses one or more pumps that takes water from the primary source and discharges it through the filtration and treatment processes.
Direct pumping system
p 183
Means of moving water:
- __________ system - Uses a primary water source located at a higher elevation than the distribution system.
Gravity system
p 183
Means of moving water:
- _______________ system - Most communities use a combination of the direct pumping and gravity systems
Combination system
p 183
The storage of water in __________ reservoirs can also ensure water supply when the system becomes otherwise inoperative.
elevated
p 184
There is much less pressure loss in a water distribution system when fire hydrants are supplied from ?
two or more directions
p 184
Grid system:
- ___________ __________ - Large pipes (mains), with relatively widespread spacing, that convey large quantities of water to various points of the system for local distribution to the smaller mains.
Primary feeders
p 184
Grid systems:
- ___________ ________ - Network of intermediate sized pipes that reinforce the grid within the various loops of the primary feeder system and aid the concentration of the required fire flow at any point
Secondary feeders
p 185
Grid systems:
- ______________ - Grid arrangements of smaller mains serving individual fire hydrants and blocks of consumers
Distributors
p 185
An _____________ valve visually shows whether the gate or valve seat is open, closed or partially closed.
indicating valve
p 186
The adverse effects of encrustation and sedimentation in water pipes can be reduced by ?
flushing hydrants periodically
p 188
___________ water supplies are most commonly found on large commercial, industrial, or institutional properties but may also be found in some residential developments.
Private
p 188
Most commonly, private water supply systems receive their water from a ___________ water supply system.
municipal
p 188
Almost universally, private water supply systems maintain separate piping for ?
fire protection and domestic / industrial services
(distinct contrast to most municipal water supply systems in which fire hydrants are connected to the same mains that supply domestic / industrial use )
p 189
