Chpt 4 Flashcards
The basic plan for fighting most fires depends on having an adequate supply water to confine, control, and
Extinguish the fire
Ensuring a dependable _______is a critical fire ground operation that must be accomplished as soon as possible
Water supply
At Any scene, you will obtain water from one of two means;
Pressurized systems and Static water sources
Pressurized sources may be either ______ which furnish water under pressure through fire hydrants
Municipal water systems or private water systems
Are sources such as lakes, ponds, rivers, and streams.
Static water supplies
The establishment of an adequate, continuous _____ then becomes a primary objective to support the fire attack
Water supply
Approximately _____ percent of the earths surface is covered by water .
70 to 75
The ______ allows water to flow, puddle, and remain together even after leaving the nozzle
Surface tension
As water passes through or moves by a substance, the positive and negative charges of the molecule take the various chemicals, minerals, and solvents along with it, thus earning water the title of ____
Universal solvent
Water has been used as the primary extinguishing agent in the fire service from the earliest days, mostly because of its
Wide spread availability
The amount of heat energy required to increase the temperature of a substance is known as its
Specific heat index
Waters specific heat index is
1
Water absorbs almost ____ more heat than sodium bicarbonate
5 times
Water in its liquid form weighs 8.3 pounds per gallon, adding ______ of weight to the chassis of an engine with a 750 gallon tank.
6248 pounds
Whereas its high heat absorption allows water to have notable cooling effects, water may be also converted to gas through the application of heat, an effect attributable to its high ______
Heat of vaporization
Water at ___ is almost one half pound heavier than water at 100F
32 F
The volume of water vapor is _____ times greater than that of an equal amount of liquid water; as a consequence, water displaces oxygen and effectively smothers the fire.
1700 times
The amount of particulate matter suspended in water is known as ____
Turbidity
The color of water is is directly related to the level of _____ present
Turbidity
The amount of dissolved calcium and magnesium which increases the mineral content within water, determines the waters
Level of hardness
Takes place when two dissimilar metals are immersed in water
Galvanic corrosion
Prevent or limit the flow between the two metals, thus limiting the erosion or pitting of the metals
Sacrificial anodes
Municipal water systems can draw water from wells, rivers, streams, lakes, or human made storage facilities called
Reservoirs
Municipal water systems also include a _________, where impurities from the water are removed
Water treatment facility
The distribution system delivers water from the treatment facility to the end users and fire hydrants through a complex network of underground pipes, known as
Water mains
Driver operators must understand their water distribution systems and typical operating pressures; however it is recommended that hydrant have a minimum operating pressure of
20 psi
Most ______rely on an arrangement of pumps to provide the required pressure, either directly or indirectly
Water distribution systems
Most municipal systems have multiple pumps and back up power supplies to reduce the risk of a service interruption due to a
Pump failure
In a _____, the water source, treatment plan, and storage facilities are located on Highground while the end-users live in lower lying areas, such as a community in a valley
Gravity feed system
Most municipal water supply systems use a combination of _______to deliver water.
Pumps and gravity
Large mains, known as_______, carry large quantities of water to a section of the town or city.
Primary feeders
Smaller mains, called _______, distribute the water to a smaller area.
Secondary feeders
Water mains in a well designed system will follow a _____
Grid pattern
A _______ provides water flow to a fire hydrant from two or more directions and establishes multiple paths from the source to each area.
Grid arrangement
Some water distribution systems may have ______, which supply water from one direction
Dead end mains
If two or more hydrant on the same dead end main are used to fight a fire, the upstream hydrant will have more water and water pressure than the
Downstream hydrants
Installed at intervals throughout a water distribution system allow different sections to be turned off or isolated
Control valves
Are located at the connection points where the underground mains meet the distributor pipes.
Shut off valves
If the water system in the building or to a fire hydrant is damaged, firefighters can close the _______ to prevent further water flow
Shut off valves
Refers to the force per unit area, and is measured in psi.
Water pressure
The water flow or quantity of water moving through a pipe, hose, or fittings is measured by its _____, usually in terms of gallons per minute
Volume
Water that is not moving has ____
Potential energy and kinetic energy
Fluid pressure is exerted perpendicular to any surface on which it acts
Principle 1
Pressure in fluid acts equally in all directions
Principle 2
Pressure applied to a confined fluid from without is transmitted equally in all directions
Principle 3
The pressure of a liquid in an open vessel is proportional to the depth of the liquid
Principle 4
The pressure of a liquid in an open container is proportional to the density of the liquid
Principle 5
Liquid pressure on the bottom of a container is unaffected by by the size and shape of the container
Principle 6
Is the pressure in a system when the water is not moving
Static pressure
Static pressure is ______, because it would cause the water to move if there were some place the water could go.
Potential energy
Static pressure is generally created by
Elevation pressure or pump pressure
An elevated storage tank creates _____ in water mains
Elevation pressure
For the driver operator, elevation refers to the position of the _____ as it relates to the nozzle
Pump
Atmospheric pressure decreases approximately ____ for every 1000 ft that the geographic location rises above sea level.
0.5 psi
Placing a pressure gauge on the hydrant port and opening the hydrant valve can measure _______ in a water distribution system
Static pressure
Refers to the amount of pressure in the water distribution system during a period of normal consumption
Normal operating pressure
Is the amount of pressure that remains in the system when the water is flowing
Residual pressure
When you open a hydrant and start to draw large quantities of water out of the system, some of the potential energy of the Still water is converted into the _____ of moving water.
Kinetic energy
is an important measurement because it provides the best indication of how much more water is available in the system
Residual pressure
In theory, when the maximum amount of water is flowing, the residual pressure is ____, and there is no more potential energy to push water through the system.
zero
In the fire service, _____ is considered the minimum usable residual pressure, as this level reduces the risk of damage to underground water mains or pumps.
20 psi
Is the forward pressure measured at a discharge opening while water is moving
Flow pressure
To calculate the volume of water flowing, use a _____ to measure the pressure at the center of the water stream as it passes through the opening and then factor in the size and flow characteristics of the orifice
Pitot gauge
When water is flowing through hoses, pipes, and fittings, the water is slowed by the contact it has with the walls of the hose or pipe, which resulted in
Friction loss
Is a pressure surge or wave caused by the kinetic energy of a fluid in motion when it is forced to stop or change direction suddenly
Water hammer
Are used in climates where temperatures can be expected to fall below the freezing level
Dry barrel hydrants
Are used in locations where the temperatures do not drop below the freezing mark
Wet barrel hydrants
Fire hydrants maybe place a certain distance apart, about every ____feet in residential areas and ____feet in high-value commercial and industrial areas
500 residential
300 high value
Hydrant flow testing should be conducted during the water distribution systems ______
Peak flow times
Also provide quick and reliable access to static water sources
Dry hydrants
Are often installed in lakes and rivers and close to clusters of buildings where there is a recognize need for fire protection
Dry hydrant
Dry hydrant should be flow tested at least on an annual basis and should be ______prior to use
Backed flushed
