44 Questions
What is the weight of ordinary fresh water for fire protection purposes?
8.3 pounds per gallon
What happens to the volume of water when converted to steam at 212°F?
Occupies approximately 1,700 times its original volume
Why is water considered an excellent extinguishing agent?
It has a greater heat-absorbing capacity than other common extinguishing agents
How does the surface area of water affect its heat absorption?
More surface area results in more rapid heat absorption
What is a disadvantage of water in firefighting due to its physical property?
High surface tension making it difficult to soak into dense materials
How can water's reactivity with certain substances hinder firefighting efforts?
It may react with combustible metals and certain fuels
In what way does water's conductivity impact firefighting efforts?
It increases the risk of electrical hazards
What is force a simple measure of?
Weight
What determines the speed of a fluid traveling through a hose or pipe?
Pressure and size of the orifice
According to the 6 principles of pressure, what happens to fluid pressure at a point in fluid at rest?
It is the same intensity in all directions
What is the relationship between the pressure of a liquid in an open vessel and its depth?
The pressure is proportional to its depth
How is pressure applied to a confined fluid transmitted?
Equally in all directions
What is the standard atmospheric pressure at sea level?
14.7 psi
What is the term for any pressure less than atmospheric pressure?
Vacuum
What does 'head' refer to in the fire service?
The height of a water supply above the discharge orifice
How is head pressure in psi calculated from head in feet?
Divide the number of feet by 2.304
What is the position of an object in relation to sea level called?
Altitude
What is the term for pressure losses or gains due to gravity?
Elevation pressure
What happens to atmospheric pressure above 2000 feet in relation to firefighting pumpers?
It decreases, requiring increased effort from pumpers
What is the forward velocity pressure when water is flowing from a discharge opening?
Flow pressure
How much does atmospheric pressure fluctuate above sea level for every 1,000 feet?
Decreases 0.5 psi
What is a cause of friction loss in hoses?
Sharp bends/kinks
What does friction loss vary directly with, if all other conditions are the same?
The length of the hose or pipes
How does friction loss vary when the flow remains constant and the diameter of the hose is increased?
Friction loss decreases
For a given velocity, what happens to friction loss regardless of the pressure on water?
Friction loss is approximately the same
What determines the velocity for a given volume of water flowing through a hose?
The diameter of the hose
What is required to shape the stream of an open fire hose for firefighting purposes?
A nozzle
What are some characteristics of a hose layout that affect friction loss?
Hose length, diameter, and sharp bends or kinks
What is the purpose of partially closing master streams or hydrants before completely closing them?
To prevent water hammer
In a gravity system, where is the primary water source located in relation to the distribution system?
At a higher elevation
What type of system uses one or more pumps to take water from the primary source and discharge it through filtration and treatment processes?
Direct pumping system
What type of system most commonly utilizes both direct pumping and gravity systems with elevated tanks providing gravity flow?
Combination system
What is the term for a hydrant that receives water from only one direction?
Dead-end hydrant
What does a grid system for water distribution consist of?
Primary feeders, secondary feeders, distributors
What are the components of a grid system's primary feeders?
Large pipes with relatively wide spacing
What is the main function of a valve in a water distribution system?
Controlling the flow of water through the distribution piping
Which type of valve has a yoke on the outside with a threaded stem that controls the gate's opening or closing?
OS&Y valve
What type of valves are generally gate valves used as control valves in a public water distribution system?
Nonindicating valves
What type of valve has a hollow metal post attached to the valve housing with a threaded valve stem inside?
Post indicator valve
What is the max total amount of water that was used during any 24-hour interval within a 3 year period called?
Max daily consumption (MDC)
What restricts the interconnection of potable and nonpotable water systems?
EPA and numerous state and local water quality codes
What materials are commonly used for underground water pipes?
Cast iron, ductile iron, asbestos cement, steel, plastic, or concrete
What is the term for the maximum amount of water used in any 1-hour interval over the course of a day?
Peak hourly consumption (PHC)
What contributes to increased friction loss in underground water pipes?
Encrustation of minerals and sedimentation settling out of the water
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