Ch. 1 Characteristics/Principles Of Water Flashcards
If the nozzle is at a higher elevation than the pump, the static nozzle pressure will be ______ the pressure at the pump.
Lower than
The damaging force created by quickly stopping the water that is flowing in a closed system is known as…
Water hammer
Friction loss is caused by
Kinks and bends
Movement of water in the hose
Couplings
Friction loss is reduced by using…
Larger diameter hose.
Reducing the length of hose being used.
Minimizing sharp bends or kinks.
What are the ways water can extinguish a fire?
It can cool or absorb heat from the fire, as well as smother fires. Water may also be used to smother combustible liquids whose specific gravity is higher than 1 (heavier than water). Smothering may also occur when water converts to steam within an enclosed space.
What are some advantages of using water as an extinguishing agent?
- Great at absorbing heat
- A large amount of heat is required to change water to steam, allowing more heat to be absorbed from the fire.
- The greater the surface area of water exposed, the more rapidly heat is absorbed.
- Inexpensive and readily available.
What are some disadvantages of using water as an extinguishing agent?
- High surface tension that makes it difficult to soak into dense materials.
- In cold climates, the freezing of water may create operational problems.
- Water is a conductor of electricity.
- Water is relatively heavy and can compromise a structure.
What are the different types of pressure?
Atmospheric pressure
Head pressure
Static pressure
Normal operating pressure
Residual pressure
Flow pressure
What is the first principle of friction loss?
If all other conditions are the same, friction loss varies directly with the length of the hose or pipe.
What is the second principle of friction loss?
When hoses are the same size, friction loss varies approximately with the square of the increase in the velocity of flow.
What is the third principle of friction loss?
For the same discharge, friction loss varies inversely as the fifth power of the diameter of the hose.
What is the fourth principle of friction loss?
For a given velocity, friction loss is approximately the same, regardless of the pressure on the water.
What are the various means of moving water for a system?
Direct pumping system
Gravity system
Combination system
What are the purposes of a private water supply system?
To provide water strictly for fire protection
To provide water for sanitary and fire protection
To provide water for fire protection and manufacturing
How much is ordinary fresh water considered to weigh for fire protection purposes?
1 kg/L
Water may be used to smother fires in which type of combustible liquid?
Combustible liquids whose specific gravity is higher than 1.
Compared to common extinguishing agents, water has:
a greater heat absorbing capacity.
Water has a high surface tension that makes it
somewhat difficult to soak into dense materials.
What is the most likely reason wetting agents may be mixed with water?
To reduce its surface tension and increase its penetrating ability.
What best describes the first principle of pressure?
Fluid pressure is perpendicular to any surface in which it acts.
What best describes the second principle of pressure?
Fluid pressure at a point in fluid at rest is the same intensity in all directions.
What best describes the third principle of pressure?
Pressure applied to a confined fluid is transmitted equally in all directions.
What best describes the fourth principle of pressure?
The pressure of a liquid in an open vessel is proportional to its depth.
What best describes the fifth principle of pressure?
The pressure of a liquid in an open vessel is proportionately to the density of the liquid.
What best describes the sixth principle of pressure?
The pressure of a liquid at the bottom of a vessel is independent of the shape of the vessel.
Any pressure less than atmospheric is referred to as a
vacuum
Which of the following BEST refers to the height of water above the discharge orifice?
Head pressure
Static pressure
Residual pressure
Normal operating pressure
Head Pressure
Stored potential energy available to force water through pipes, fittings, hose and adapters is…
Static pressure
What best describes the term elevation in the fire service?
The centre line of the pump or the bottom of a static water supply source above or below ground.
What best describes the term altitude in the fire service?
The position of an object in relation to sea level
What is the term that refers to the total pressure lost while forcing water through pipes, fittings, and adapters?
Friction loss
Which of the flooring is MOST likely to cause friction loss in the fire hose.
Improper gasket size
Use of newer nozzles
Mixing equipment brands
Inexperienced personnel on the hose
Improper gasket size
What best describes the first principle of friction loss
If all conditions are the same, friction loss varies directly with length of hose or pipe.
What best describes the second principle of friction loss…
This principle illustrates that friction loss develops much faster than the change in velocity.
What best describes the third principle of friction loss…
For the same discharge, friction loss varies inversely as the fifth power of the diameter of the hose.
The fourth principle of friction loss states that for a given velocity, friction loss:
is approximately the same, regardless of pressure on the water.
Does a larger diameter hose provide an advantage with friction loss
Yes. Larger diameter hose provides an advantage in less friction loss
Which of the following determines velocity for a given volume of water?
Appliances
Water source
Diameter of hose
Ambient temperature
Diameter of hose
Friction loss in a water system
increases as length of hose and pipe increases.
Employing proper hose handling techniques can usually minimize friction loss caused by
sharp bends in the hose
When a large volume of water is needed during a large incident, the fire department should
request that the water utility department increase pressure
Which would best describe where the primary water supply is obtained?
Cistern
Water tower
Water treatment facility
Surface water or ground water
Surface water or ground water
What is an accurate description about the water needs of a community?
In cities, domestic/industrial requirements far exceed that required for fire protection.
Which means of moving water uses a primary source located at a higher elevation than the distribution system?
Gravity system
Water from water storage systems in a community, such as cisterns may be…
available for fire protection
The fire department’s main concern regarding treatment facilities is that
maintenance failure or other events could disable pumping stations or severely hamper the purification process.
A fire hydrant that receives water from only one direction is known as a
dead end hydrant
This 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
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.
Which type of valve shows whether the ate or valve seat is open, closed, or partially closed?
Indicating valve
Which type of valve has a yoke on the outside with a threaded stem that controls the gate’s opening or closing?
Outside screw and yoke
Friction loss in water pipes can be reduced by
flushing hydrants periodically
When 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 they remain separate?
to prevent cross contamination
What can be stated about older fire hose in regards to friction loss…
Friction loss in older fire hoses can be 50% greater than new hoses
