Flashcards in Chapter 6- Water Deck (36):
What is the order from largest to smallest of water supply pipes?
2. Secondary Feeders
Is there less FL in a water distribution system when fire hydrants are supplied by one direction or two (or more) directions?
There is much less FL when a hydrant is supplied from two or more directions.
A fire hydrant that receives water from only one direction is called....
A dead-end hydrant.
When a fire hydrant receives water from two or more directions it is called...
Circulating feed or looped line.
To ensure sufficient water, how many primary feeders should run from the source of supply to the high risk industrial districts?
Two or more.
In residential areas, what is the recommended size for fire hydrant supply lines?
6 inches with 8-inch cross-connecting mains at intervals of not more than 600 feet.
What is the recommended size water mains in industrial areas?
8-inch mains with 8-inch cross-connecting mains every 600 feet.
How often should water control valves be operated to keep them in good working condition?
At least once a year
Valves for water systems are broadly divided into what two types?
Indicating and non indicating
Valves in private protection systems are generally indicating or non indicating?
Name the two types of indicating valves.
PIV-post indicator valve: Open/Shut
OS&Y-outside stem/screw and yoke: The threaded portion of the stem is out when the valve is open
The OS&Y valve is most commonly used in what application?
What two types of valves are used in water distribution systems?
Name the types of materials that can be used for underground water pipe.
Which materials should be used for added strength in underground water pipes in unstable or corrosive soils?
Reinforced concrete pipe
What two factors govern the heat absorbability of water?
Latent Heat of Vaporization
Water has the ability to extinguish fire in several ways. Name them and explain.
The primary way is cooling, or absorbing, heat from a fire.
Another way is by smothering (excluding oxygen).
When using water to smother a fire in combustible liquids, the specific gravity must be higher or lower than 1?
The specific gravity must be higher than 1. Floating liquids will not be smothered by water.
How does the exposed surface area affect water's ability to act as an extinguishing agent?
The greater the surface area of the water exposed to heat, the greater the heat absorbed.
What is the definition of Specific Heat?
The measure of the heat-absorbing capacity of a substance.
What are the two units of measurement used to measure heat transfer? Which do we use?
British Thermal Units (BTU's)
Joules 1 BTU = 1.055 kJ
We generally use BTU's.
The amount of heat required to raise the temperature of 1 pound of water 1 degree (F). [starting at 60 degrees]
Define Specific Heat.
The specific heat of any substance is the ratio between the amount of heat needed to raise the temperature of a specified quantity of a material and the amount of heat needed to raise the temperature of an identical quantity of water by the same number of degrees.
Define latent heat of vaporization.
The quantity of heat absorbed by a substance when it changes from a liquid to a vapor.
Define Boiling Point.
The temperature at which a liquid absorbs enough heat to change to a vapor.
At sea level, water begins to boil or vaporize at what temperature?
212 degrees. However, vaporization does not completely occur the moment water reaches the boiling point. Each pound of water requires about 970 BTU of additional heat to completely convert to steam.
Water expands when it converts to steam. At 212 degrees, what is this expansion?
1700 times its original volume. In hotter atmospheres, steam expands to even greater volumes.
Water is heaviest close to its freezing point and lightest close to its boiling point. Ordinary water is generally considered to weigh how much per gallon?
8.33 pounds per gallon.
Define specific gravity.
The density of liquids in relation to water.
Less than 1: lighter than water
Greater than 1: heavier than water
Liquids with a specific gravity of 1 it mixes evenly with water.
Most flammable liquids have a specific gravity of less than 1 or greater than 1?
Most flammable liquids are less than 1.
Force per unit area.
A simple measure of weight usually expressed in pounds. To understand force you must know the weight of the water and the height the column of water occupies.
What is the weight of one cubic foot of water?
Define residual pressure
The part of total available pressure not used to overcome friction loss or gravity while forcing water through pipes, fittings, hose, and adapters.
Above sea level, atmospheric pressure drops by....
0.5 psi per 1000 feet.