Flashcards in Chapter 6 What is Water and Where Does It Come From Deck (60)
Water is a compound of hydrogen and oxygen formed when:
two hydrogen atoms combine with one oxygen atom.
Water exists in a liquid state between:
32ºF and 212ºF (0ºC and 100ºC)
Water converts to a solid state (ice) below:
Water converts to steam above:
Water is lightest close to its boiling point – weighing approximately:
60 lb/ft3 (0.96 kg/L).
For fire protection purposes, ordinary fresh water is generally considered to weigh:
8.33 lb/gal (1kg/L)
What is specific heat?
A measure of the heat-absorbing capacity of a substance
What unit is used to measure amounts of heat transfer?
British thermal unit (Btu) or joule (J)
What is a Btu?
The heat required to raise the temperature of 1 pound of water 1ºF
What unit of measurement has the joule taken the place of in the SI (International System of Units)?
The latent heat of vaporization is:
The quantity of heat absorbed by a substance when it changes from a liquid to a vapor
What is the name for the temperature at which a liquid absorbs enough heat to change to a vapor?
Vaporization does not completely occur at boiling point. Each pound of water requires approximately ___ Btu (kJ) of additional heat to completely convert into steam.
970 Btu (1 023 kJ)
Approximately how much does water expand beyond its original volume when converted to steam at 212ºF (100ºC)?
The speed with which water absorbs heat increases in proportion to:
the water surface exposed to the heat.
Steam expansion is ___ inside a burning building.
What is specific gravity?
The density of liquids in relation to water
What kinds of liquids are lighter than water and therefore float on water?
Those with a specific gravity less than 1
What kinds of liquids are heavier than water and sink to the bottom?
Those with a specific gravity greater than 1
Most flammable liquids have a specific gravity of:
less than 1
How much pressure is required to reduce the volume of water one percent?
30,000 psi (210 000 kPa)
Friction loss in a system ___ as the length of hose or piping ___.
Flow pressure will always be ___ near the supply source and ___ at the farthest point in the system.
If an opening is made directly at the hydrant, as opposed to the nozzle, the flow will be much ___ at a ___ pressure.
If velocity is increased beyond practical limits, the friction becomes so great that resistance agitates the entire stream, creating:
What is water hammer?
The sudden stopping of water moving through a hose or pipe resulting in an energy surge being transmitted in the opposite direction, often at many times the original pressure
Close nozzles, hydrants, valves, and hose clamps ___ to prevent water hammer.
Equip apparatus inlets and remote outlets with ___ to prevent damage to equipment.
pressure relief devices
High-volume systems should be protected with: