Ch. 6: What is Water and Where Does it Come From? Flashcards
What by far, remains the most commonly used fire extinguishing agent?
water
What is water considered for all practical purposes?
incompressible
What abilities does water have to extinguish a fire?
cooling, absorbing heat from the fire; smothering, excluding oxygen
What govern the heat-absorbing ability of water?
specific heat and latent heat of vaporization
What is a measure of the heat-absorbing capacity of a substance?
specific heat
What is the amount of heat required to raise the temperature of 1 pound of water 1 degree F?
A BTU
What 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?
specific heat of any substance
Water absorbs ______ times as much heat as does an equal amount of carbon dioxide.
five
What is the quantity of heat absorbed by a substance when it changes from a liquid to a vapor?
latent heat of vaporization
What is the temperature at which a liquid absorbs enough heat to change to vapor known as?
boiling point
At its boiling point of 212 degrees F, water expands approximately how much its original volume?
1700 times
What is the tendency of a liquid to possess internal resistance to flow?
viscosity
What is the density of liquids in relation to water known as?
specific gravity
What is defined as force per unit area?
pressure
What is a simple measure of weight and is usually expressed in pounds or kilograms?
force
What is the weight of 1 cubic foot of water?
~62.5 lbs
What is the speed at which fluid travels referred to as?
velocity
What is considered standard atmospheric pressure?
At sea level, 14.7 psi
What is any pressure that is less than atmospheric pressure called?
vacuum
What is absolute zero pressure called?
a perfect vacuum
What misnomer do gauge readings of less than 0 psi or kPa often referred to in the fire service?
“negative pressure”
What is referred to the height of a water supply above the discharge orifice?
head
What is the stored potential energy available to force water through pipe, fittings, fire hose, and adapters?
static pressure
What is the pressure in a water system before water flows from a hydrant considered as?
static pressure
What is pressure found in a water distribution system during normal consumption demands?
normal operating pressure
What is that part of the total available pressure not used to overcome friction loss or gravity while forcing water through pipe, fittings, fire hose, and adapters?
residual pressure
What means a remainder or that which is left?
residual
What that forward velocity pressure at a discharge opening while water is flowing?
flow pressure
What refers to the center line of the pump or the bottom of a static water supply source above or below ground level?
elevation
What is the position of an object above or below sea level?
altitude
When a nozzle is above the pump,
there is pressure loss.
When the nozzle is below the pump,
there is pressure gain.
What is referred to as elevation pressure?
pressure loss and gain
What is the common term for pressure loss due to friction?
friction loss
What is that part of total pressure lost while forcing water through pipe, fittings, fire hose, and adapters?
friction loss
What is referred to as suddenly stopping water moving through a hose or pipe results in an energy surge being transmitted in the opposite direction?
water hammer
What can be obtained from either surface water or groundwater?
primary water supply
What system use one or more pumps that take water from the primary source and discharge it through the filtration and treatment processes?
direct pumping systems
What system uses a primary water source located at a higher elevation than the distribution system?
a gravity system
What is a fire hydrant that receives water from only one direction known as?
a dead-end hydrant
What is known as a hydrant that receives water from two or more directions ?
circulating feed or a looped line
What is a distribution system that provides circulating feed from several mains constitute?
a grid system
What are large pipes (mains), with relatively widespread spacing, that convey large quantities of water to various points of the system for local distribution to the smaller mains?
primary feeders
What are network of intermediate-sized pipes that reinforce the grid within the various loops of the primary feeder system and aid the concentration of the required fire flow at any point?
secondary feeders
What are grid arrangement of smaller mains serving individual fire hydrants and blocks of consumers?
distributors
What is the recommended size for fire hydrant supply mains in residential areas?
at least 6 inches
What is the minimum recommended size of a main in the business and industrial districts?
8 inch main
What size mains may be used on principal streets and in long mains not cross-connected at frequent intervals?
12 inch mains
What are two common indicator valves?
PIV and OS&Y
What valve has a yoke on the outside with a threaded stem that controls the gate’s opening or closing?
OS&Y valve
What valve is the most commonly used on sprinkler systems?
OS&Y
What are the most common types of valves used on most public water distribution systems?
nonindicating valves
What is the average of the total amount of water used in a water distribution system over the period of one year?
average daily consumption (ADC)