Chapter 5 Charac Of Water Flashcards
Whater is a compoundof hydrogen and oxygen formed when two hydrogen combine with:
1 oxygen atom
Pg 167
Water cannot be seen in its vapor form. It only becomes visible as it rises away from the surface of the liquid and:
Begins to condense
Pg 167
For fire protection purposes ordinary fresh water is considred to weigh:
8.3 lbs / gallon
Pg 167
Water has the ability to extinguish fire by:
Absorbing heat from the fire, smother fire by excluding oxygen
It can smother fires i combustible liquids whose specific gravity is greater than 1. It may also occur when water converts to steam within a closed space
Pg 168
What characteristics make water an excellent extinguishing agent:
Great heat absorbing capacity
The greater surface area exposed the more rapidly heat is absorbed
At 212 f it converts to steam and is increased 1,7000 times its original volume
Readily avail
Pg 169
Disadvantages of water:
High surface tension
Might react with certain fuels and combustible metals like sodium and triethyl aluminum
Freezes in cold weather
Pg 169
Pressure is defined as:
Force per unit area. Pressure may be expressed as pounds per square foot, pounds per square inch or kilopascals
Pg 170
Force is defined as
A simple measure o weight and is expressed in pounds of kilograms
Pg 170
Velocity
The speed at which a fluid travels through a hose or pipe is determined by the pressure upon that fluid as well as the size of the orifice through which it is flowing.
Pg 172
First principle of pressure
Fluid pressure is perpendicular to any surface
Pg 172
Second principal of pressure
Fluid pressure when fluid is at rest is the same in all directions
Third principal of pressure
Pressure applied to a confined fluid is transmitted equally in all directions
Pg 172
Fourth principal of pressure
The pressure of a liquid in an open container is proportional to its depth. The deeper the water the more pressure at the bottom of it.
Pg 173
Fifth principal of pressure
The pressure of a liquid in an open vessel is proportional to the density of the water. The denser the liquid the more pressure it will have
Sixth principal of pressure:
The pressure of liquid at the bottom of a vessel is independent of the shape of the vessel. No matter the shape the pressure is the same
Pg 174
Pressure is greater at…… Altitudes and lower at…… Altitudes
Atmospheric pressure is
Lower altitudes pressure is greater
Higher altitudes it is lower
Atmospheric pressure it is 14.7
Pg 174
The reading of psig is?
Pounds per square inch gauge when does not include atmospheric pressure into its reading.
Pg 174/175
In the fire service head refers to:
The height of a water supply above the discharge
Pg 175
To convert head in feet to head pressure you must divide the number of feet by
2.304
Pg 175
The water flow definition of static pressure is:
Stored potential energy available to force water through pipes, fittings, hose and adapters
Pg 175
Normal operating pressure:
The pressure found in a water distribution system during normal consumption demands
Pg 176
Residual pressure
The portion of the total available pressure not used to overcome friction loss or gravity while forcing water through pipes fittings hoses or adapters
Pg 176
While water is flowing from a discharge opening the forward velocity pressure is considered
Flow pressure
Pg 176
The center line of the pump of the bottom of a static water supply source above or below ground level is:
Elevation
Pg 176
Altitude is the position of an object in relation to:
Sea level
Pg 176
The pressure losses or gains due to gravity are called:
Elevation pressure
Pg 176
Friction loss
Pressure loss due to friction
Pg 177
The friction loss in older hose may be as much as ….. Percent greater than that of new hose
50%
Pg 177
First principle of friction loss;
If all other conditions are the same, friction loss varies directly with the length of the hose or pipe
Pg 178
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 the flow
Pg 178
Third principle of friction loss:
For the same discharge, friction loss varies inversely as the fifth power of the diameter of the hose
Pg 179
When the flow remains constant, the friction loss in a hose will decrease when:
The diameter of the hose is increased
Pg 179
Fourth principle of friction loss:
For a given velocity friction loss is approx the same regardless of the pressure on the water
Pg179
Friction loss in a water system increases as the
Length of hose or piping increases
Pg180
Before water supply operations begin, the number of pumpers required to meet the requirements of the incident should be:
Determined and positioned for maximum efficiency
Pg181
There are practical limits to the velocity at which a stream can travel. critical velocity is an increase beyond this limit. It can be fixed by:
Using parallel hoselines or siamese lines to increase flow and reduce friction
Pg181
To reduce friction loss in hose length:
Reduce the length of the hose and increase the diameter
Pg 181
Sharp bends and kinks can usually be minimized by employing:
Proper hose handling techniques
Pg 181
To prevent water hammers when flowing master streams from hydrants you should partially close hydrants:
Stop the hydrant then close more as a prevention measure
Pg 181
Because the local water depts principle function is to provide potable water its officials are the experts in:
Water supply problems
Pg 182
When a large volume of water is needed the fire dept should request the water utility dept to:
Increase the water pressure in an area where there is a very large fire fighting operation
Pg 182
The primary water supply can be obtained from either:
Surface water or ground water
Pg 182
Two examples of surface water supply are:
Rivers and lakes
Pg182/183
Groundwater supply can be:
Water wells or water producing springs
Pg183
Direct pumping system uses:
One or more pumps that takes water from the primary source and discharges it through the filtration and treatment process. From there a series of pumps force the water into the distribution system
Pg 183
Gravity system:
Uses a primary water source located at a higher elevation than the distribution system. The gravity provides water pressure for the system. This is only sufficient pressure if the source is several hundered higher than the highest distribution point.
Pg183
Combination system is used by most communities and includes:
Direct and gravity systems
Pg 183
A dependable combination system involves:
Reliable duplicated equipment and proper sized strategically located storage containers
Pg184
Storage of water should be sufficient to provide:
Domestic and industrial demands plus the demands expected in fire fighting operations
Pg184
Water may be treated by:
Coagulation
Sedimentation
Filtration
Or the addition of chemicals, bacteria or other organisms
Pg184
The ability of a water system to deliver and adequate quantity of water relies upon the:
Carrying capacity of the systems network of pipes
Pg 184
When a fire hydrant receives water from two or more directions it is said to have a:
Circulating feed or a looped line
Pg184
A grid system should consist of the following components:
Primary feeders: large pipes widespread to convey large amts of water to smaller mains
Secondary feeders:
Network of intermediate sized pipes that reinforce the grid within the arious loops of the primary feeder system and aid the concentration of the required fire flow at any point
Distributors:
Grid arrangement of smaller mains serving individual fire hydrants and blocks of consumers
Pg185
The function of a valve in a water distribution system is to provide a means for:
Controlling the flow of water through the distribution piping.
Valves should be located so that only small districts are cut off if it is necessary to stop the flow at a specific point.
Pg 185/186
One of he most important factors in a water supply system is the water depts ability to promply operate:
The valves during an emergency or breakdown of equipmet
Pg 186
The two most common indicating valves are the:
Post indicator valve and the outside screw an yoke valve
Pg186
The most common type of valve used on most public water distribution systems is the:
Nonindication valves
Pg 186
Control valves in public water distribution systems are generally:
Gate valves
Pg187
If a valve resists turning after fewer than the indicated number of turns it usually means:
Debrisor other obstructions are in the valve, or it may be corroded due to lack of maintenance
Pg187
Water pipe that is used underground is generally made of:
Cast iron, ductile iron, asbestos cement, steel plastic, or concrete
Pg187
Whenever pipe is installed, it should be the:
Proper type for the soil conditions and pressures to which it will be subjected
Pg187
The adverse effects of encrustation and sedimentation (friction loss) can be reduced by:
Flushing hydrants periodically
Pg188
The water supply system average daily consumption is the:
Average amount of water used per day based on the total amount of water used in the water distribution system over the period of one year
Pg188
The water system maximum daily consumption is the:
Maximum total amount of water that was used during any 24 hr interval within a 3 year period
Pg188
The water system peak hourly consumption is the:
Maximum amount of water used in any 1 hour interval over the course of a day
Pg188
Private water supply systems are most commonly found on:
Large commercial industrial, or institutioinal properties, and may also be found in some residential developments
Pt 188
Private water supply systems exists for one of 3 purposes:
Fire protection
Sanitary
Manufacturing processes
Pg 188
