Chapter 5 Flashcards
Principles of Water
What are the states of matter?
Solid, liquid, gas
Water expands how many times or more when converted to steam?
1700
What are the advantages of water?
Water has a greater heat absorbing capacity than other common extinguishing agents
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. The amount of surface area can be increased with the use of a fog’s dream or deflection of a solid stream of an object.
At 212 degrees Fahrenheit water converted to steam occupies approximately 1700 times its original volume, helping to dissipate heat and a well-vented room. The expansion ratio is even greater at higher temperatures
Although some areas experience water shortages generally it is an inexpensive and readily available commodity
What are some disadvantages involved in the use of water as an extinguishing agent?
Water has a high surface tension that makes it somewhat difficult to soak into dense materials.
Wedding agents may be mixed with water to reduce its surface tension and increase its penetrating ability water may be reactive with certain fuels combustible metals sodium metal and triethyl aluminum. Due to low levels of opacity and reflectivity, radiant heat easily passes through water, rendering water curtains and ineffective.
In cold weather climates the 32° Fahrenheit freezing temperature of water May create operational problems such as Frozen pumps and hose lines. Safety hazards such as ice dams and slippery surfaces occur in below freezing temperatures.
Water is a good conductor of electricity. This characteristic May pose a danger to firefighters using water near energized electrical equipment
At 8.3 lb per gallon water is a relatively heavy agent. Accumulations of water within a structure can lead to an increased potential for structural collapse.
What is pressure?
Force per unit area exerted by a liquid or gas measured in pounds per square inch or kilopascals
What is force?
Simple measure of weight, usually expressed in pounds or kilograms.
What is the weight of one cubic foot of water?
62.4 pounds
How many inches does one square foot contain?
144 inches
How many principles of pressure are there?
Six principles
What PSI is atmospheric pressure at sea level?
14.7
What is a vacuum?
Any pressure less than atmospheric pressure
What is head pressure?
Alternate term for pressure especially pressure due to elevation. For every one foot increase in elevation 0.434 PSI is gained for every 1 meter increase in elevation 9.82 kPa is gained also known as head pressure
What is static pressure?
Static means at rest or without motion. If the water is not moving the pressure exerted is static.
What is residual pressure?
The pressure remaining in the water supply system while the test water is flowing
What is elevation?
Height of a point above sea level or some other reference point
What is altitude?
Geographic position of a location or object in relation to Sea level. The location may be either above below or at sea level.
What is elevation pressure?
Gain or loss of pressure and a hose line due to a change in elevation also known as elevation loss
What are the following causes of friction loss in piping?
Movement of water molecules against each other
Inside surface of piping
Pipe fittings
Valves
What are the following causes of friction loss in a fire hose?
Couplings
Sharp bends/kinks
Improper gasket size
Change in hose size or orifice by adapters
Movement of water molecules against each other
Linings of fire hose / delaminating hose
What is friction loss?
Loss of pressure created by the turbulence of water moving against the interior walls of the hose or pipe
What is a water hammer?
Force created by the rapid deceleration of water, causes of violent increase in pressure that can be powerful enough to rupture piping or damage fixtures. Generally results from closing a valve or nozzle too quickly.
What are three methods of moving water in a system?
Direct pumping system
Gravity system
Combination system
A grid system consists of the following components?
Primary feeders
Secondary feeders
Distributors
What is a grid system?
Water supply system that utilizes lateral feeders for improved distribution
What is a distribution system?
Part of an overall water supply system that receives the water from the pumping station and delivers it throughout the area to be served.
What is a post indicator valve?
Type of valve used to control underground water mains found on the supply main of installed fire protection systems. The operating stem of the valve extends above ground through a post and a visual means is provided at the top of the post for indicating open or shut
What is an outside screw and yoke valve?
A type of control valve for a sprinkler system in which the position of the center screw indicates whether the valve is open or closed.
