IFSTA Chapter 5 Principles Of Water Flashcards
Actual weight of Fresh Water
Ft cubed and lbs per gallon
62.4 lbs/ft cubed or 8.3 lbs per gallon
How Does water extinguish fire and how does it work for flammable liquids
Cooling, absorbing heat, and smother
Water can also smother fires in combustible liquids whose Specific Gravity is higher than 1
How does a wetting agent (foam) aid water
Reducing its surface tension and increasing the penetrability of water.
Atmospheric Pressure at sea level
14.7 psi
Any Pressure less than atmospheric pressure is called?
Vacuum
How to convert head pressure from height to PSI…
Must divide the total height by 2.304
How is Residual Pressure defined by IFSTA
Total available pressure not used to overcome friction loss or gravity while forcing water through pipes
Friction Loss in older hose vs newer hose may be…
Much greater due to newer hose having a smoother inner lining
The same volume of water supplied into a fire hose under pressure at one end….
Will be discharged at the other end
The Diameter of the hose determines _______ for a given volume of ______
The Velocity for a given volume of water
What causes agitation and is known as critical velocity
A degree of turbulence caused by increasing water velocity beyond its limit of travel.
“Certain hoses at set distances become undesirable due to reduction of flow”
Three main type of water systems and their means of moving water
Direct Pumping System: uses one or more pumps to move water from one end to the other
Gravity System: Uses a water source located higher than the distribution center
Combination Systems: Systems that use both gravity and pumps to supply water through their pipes
A Fire hydrant receiving water from only one direction is known as
Dead - End hydrant
Fire hydrant receiving water from two or more directions is known to have a
Circulating feed or looped line
Two common Building Systems Indicator Valves
Two common valves are Outside Screw & Yolk and Post Indicator Valve
