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