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Household Water

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					Household Water
          By:
     Zoila Quiroz
           &
    Diana Chavez
              Overview
 Terms
 Pascals Principle
 Water Pressure
 Water Tower, Pumps
 How we get water into our home
 Pipes
 Experiment
 Closing
                         Terms:
   Pressure: defined by the equation
    Pressure = Force / Area
   Units
   The units of pressure are those of force divided by the
    units of area. The exact units depend on which system
    you are using

   In scientific units force is measured in Netwons (1 N = 1
    kg m / s2) and area in m2. Pressure has units of N/m2
   In Imperial units force is measured in pounds and area in
    in2. Pressure has units of lbs/in2 (psi for short)
                       More Terms:

   Atmospheric Pressure: Atmospheric pressure is the pressure
    exerted at the surface of a body by a column of air in an
    atmosphere. The pressure varies both with altitude, and weather
    patterns. Standard is an average atmospheric pressure at sea level,
    and is defined as 1 atmosphere on Earth, equal to 760 millimeters of
   mercury (760 Torr) and 101,325 Pascals.
1 atmosphere = 14.7 lbs/in2 = 101,000 N/m2 = 1.01325 bars = 760 Torr
   = 32 feet of water
True Pressure: The total pressure exerted on a system equal to the
   gauge pressure and atmospheric pressure.
Gauge Pressure: The pressure of a system measured by the gauge
   which excludes atmospheric pressure
               Pascal’s Principle
Pascal’s Principle: When a pressure is
 applied to a confined liquid, that a
 pressure is transmitted throughout the
 extent of the liquid.
   Pressure exerted on an enclosed liquid is transmitted
    equally to every part of the liquid and to the walls of the
    container. (Pascal's principle)
   A manometer relies on Pascal's principle to measure
    pressure in gases.
   Pascal's principle is important in understanding
    hydraulics, the study of the transfer of forces through
    fluids.
                     Water Pressure

 Water Pressure Explained
 As we turn on the kitchen faucet or start a bath, how the water is coming
  out may not be something we think about. (Unless of course it is dripping or
  not coming out at all!) But, water pressure is something that we should all
  be familiar with. Most households receive water from a municipal water
  system. In this method, the water is usually extracted from various
  groundwater sources and then treated to remove impurities. Then, it is then
  pumped to water towers, where gravity takes over to provide the pressure
  that forces the water through pipes, and eventually to our homes. It is also
  important to note that water flow is not the same thing as water pressure.
 Water flow is the result of your water pressure on the amount of water
  available for delivery (volume). Low water flow could be a result of an
  obstruction on the water line, and old pipe with contain mineral build-up or
  corrosion that reduces the pipe’s internal diameter. So, if a water pressure
  gauge is reading at an acceptable level but the pressure seems off, it may
  be a flow problem.
        How Do We Get Water in Our
                Homes?
   Tower, Tank and Pump:
       A water tower is an incredibly simple
        device. Although water towers come in
        all shapes and sizes, they all do the
        same thing: A water tower is simply a
        large, elevated tank of water. Water
        towers are tall to provide pressure.
        Each foot of height provides 0.43 PSI
        (pounds per square Inch) of pressure.
        A typical municipal water supply runs at
        between 50 and 100 PSI (major
        appliances require at least 20 to 30
        PSI). The water tower must be tall
        enough to supply that level of pressure
        to all of the houses and businesses in
        the area of the tower. So water towers
        are typically located on high ground,
        and they are tall enough to provide the
        necessary pressure. In hilly regions, a
        tower can sometimes be replaced by a
        simple tank located on the highest hill
        in the area.
   In most towns, the water people
    drink comes from either a well, a
    river or a reservoir (normally a
    local lake). The water is treated in
    a water treatment plant to
    remove sediment (by filtration
    and/or settling) and bacteria
    (typically with ozone, ultraviolet
    light and chlorine). The output
    from the water treatment plant is
    clear, germ-free water. A high-lift
    pump pressurizes the water and
    sends it to the water system's
    primary feeder pipes. The water
    tower is attached to the primary
    feeders quite simply, as shown in
    this diagram:
   In a city, tall buildings
    often need to solve their
    own water pressure
    problems. Because the
    buildings are so tall, they
    often exceed the height
    that the city's water
    pressure can handle.
    Therefore, a tall building
    will have its own pumps
    and its own water towers.
Finally water arrives
              Water supply
              The water supply system brings cold
               water into the home under pressure.
               The water is piped in through a main
               supply line, usually from either a well,
               spring or municipal water supply. If the
               home has a water filtration or softening
               system it is most effective when
               positioned close to the point where the
               water supply enters the home. After
               entering the home, some of the water
               is immediately diverted to the water
               heater. At this point the hot and cold
               branch lines are run to stub outs for
               the various fixtures throughout the
               home. Small supply lines, are used to
               carry water from the stub outs to the
               fixtures.
           
               The water heater is usually positioned
               close to the point where the main
               water line enters the home.
                                 Pipes
 Why Pipes Burst
 When water freezes, it expands. That's why a can of soda explodes if it's
  put into a freezer to chill quickly and forgotten. When water freezes in a
  pipe, it expands the same way. If it expands enough, the pipe bursts, water
  escapes and serious damage results.
 Surprisingly, ice forming in a pipe does not typically cause a break where
  the ice blockage occurs. It's not the radial expansion of ice against the wall
  of the pipe that causes the break. Rather, following a complete ice blockage
  in a pipe, continued freezing and expansion inside the pipe causes water
  pressure to increase downstream -- between the ice blockage and a closed
  faucet at the end. It's this increase in water pressure that leads to pipe
  failure. Usually the pipe bursts where little or no ice has formed. Upstream
  from the ice blockage the water can always retreat back towards its source,
  so there is no pressure build-up to cause a break. Water has to freeze for
  ice blockages to occur. Pipes that are adequately protected along their
  entire length by placement within the building's insulation, insulation on the
  pipe itself, or heating, are safe.
                 References:
 www.howstuffworks.com
 www.weather.com
 www.lowes.com
 FriedHoffer, BOB: Physics in the Home
 Betts, John: Essentials of Applied Physics

				
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