Household Water By: Zoila Quiroz & Diana Chavez. Overview Terms Pascals Principle Water Pressure Water Tower, Pumps How we get water into our.

Household WaterHousehold Water

By:By:Zoila QuirozZoila Quiroz

&&Diana ChavezDiana Chavez

OverviewOverview

TermsTerms Pascals PrinciplePascals Principle Water PressureWater Pressure Water Tower, PumpsWater Tower, Pumps How we get water into our homeHow we get water into our home PipesPipes Experiment Experiment ClosingClosing

Terms:Terms:

Pressure: defined by the equationPressure: defined by the equationPressure = Force / AreaPressure = Force / Area

UnitsUnits The units of pressure are those of force divided by the The units of pressure are those of force divided by the

units of area. The exact units depend on which system units of area. The exact units depend on which system you are usingyou are using

In scientific units force is measured in Netwons (1 N = 1 In scientific units force is measured in Netwons (1 N = 1 kg m / s2) and area in m2. Pressure has units of N/m2 kg m / s2) and area in m2. Pressure has units of N/m2

In Imperial units force is measured in pounds and area in In Imperial units force is measured in pounds and area in in2. Pressure has units of lbs/in2 (psi for short) in2. Pressure has units of lbs/in2 (psi for short)

More Terms:More Terms:

Atmospheric Pressure: Atmospheric pressure is the pressure Atmospheric Pressure: Atmospheric pressure is the pressure exerted at the surface of a body by a column of air in an exerted at the surface of a body by a column of air in an atmosphere. The pressure varies both with altitude, and weather atmosphere. The pressure varies both with altitude, and weather patterns. Standard is an average atmospheric pressure at sea level, patterns. Standard is an average atmospheric pressure at sea level, and is defined as 1 atmosphere on Earth, equal to 760 millimeters of and is defined as 1 atmosphere on Earth, equal to 760 millimeters of

mercury (760 Torr) and 101,325 Pascals.mercury (760 Torr) and 101,325 Pascals. 1 atmosphere = 14.7 lbs/in2 = 101,000 N/m2 = 1.01325 bars = 760 1 atmosphere = 14.7 lbs/in2 = 101,000 N/m2 = 1.01325 bars = 760

Torr = 32 feet of waterTorr = 32 feet of water True Pressure: The total pressure exerted on a system equal to the True Pressure: The total pressure exerted on a system equal to the

gauge pressure and atmospheric pressure.gauge pressure and atmospheric pressure.Gauge Pressure: The pressure of a system measured by the gauge Gauge Pressure: The pressure of a system measured by the gauge

which excludes atmospheric pressurewhich excludes atmospheric pressure

Pascal’s PrinciplePascal’s Principle

Pascal’s Principle: When a pressure is Pascal’s Principle: When a pressure is applied to a confined liquid, that a applied to a confined liquid, that a pressure is transmitted throughout the pressure is transmitted throughout the extent of the liquid.extent of the liquid.

Pressure exerted on an enclosed liquid is transmitted Pressure exerted on an enclosed liquid is transmitted equally to every part of the liquid and to the walls of the equally to every part of the liquid and to the walls of the container. (Pascal's principle) container. (Pascal's principle)

A A manometermanometer relies on Pascal's principle to measure relies on Pascal's principle to measure pressure in gases. pressure in gases.

Pascal's principle is important in understanding Pascal's principle is important in understanding hydraulicshydraulics, the study of the transfer of forces through , the study of the transfer of forces through fluids. fluids.

Water PressureWater Pressure

Water Pressure ExplainedWater Pressure Explained   As we turn on the kitchen faucet or start a bath, how the water is coming 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 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 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 be familiar with. Most households receive water from a municipal water system.  In this method, the water is usually extracted from various system.  In this method, the water is usually extracted from various groundwater sources and then treated to remove impurities. Then, it is then groundwater sources and then treated to remove impurities. Then, it is then pumped to water towers, where gravity takes over to provide the pressure 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 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. 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 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 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 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 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 gauge is reading at an acceptable level but the pressure seems off, it may be a flow problem. be a flow problem.

How Do We Get Water in Our How Do We Get Water in Our Homes?Homes?

Tower, Tank and Pump:Tower, Tank and Pump: A water tower is an incredibly simple A water tower is an incredibly simple

device. Although water towers come in device. Although water towers come in all shapes and sizes, they all do the all shapes and sizes, they all do the same thing: A water tower is simply a same thing: A water tower is simply a large, elevated tank of water. Water large, elevated tank of water. Water towers are tall to provide towers are tall to provide pressurepressure. . Each foot of height provides 0.43 PSI Each foot of height provides 0.43 PSI (pounds per square Inch) of pressure. (pounds per square Inch) of pressure. A typical municipal water supply runs A typical municipal water supply runs at between 50 and 100 PSI (major at between 50 and 100 PSI (major appliances require at least 20 to 30 appliances require at least 20 to 30 PSI). The water tower must be tall PSI). The water tower must be tall enough to supply that level of pressure enough to supply that level of pressure to all of the houses and businesses in to all of the houses and businesses in the area of the tower. So water towers the area of the tower. So water towers are typically located on are typically located on high groundhigh ground, , and they are tall enough to provide the and they are tall enough to provide the necessary pressure. In hilly regions, a necessary pressure. In hilly regions, a tower can sometimes be replaced by a tower can sometimes be replaced by a simple tank located on the highest hill simple tank located on the highest hill in the area.in the area.

In most towns, the water people In most towns, the water people drink comes from either a well, a drink comes from either a well, a river or a reservoir (normally a river or a reservoir (normally a local lake). The water is treated in local lake). The water is treated in a a water treatment plantwater treatment plant to to remove sediment (by filtration remove sediment (by filtration and/or settling) and bacteria and/or settling) and bacteria (typically with ozone, ultraviolet (typically with ozone, ultraviolet light and chlorine). The output light and chlorine). The output from the water treatment plant is from the water treatment plant is clear, germ-free water. A high-lift clear, germ-free water. A high-lift pump pressurizes the water and pump pressurizes the water and sends it to the water system's sends it to the water system's primary primary feeder pipesfeeder pipes. The water . The water tower is attached to the primary tower is attached to the primary feeders quite simply, as shown in feeders quite simply, as shown in this diagram: this diagram:

In a city, In a city, tall buildingstall buildings often need to solve their often need to solve their own water pressure own water pressure problems. Because the problems. Because the buildings are so tall, they buildings are so tall, they often exceed the height often exceed the height that the city's water that the city's water pressure can handle. pressure can handle. Therefore, a tall building Therefore, a tall building will have its own pumps will have its own pumps and its own water towers. and its own water towers.

Finally water arrivesFinally water arrives Water supplyWater supply The water supply system brings cold The water supply system brings cold

water into the home under pressure. water into the home under pressure. The water is piped in through a main The water is piped in through a main supply line, usually from either a well, supply line, usually from either a well, spring or municipal water supply. If the spring or municipal water supply. If the home has a water filtration or softening home has a water filtration or softening system it is most effective when system it is most effective when positioned close to the point where the positioned close to the point where the water supply enters the home. After water supply enters the home. After entering the home, some of the water entering the home, some of the water is immediately diverted to the water is immediately diverted to the water heater. At this point the hot and cold heater. At this point the hot and cold branch lines are run to stub outs for branch lines are run to stub outs for the various fixtures throughout the the various fixtures throughout the home. Small supply lines, are used to home. Small supply lines, are used to carry water from the stub outs to the carry water from the stub outs to the fixtures. fixtures.

The water heater is usually positioned The water heater is usually positioned close to the point where the main close to the point where the main water line enters the home.water line enters the home.

PipesPipes Why Pipes BurstWhy Pipes Burst When water freezes, it expands. That's why a can of soda explodes if it's 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 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 pipe, it expands the same way. If it expands enough, the pipe bursts, water escapes and serious damage results. escapes and serious damage results.

Surprisingly, ice forming in a pipe does not typically cause a break where 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 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 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 in a pipe, continued freezing and expansion inside the pipe causes water pressure to increase downstream -- between the ice blockage and a closed 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 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 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, 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 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 ice blockages to occur. Pipes that are adequately protected along their entire length by placement within the building's insulation, insulation on the entire length by placement within the building's insulation, insulation on the pipe itself, or heating, are safe.pipe itself, or heating, are safe.

References:References:

www.howstuffworks.comwww.howstuffworks.com www.weather.comwww.weather.com www.lowes.comwww.lowes.com FriedHoffer, BOB: FriedHoffer, BOB: Physics in the HomePhysics in the Home Betts, John: Betts, John: Essentials of Applied PhysicsEssentials of Applied Physics