Presentation Transcript

1. Household Water Supply
2. The water supply in a house is a managed pressure system Pipe sizing is used to control pressure in the distribution throughout the house Valves are used to control supply at critical points, for example a valve is installed at the point of connection to all water appliances so that they may be serviced without shutting off the water supply to the house. Compression chambers are used to control pressure fluctuations at critical points, for example at faucets to prevent water hammer Two basic branch distribution methods are employed for water supply—parallel and series. Either one may be used, and in some instances both are used simultaneously in the same branch Identify and describe the function of Rural water supply Water main (or well) Types of wells that can supply water Possible pumping sources to deliver the water Types of storage tanks for well systems Municipal water supply Main water line and control valve Cold water supply Hot water supply, including heating system Pipe runs and rises Stops, valves and faucets Describe what happens when “water hammer” occurs. Explain how an air chamber dampens this phenomenon.A suitable entry should be made in the student work log
3. 1. Municipal Water Supply Systems Water is vital to everyday life, and throughout history people have devised systems to make getting and using it more convenient. Early Rome had indoor plumbing, meaning a system of aqueducts and pipes that terminated in homes and at public wells and fountains for people to use. Modern water supply systems get water from a variety of locations, including aquifers, lakes, rivers, wells, desalinated seawater, and other sources. The water is then purified
4. For many municipalities large ponds or lakes are used as water sources. Most systems work in a similar fashion to what is given below. A large pipe extends out into the lake to a large concrete and metal structure on the lake bottom which acts as the intake filter. This filter screens out only the largest of debris, including wood or large rocks. A set of large electric submersible pumps in a pump house building on the shoreline suck the water into a system of sand and other filters to screen out large and small debris, including fish, leaves, or gravel. (Bay Bulls Big Pond pictured in background)
5. The water then is pumped through a set of pipes where it is chlorinated to kill bacteria and any small multicelled organisms that manage to make it through the filters. The water is then fluoridated to benefit public dental health. Finally, the water is tested by various sensors to determine if it is safe to drink, and pumped to other locations.There are various pumping stations throughout the region that supply a constant water pressure to the areas it serves. Water pipes lead to almost every house and business in the area, as well as to fire hydrants.
6. 2. Ground Source Water Wells In some areas there is no municipal water system. To get fresh water, wells must be used. Some precipitation that falls to the ground surface infiltrates the ground and becomes groundwater. Groundwater is defined as sub-surface water that fills openings and pore spaces in soil and rock layers. Below the ground surface is an unsaturated zone which water travels through to reach lower zones. The water table is the point at which the ground is completely saturated. Below this level the pore spaces between every grain of soil and rock crevice completely fill with water.
7. Types of wells An aquifer is a layer of sand, gravel or sediment that contains water that can be used as wells. Dug Well We can dig shallow wells (Dug Well) that tap into the upper part of the water table. These were commonly used in days prior to heavy machinery. If something affects the water table these can dry up from time to time. You need to ensure that there is water available close enough to the surface prior to starting to dig. Since these are usually dug by hand or using smaller excavating machinery they are seldom more that 30 feet deep.
8. Driven wells are still common today. They are relatively inexpensive. They are built by driving a small-diameter pipe (well-point) into soft earth, such as sand or gravel. This is done by using a sledge hammer or a mechanical hammer of some sort. Pipe is added as it gets further in the ground. A screen is usually attached to the bottom of the pipe to filter out sand and other particles. Problems? They can only tap shallow water (50 or 60 feet below ground), and because the source of the water is so close to the surface, contamination from surface pollutants can occur. Types of well-points
9. Drilled wells obtain water from deep groundwater aquifers. Drilled wells are typically about 45 m (150 ft) deep and have a diameter of 15 cm (6 in). If they are properly constructed and maintained, they are not as likely to have contamination, but because of their depth they may have mineral or chemical additives that could affect the quality of your water. Chemical testing should be conducted on every new drilled well. The Water Resources Act states that a provincially licensed well driller must construct all drilled wells.
10. Bored wellsA bored well is constructed when low yielding groundwater sources are found relatively close to the surface, usually under 30 m (100 ft.). Bored wells are constructed using a rotary bucket auger. They are usually completed by perforating the casing or using a sand screen with continuous slot openings.One advantage of bored wells is the large diameter of the casing, from 45-90 cm (18-36 in.). It provides a water storage reservoir for use during peak demand periods. A disadvantage of utilizing a shallow groundwater aquifer is that it relies on annual precipitation for recharge. Water shortages may occur following long dry periods in summer and extended freeze up during winter months.
11. We commonly call these deep wells artesian wells. A true artesian well is flowing, which means there is pressure in the well so that you don’t need pumps.
12. Wells
13. With most wells a pump has to be installed in order to get the water to where it is to be used. There are a variety of pumps depending on the type and depth of well you have, distance from source to building, amount of usage and maintenance of the pump. First you must determine what your water usage will be then find the right pump and storage tank combination to ensure you always have adequate water supply at the right water pressure. There are two categories of pumps: Shallow-well pumps which are above ground and Deep-well pumps which are installed inside the well casing
14. Wells less than 25’ are called shallow. The shallow-well pump, also called a lift pump, is at ground level and work by creating a vacuum and sucking (lifting) the water out of the well. There are four main types of this pump. These all have a motor attached to drive the action inside. Reciprocating Pump – Uses a piston that moves back and forth in a cylinder to create a vacuum. Centrifugal Pump – Uses a spinning metal disk called an impeller to throw water off the outer edge to create the vacuum. Jet Pump – Also uses an impeller but has a jet or ejector that acts to improve the vacuum and amount of water moved. Rotary Pump – This pump uses a helical rotor to create the vacuum that draws the water
15. For wells deeper than 25’ a pumping device must be installed near inside the well-casing near the water table. The pumps are similar to and work in the same way as shallow-well pumps but they must push the water up the well. The four types are: The reciprocating pump – uses a piston that drops into the water and pushes the water up the pipe. Centrifugal Pump – a submersible pump that uses impellers to push the water up to the tank. Jet Pump – only the ejector in this pump is submersed. The pump forces a small amount of water through a venturi tube which forces a larger amount of water up the pipe. Helical Pump – Can lift water up to 500’. Works in a similar manner to the shallow-well rotary pump
16. With any water system it is important to maintain a steady supply of water at a steady pressure. Municipal water systems will use pumping stations or water towers which are large elevated water tanks. In the case of a privately owned water supply a tower is not feasible. A hydro-pneumatic tank can be used. These tanks contain water and air. As the water is pumped into the tank the air pressure increases. The pump shuts off once the pressure reaches a certain level (about 50psi). When you open a valve in your house (sink, shower, etc) the air forces the water out of the tank and into the water lines.
17. Once we have the water flowing to our homes what happens then? As the water comes into our homes smaller sized piping is used. Typically the pipe from the main water supply to our homes is ¾” to 1” in size. Once inside the home the pipe size is reduced as it goes to the various fixtures. Typically ½” piping is used. As the pipe is reduced in size it increases the pressure of the water in the system. Constant water pressure is important so that we get water where we need it, when we need it in our buildings.
18. We control the water in our homes through a variety of valves. In a municipal system every home has a water main shutoff valve. This valve is owned by the city/town and can be shutdown if there is trouble with water in the building or if your bill is not paid!
19. Within the home itself it is important to have valves placed at strategic locations. This will ensure that if one part of the system needs to be shut down the other parts can still function. There are a variety of valve types. Here are a few: Ground key or stop valve has a hole through the center and can be shut off with a ¼ turn. The gate valve uses a screw mechanism that puts a gate in place to shut off the water supply. A compression valve uses a screw mechanism that pushes a rubber washer over a hole to stop the flow.
20. Since different people like different water temperatures and certain appliances need different temperatures of water we adjust the water temperature through the use of valves called faucets. The faucet allows us to mix the hot and cold water to obtain the temperature we want.
21. The water that comes into our homes is cool fresh water. Once inside certain fixtures and appliances will need this cold water. But we also need hot water for bathing, clothes and dish washing, etc. We use a water heater to heat the water then distribute it to where it is needed. Parallel Distribution System Various fixtures in the building Main Water line Hot water tank
22. Once inside the home or building the supply systems may be installed with branch circuits in series or in parallel, or a combination of both. The manner of distribution affects pressure, rate of flow, and how long it takes for hot water to reach a particular appliance. The ideal for water flow is to have shorter paths. From water main Various fixtures in the building Hot Water Tank Series distribution
23. The run of pipe (how long it is) and the rise (how high up it goes) doesn’t matter as long as you have sufficient pressure. If there isn’t enough water force at a certain point this may be remedied by increasing the pressure on the system. The balance comes in not having too much pressure in one part and not enough in another. Typically homes will have sufficient pressure from the system they are on. This can be controlled through the placement of fixtures and the sizing of pipe. Larger buildings may have to have pumps at certain points to increase the pressure where needed. Some high rise buildings will pump water to holding tanks at the top of the building and use gravity to produce the pressure needed.
24. Activity:Using the book Modern Plumbing Ch. 11 by Keith Blankenbaker complete the following: Explain the four types of wells. p.171 How is pressure maintained in a water supply system? (municipal and well)p. 183 What is the purpose of valves in a water system? P. 245 What is water hammer and how can it be controlled? p. 107 & p. 348 Describe two types of pumps. Describe two types of valves used in a plumbing system