Lecture 4 - Water Pumping Flashcards
Water distribution systems are made up of networks of discrete components:
pipes, fittings, pumps, valves, and storage tanks
Needed to determine the operating point of the pump?
A pump head-characteristic curve (H-Q curve of the pump)
and
system-head-capacity curve (H-Q curve of the piping system)
Demand Considerations
- By population, by survey of establishments
- Per capita daily consumption
- Demand Projections
- Demand Fluctuations
Price Elasticity of Water Demand
- willingness of consumers or users to purchase
- Demand vs. Requirement
- willingness of consumers to give up water use in the face of rising prices, or conversely, the tendency to use more as price falls.
high (price) = low (water demand) & high (revenue)
The use of price elasticity of water has been applied worldwide, and some important achievements have been made. The following schematic may depict the general trend of this principle
If the price elasticity for water is -0.5%, what does this mean?
high avg. demand, high change in price
What is WDS ?
Sir, tangina mo, pakyu
gravity distribution
requires a reservoir at a sufficient elevation above the city so that water can reach any part of the distribution system with adequate pressure.
tree-like distribution
system with many dead ends is unsatisfactory because water may become stagnant at the extremities of the system
single main distribution
system is one in which a single main serves both sides of the street
double main distribution
system there is a main on each side of the street.
4 Types of WDS
gravity distribution
tree-like distribution
single main distribution
double main distribution
residential districts Pressure Requirements
410 kPa at the hydrant are recommended for fire fighting
commercial districts Pressure Requirements
minimum pressure of 520 kPa is tolerable, but higher pressures must be provided in districts with tall buildings
fire departments use _____ to develop necessary fire pressure.
motor pumpers
The maintenance of high pressure in mains means?
increased pumping cost and usually also increased leakage.
domestic needs Faucet pressures
35 kPa are satisfactory
a total pressure at the main should be? (Domestic)
240 KPa
Elevated storage may be used advantageously for?
pressure stabilization
Most surface reservoirs are covered to prevent contamination by?
animals, birds, and humans, and by shutting out sunlight, the growth of algae
If topography does not permit sufficient head from a surface reservoir, a ____ may be used to gain necessary height
standpipe or elevated tank
Water level fluctuation in standpipe is limited to?
10 meters
Standpipes over _____ high are not recommended.
15 meters
Minor distribution mains with fire hydrant in residential, business districts and street mains for domestic respectively.
> 150 mm
250 mm
50 mm
___ at summits and ___ at low points.
Air relief valves, drain valves
Gate valves should be not more than ___ apart
400 m
Gate valves ___ are placed in manholes.
> 300 mm
Smaller valves are accessible from the street through?
cast iron valve boxes
Design of WDS (Descriptions))
- Fire hydrants should be not more than 150 m apart to avoid excessive head loss in small diameter fire hose.
- Preferably located at intersections
- Flush hydrants to prevent interference with traffic.
- Wall hydrants in commercial districts.
- Post hydrants for easy location.
- In cold climates, the valve is located below the ground.
- A drain valve should be provided.
The basic requirement of pipes in WDS are?
adequate strength and maximum corrosion resistance
Planning Steps for WDS Development
- Obtain data on, or estimate, the future population of the community, and study local conditions to determine the quality of water that must be provided. 2. Locate one or more sources of water of adequate quality. 3. Provide for the necessary storage of water, and design the works required to deliver the water from its source to community. 4. Determine the characteristics of water and establish water quality requirements. 5. Design water-treatment facilities. 6. Plan and design the distribution system, including distribution reservoirs, pumping stations, elevated storage, layout and size of mains and location of fire hydrants. 7. Provide for the establishment of an organization that will maintain and operate the supply, distribution and treatment facilities.
