Chapter 4 Water Distribution Systems Flashcards
Four basic components of water supply systems
- water supply source
- water treatment facilities
- mechanism for forcing water through the system
- a system of piping to transport the water through the community
average daily consumption
the average of the total amount of water used daily in water distribution system over one year
maximum daily consumption
to maximum total amount of water that was used during any 24 hour interval within a three-year period
peak hourly consumption
the maximum amount of water used in any one hour interval over the course of a day
the maximum daily consumption is normally about…
1.5 average daily consumption
what are the two basic categories of water supply sources
surface water
groundwater
which is the more commonly used source of water
surface water
what is the purpose of man-made water impoundments
they can be filled, and left to let many appeared his filter out naturally
4 characteristics of surface water
softer water
more suspended solids and color
more bacterial contamination
depleted more rapidly, low rainfall
two types of ground waters and may be used for domestic systems
wells
Springs
characteristics of groundwater supplies
heart of water
clearer
less bacteria
less quickly affected by periods of drought
two processes of water treatment
adding elements that improve water quality
removing contaminants
two additives that are added to water
fluoride
oxygen
where the four processes that remove contaminants from water during water treatment
- sedimentation- particles fall on water
- filtration- passing water through a set of filters
- coagulation- chemical that causes solid particles to bond together and form larger particles, which can be filtered out
- chemical treatment- adding subtracting chemicals to make the water healthy ( oxygen and fluoride)
are the three means of moving water
gravity
direct pumping
combination
was the most common method of moving water through a water distribution system
combination systems, using elements of both direct pumping and gravity systems, water towers serve as backup pressure sources when system demand is high
for the three common designs for water supply system piping arrangements
tree system- Central primary supply pipe that feeds branch distribution lines, mostly from one direction
circle, or belt system- found in small jurisdictions/ private systems… they form a loop serves the consumer’s own system normally have a directional flow haven of her break correction can be reversed
grid systems- in loop system of pipes connected at standard intervals providing reliable multidirectional flow, most reliable type of water distribution
primary feeders
largest pipes, or mains, in the system convey large quantity of water to various points
secondary feeders
network of intermediate sized pipes reinforce the grid with various loops off primary feeder system. Aid in the concentration of the required flow at any point
distributors
smaller main serving individual fire hydrants and blocks of consumers throughout the system
from a fire protection standpoint one of the grid systems primary advantages is…
hydrants can receive water from two directions, greatly reducing the amount of friction loss in the system
what are some characteristics of well designed grid systems
- two or more primary feeders run by separate routes from the supply source to the community’s high risk industrial districts
- secondary feeders are arranged… Far possible to give two directions of supply at any point
What are the sizes of pipes in a grid system
primary feeders 8-72”
secondary feeders 6-36”
distributors 4-20, can be as small as 2
American Water Works Association currently recommends a minimum diameter of___ for any new pipe installation
8”
what is one of the most important factors in the water supply system
the ability to operate valves promptly during the emergency of equipment breakdown
how do you know if an OS&Y valve is open or closed
the threaded portion of the stem is out of the yoke when the valve is open…. inside when closed
where the two mechanisms used in controlled valves of water distribution system
gate mechanisms
butterfly mechanisms
standard hydrant usually are equipped with a ___ valve opening, and a ___ connection to water main
5” valve opening
6” connection to water main
where the three reasons private water systems usually exist
- water solely for fire protection
- water for sanitary purposes, consumption, and fire protection
- water for fire protection and manufacturing processes
firefighters should be alert for what type of leaks when hydrant is in use
- at the main valve when the valve is closed
- at the drain valve when the main valve is opened but the outlets are capped
- In the water mains near the hydrant
