Water Distribution Flashcards
First water distribution network
a. Roman aqueduct system – 2000 years old and still standing. It’s what allowed for ~1mil people cities…
First US water system was created in ____ in the city of ____
1801
Philidephia
When did Tucson Water Company first start delivering water?
1881
Describe early water mains.
d. Early 1800 – wooden water mains. “Plugging” a line came from the fact that you literally bored a hole in the wooden pipes and then had to replug it.
What are the two sources of water TFD uses?
Static and pressurized
Static water
i. Any source of water that needs to be mechanically moved into a fire apparatus
1. Lakes/ponds/rivers
2. Portable tanks
3. Cisterns
4. Swimming pools
5. Test pits
What is drafting?
ii. Drafting is the process of raising water from a static source to the pump.
1. TFD only drafts at the test pit during pump tests and Water Tender Shuttle Operations
3 things that affect drafting
a. Lift – the difference between the level of the water and the center of the pump.
b. Vacuum – an enclosed space from which matter, especially air, has been partially removed.
c. Atmospheric pressure – the weight of a column of air at a given location on the surface of the earth
i. On average, at sea level, the atmospheric pressure is 14.7 psi
ii. Tucson is normally 13.9 psi
What is Tucson’s atmospheric pressure?
13.9psi
How does drafting work?
- By decreasing the pressure (mmHg) in the pump and hose below atmospheric pressure, the water is forced into the hose. Atmospheric pressure is still pushing on the static water source. The pressure/force on the water source will push the water up the hose
Pressurized water
Any source that will flow freely into a fire apparatus.
Booster tanks
Water Tenders
Hydrants
Booster tank details
a. Must be able to deliver 250GPM to the pump gravity fed if the tank is less than 750 gallons
b. Must be able to deliver 500GPM to the pump (gravity fed) if the tank is 750 or more.
Water tender details
a. Bring water to places where there are few or no hydrants
b. WT20 (8779) carries 2500 gallons of water (10 tons)
(Yes, I know WT20 has been moved around, but we haven’t gotten any official written documentation of what station its at, so I’m going off of the PP we got.)
Hydrant details
a. Fire hydrants are part of a water distribution system that is designed to meet the needs of the community it serves.
b. Hydrants are placed for the specific purpose of providing an adequate and reliable water supply for fighting fires
Components of a distribution system
Supply source Treatment plants Reservoirs Mains Hydrants
Supply sources
i. There are 206 active or standby wells in the Tucson water system
ii. 91 million gallons per day come from well within Tucson (2014 data)
iii. CAP – 57 million gallons of blended water (2014 data)
iv. CAP aka Clearwater
Treatment plants
i. Treated with chlorine at well sites
ii. Monitored throughout the system at reservoirs and other sites
iii. Additional chlorine can be added throughout the system as needed
Reservoirs
i. Reservoirs are filled from well sites
ii. 57 total reservoirs
iii. 29 are over 1 million gallons
iv. 28 are under 1 million gallons
Mains
i. Booster stations boost water along mains.
ii. Grid system
1. Pressure in a grid system is created by gravity from reservoirs at higher elevation and from pumping stations
Advantages of using grid system of mains
a. Helps reduce dead end mains
b. Loop or grid systems will reduce friction lose by a power of 4
c. Only one or two hydrants shut down if a main is broken
Friction loss in mains
a. Total pressure lost in the system while water is forced through pipes, fittings, valves, etc.
b. 1000GPM through 100ft of pipe will lose:
i. 52psi in a 6in line
ii. 12.8psi in a 8in line
iii. 1.78psi in a 12in line
Main sizes
- From reservoirs: 16-56in
- Primary feeders: 16in-24in
- Secondary feeders: 12in-18in
- Distributors or laterals: 8in if dead end main, 6in being the smallest line to a hydrant
Three things that reduce flow
- Sedimentation
a. Dirt and other products that collect in the system - Incrustation
a. Mineral deposits inside of pipes, valves, fittings etc.
b. Hard water. It’s everywhere. - Tuberculation
a. Actual pipe breakdown
Zone stats
- Due to elevation changes in Tucson (SE to NW), the city must be broken into zones to prevent overpressure in the mains.
- 22nd & Wilmot is the same elevation as A mountain
- A pipe laid from Houghton rd to the Santa Cruz River would create 300psi at the river due to 600-700ft elevation change.
- There are 19 zones within the Tucson Water system
- ~105ft elevation change within zone
- Normal pressure will range from 40-85psi
- Head pressure is .434psi per foot in elevation loss
- All zones are connected and then separated by valves
- Valves are computer monitored and controlled
Valves types
- Indicating – OS&Y, PIV, Ball Valve
a. OS&Y: outside stem and yoke
A variation on the gate valve
b. PIV: Post indicator valve - Non-indicating – gate, ball, butterfly, and others
Who sets the standards on water pressure?
American Water Works Association (AWWA)
Hydrant pressure types
- Static – the pressure in the hydrant when it is closed, water at rest
- Normal operating – pressure found in a water distribution system during periods of normal consumption demand.
- Residual – pressure left in the system when a hydrant is flowing.
- Flow – the pressure of water in motion
Hydrant pressure testing is done at?
iii. Working pressure is 150 psi, factory tested at 300psi
How many hydrants in the Tucson water system?
20867
How many hydrants in the city limits?
14324
Types of hydrants
Dry a. Foot piece b. Barrel c. Bonnet d. Operating stem e. Main valve f. Drain Wet - not really used. Maybe one downtown.
Hydrant mechanisms
- Compression (most common, 99%)
a. Valve move s independently on a vertical axis. Seats against the base of the hydrant.
b. Closes with pressure. Opens against pressure.
c. Brands: Dresser and Mueller - Knuckle joint or Cory
a. Scissors type valve
b. Brands: Pacific States and Iowa - Slide gate
a. Gates move vertically on a stem.
b. TFD has no slide gate hydrants - Wet
a. Pressurized at each outlet
b. Outlets are controlled independently, usually with a compression style valve
High pressure hydrants
- Reflective yellow bands around the barrel
- 200psi or greater static pressure, 95 or greater residual
- Do not use 5in hose, as it is not rated for that high a pressure for that long. Use 2.5in
Hydrant color coding
used to have the steamer color coded…
- Green/no paint = 1000+gpm
- Orange = 500-999gpm
- Red = less than 500gpm
- Tucson water is now painting them all silver, but you might find one or two….
Hydrant formula (the real one, not the made up one)
29.7 x D^2 x √flow pressure x co-efficient = GPM
D = discharge diameter = 4.5
Flow pressure from pitot tube and gauge
Co-efficient = .9
Hydrant safety rules
- Open and close slowly to prevent water hammer
- Never kick a hydrant wrench open or closed
- Make sure hydrant is closed before removing caps
- Protect hose from dumb Tucson drivers.
Also, no stand in danger zones!
Hydrant spacing
- Residential – 800ft on 6in main
- Multiple housing – 500 on 8in main
- Industrial – 300ft on a 12in main
Fire code on hydrant spacing
- Spacing between hydrants (800, 500, or 300)
- 3ft clearance around hydrant
- 2-7ft from curb
- Streamer outlet 16in from ground
- Blue retroreflectors in the street
Testing of hydrants and out of service procedures
- Tested and maintained by Tucson Water Department every 4 years
- Out of service procedure
a. Hydrant ring
b. Notify fire alarm
c. Email water department
d. CAD hydrant OOS information displayed.
