Pipes, Valves, Fire Hydrants

8/22/2019 Pipes, Valves, Fire Hydrants

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Environmental Engineering-I

Prof. Dr. Muhammad Zulfiqar Ali Khan

Engr. Muhammad Aboubakar Farooq

Department of Civi l Engineering

The University of Lahore

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Water Supply Pipes

Valves

Fire Hydrants

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Water Supply Pipes

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Various types of pipes are available for thepurpose.

Following points should be considered forselection:

I. StrengthII. Carrying Capacity (size/diameter)

III. Durability (life)

IV. First CostV. Jointing & Maintenance Cost

VI. Type of Water to be conveyed (nature)

VII. Transportation Cost


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Types of Pipes

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1. Cast Iron Pipes2. Steel Pipes

3. Ductile Pipes

4. Galvanized Iron Pipes

5. Concrete Pipes

6. Asbestos Cement Pipes

7. Polyvinyl Chlorine (PVC) Pipes


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Types of Pipes

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1. Cast Iron Pipes: Most widely used for city water supplies.

Average life = 100 Years

Corrosion may reduce its capacity by 70%.

Must be lined with cement or bitumen.

C = 130 for New Pipes

C = 100 for Old Pipes (for designing).

Where C = Coefficient of Roughness inHazen-William Formula.


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Types of Pipes

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2. Steel Pipes:

Contains Less Carbon than Cast Iron Pipes.

Frequently used for TRUNK MAINS.

Much Stronger and Lighter than C.I. Pipes. Cheaper than C.I. Pipes.

Can not withstand Vacuum, hence collapse.

Highly Susceptible to Corrosion, hence high

Maintenance charges required.

Average Life = 25

50 Years.


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Types of Pipes

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3. Ductile Pipes: Similar to C.I. pipes except Increased

Ductility (Property of a metal, of beingcapable to be drawn out into a wire).

Ductile iron is produced by adding acontrolled amount of Mg into molten ironof low Sulphur and phosphorus content.

Stronger, Tougher & more Elastic than C.I.

More Expensive than C.I. Pipes.


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Types of Pipes

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4. Galvanized Iron (G.I.) Pipes: Produced by dipping Cast Iron pipes in

Molten Zinc.

In this pipe, zinc erodes and Cast ironremains same.

Resistant to Corrosion.

Mainly used for plumbing (Small diameter

pipes).


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Types of Pipes

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5. Concrete Pipes: Usual size of RCC Pipes is 400mm and

above.

Not subjected to corrosion.

Manufactured at or near site as

transportation and handling cost is high.

Average Life = 75 Years.

C = 138 to 152


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Types of Pipes

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6. Asbestos Cement (A.C.) Pipes: Sizes = 100mm to 600mm.

Average life = 30 Years

Immune to actions of Acids, Salts, Soils,Corrosions.

Less Cost for laying and jointing.

Less pumping cost due to less friction. Lung Cancer can happen by inhaling A.C.

C = 140.


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Types of Pipes

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7. Polyvinyl Chloride (PVC)Pipes: Mainly used for Domestic Plumbing.

Easy to install and easy to handle.

Cheaper in Material Cost.

Weak to sustain load.

Only available upto 350mm diameter size. Expected Life = 25 Years


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Valves

A device for controlling the passage of fluidthrough a pipe or duct, especially anautomatic device which allows movement in

one direction only.Valves are used to:

Regulate flow

Regulate pressure

Cut off supply for repair purposes

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Location of Valves

Two valves at each

intersection.

One valve at firehydrant.

One valve for each

400m length of pipe. On average 8-valves per

kilometer of main.13


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Types of Valves

1. Gate Valve (Sluice Valve):It is used to shut off water supply mains for

repair and generally placed at street

corners where lines intersect.

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2. Butterfly Valve:

These are used in filter Plants and highpressure distribution system in order toshut off supply very slowly to avoid waterhammer.


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Types of Valves

3. Air Relief Valve:

It allows the accumulated air in the pipe to

escape. It also allows the external air to

enter the pipe to break the vacuum.

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4. Globe Valve: (S-Shaped)

They are used in the plumbing system onsmaller pipes. They create a lot of headloss.


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Types of Valves

5. Check Valve:Check valve Permits water to flow in one

direction only and it is used in pumping

station and at apex points in pipe line.

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6. Blow-off Valve:

It is used to drain a line or to remove theaccumulated sediments located at lowpoints.


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Types of Valves

7. Pressure Regulating Valve:They reduce pressure automatically on

down stream side to any desired

magnitude. They function by using the u/spressure to throttle the flow through an

opening like in globe valve.

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Types of Valves

8. Altitude Valve:It is used to close automatically a supply

line to an elevated tank when full.

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Overview of Functioning of Valves

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Fire Hydrants

Used to deliver water from themain for Fire Fighting.

Should have at least two 2 hose

outlets and a larger pumperoutlet.

A single hose stream should

give 1m3/min flow.

Located at street intersections

1-2m from the edge of road.20


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Fire Hydrants

Outlet of the hydrantshould be at least 0.5m

above road surface.

Generally painted in

RED Color for easy

identification.

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Pipes, Valves, Fire Hydrants

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