L- 51Pipe Appurtenances

Environmental Engineering –I

By Prof S S JAHAGIRDAR

Components of Distribution Networks

• Pipes

• Storage Facilities

• Pumps

• Valves

• Hydrants

• Meters

Valves • Purpose of Valves

1. The primary purpose of valves is to allow for isolation of mains or sections of main within the network.

2. Another important function of valves is to control flow or pressure.

1. Sluice or Gate Valve

• Also known as shut off valves or stop valves or isolation valves.

• Used to shut of the supplies wherever desired.

• Useful in dividing water mains in various sections.

Location of isolation valves

• Spacing – 150 to 300 m.

• Also placed on corners.

• Less cost

• Less resistance to flow

• Made up of cast iron with brass mountings

2. Air Relief Valve

• Water flowing through pipes always contain some air.

• Air tries to accumulate at high points.

• Accumulated air interferes with flow.

• Therefore air relief valves are provided at summits.

• Function of air valve to discharge out excess air.

Location of Air Relief Valve

Summit

3. Reflux Valve

• Also known as Check valve or non-return valve.

• Allows water to flow in only one direction.

• They are provided next to pumps to avoid back flow of water after shutting off the pump.

• Back flow of water may damage the pump.

• Pivoted Flat disc is provided, which returns to its original position in case of reverse flow

4. Pressure Relief Valve

• Also known as Automatic cutoff or Safety valves.

• Located at points where pressure is maximum.

• When pressure increases preset value, the valve operates automatically and pressure is reduces.

5. Altitude Valves• Provides automatic filling of elevated

tanks or reservoirs.

• When the altitude control senses a drop in level below the predetermined set point, the valve opens to fill tank. When the level again reaches the set point, the valve will close.

• These are provided to the pipes which supply water to ESRs or stand pipes.

• There are two types

- Single acting and

- Double acting

• Single acting : - flow in one direction only - from the pump side to the tank. A separate discharge line or by-pass arrangement is used for removing the storage water from the tank.

• Double Acting:- an altitude valve which allows flow from the pump to the tank and also allows reserve flow from the tank back through the valve to the distribution system.

Single Acting

6. Scour Valves

• Also known as blow off or wash out valves.

• Located at dead end in dead end distribution system.

• Provided to remove sand and silt deposited in the pipe line.

• Operated manually.

ASSIGNMENT 4 TE –(A)WATER DISTRIBUTION

SYSTEM

1. Find length of equivalent pipe with equivalent diameter 0.5 m if three pipes are connected in

a) Series and

b) Parallel

Pipe Length Diameter

1 2 km 0.6 m

2 1 km 0.5 m

3 3 km 0.7 m

2. Compute distribution of flows in the pipe network shown below by using Hardy Cross method. Take two trials

Use hf = kQ2

3. Compute distribution of flow in the network shown below by using Hardy Cross method. Take two trials.

Use hf = kQ1.85

UNIVERSITY QUESTIONS ON UNIT IV

Objective Questions1. Radial system is reverse of ______

system. (dead end/grid iron/circular/ all of above).

2. To increase the discharge pipes are provided in _____. (series/ parallel/ series or parallel/ cant say).

3. Reflux valve are also known as _____ valves. (shut off/check/cut off/ air relief).

4. Check valve is also known as _____. (reflux valve/non return valve/ both/none of these).

5. Summits are the points of ____ pressure. (high/ low/ equal/none of these).

6. Match the pairs

Group A Group B

Gate valve Located at high pressure points

Air relief valve Used to shutoff the supplies

Reflux valve To provide exit for accumulated air

Safety valve Allows water to flow in one direction

7. In pressure supply mains, water hammer pressure is reduced by providing ______. (sluice valve/air valve/pressure relief valve/ none of these).

8. In equation hf = k.Qn the value of ‘n’ for Hazen Williams formula is _________. (1.85/2/1.7/1).

9.Reflux valve is also known as _______. (gate/ check/scour/sluice).

10. Washout valves are provided at _______ points in the mains. (lowest/ highest/ summit/ all of above).

Theory QuestionsQ1. Give requirements of a good

distribution system. (May 2012, Dec 2010, 5 marks).

Q2. Explain grid iron system of water distribution with neat sketch (May 2012, 5 marks).

Q3. Draw neat sketch of air relief valve and name its parts (Dec 2011, Dec 2009, 5 marks)

Q4. Explain grid iron system of water distribution with neat sketch and mention its advantages (Dec 2011, Dec 2009, 5 marks).

Q5. Explain Hardy-Cross method of analysis of pipe network (Dec 2011, Dec 2010, 9 marks).

Q6. Draw neat sketch of non return or reflux valve and name its parts (May 2011, Dec 2010, 5 marks).

Q7. Explain circular system of water distribution with neat sketch (May 2011, 8 marks).

Q8. Explain Dead end system of water distribution with neat sketch (Dec 2010, 4 marks) .

Q9. Explain equivalent pipe method of analysis of pipe network of a distribution system (Dec 2009, 9 marks).