# Environmental Engineering Questions and Answers – Layout of Distribution System

This set of Environmental Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Layout of Distribution System”.

1. The method of distribution of water is divided into how many types?
a) 1
b) 2
c) 3
d) 4

Explanation: The method of distribution of water is divided into 3 types and it includes gravity system, pumping system and combined gravity and pumping system.

2. In which of the following distribution system, the clean water flows entirely under gravity?
a) Gravity system
b) Pressure system
c) Combined gravity and pumping system
d) Pumping system

Explanation: The purified water in gravity system flow entirely under gravity. It is the most reliable and economical distribution system.

3. The pressure in the distribution mains does not depend on ____________
a) Altitude to supply water
b) Fire fighting requirements
c) Availability of funds
d) Quality of water

Explanation: The pressure in the distribution mains depends on the height to which water is required to be supplied, fire fighting requirements, whether the supply is metered or not and availability of funds.

4. The pressure in distribution mains in a residential building up to three storeys is ____________
a) 2kg/cm2
b) 5kg/cm2
c) 7kg/cm2
d) 10kg/cm2

Explanation: The pressure in distribution mains in a residential building up to three storeys is 2kg/cm2 and when it is between 3-6 storeys, the pressure is 3kg/cm2.

5. There is a 8 storey residential building in Lucknow. What is the pressure in the distribution mains?
a) 2kg/cm2
b) 5kg/cm2
c) 7kg/cm2
d) 10kg/cm2

Explanation: When the height of residential building is between 6 to 10 storey, the pressure in the distribution mains lies between 4 to 5.5kg/cm2.
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6. The velocity of water in a 10 cm diameter pipe should be ____________
a) 0.2m/Sec
b) 0.5m/Sec
c) 0.9m/Sec
d) 1.2m/Sec

Explanation: The velocity of water in a 10 cm diameter pipe should be 0.9m/Sec
Which is 1.2m/Sec when the diameter of pipe is 15cm.

7. In which system of water supply, water is available for 24 hours but uneconomically used?
a) Continuous supply
b) Fixed supply
c) Intermittent supply
d) Low supply

Explanation: In continuous water supply, water is wasted due to a continuous supply of water for 24 hours of the day or long duration of flow.

8. In which system of water supply, water is supplied only during fixed hours of the day?
a) Continuous supply
b) Fixed supply
c) Intermittent supply
d) Low supply

Explanation: In Intermittent supply, water is supplied to the consumer during fixed hours of the day and is adopted when sufficient pressure is not available or sufficient quantity of water is not available.

9. The velocity of water in the pipe is 1.8m/Sec. What is the diameter of pipe used?
a) 10cm
b) 15cm
c) 25cm
d) 40cm

Explanation: It is the maximum diameter of the pipe for which the velocity of water should not be less than 1.8m/Sec.

10. The hourly demand rate is constant throughout the day.
a) True
b) False

Explanation: The hourly demand rate is not constant throughout the day, it is more during morning and evening and less during other parts of the day.

11. According the mass curve method, the storage capacity is defined as ____________
a) Maximum excess of supply / Maximum excess of demand
b) Maximum excess of supply * Maximum excess of demand
c) Maximum excess of supply – Maximum excess of demand
d) Maximum excess of supply + Maximum excess of demand

Explanation: A mass curve of demand is the cumulative demand curve, which is obtained by continuously adding the hourly demands and plotting it against time.

12. _______ causes hoop tension in pipe shell.
a) Internal water pressure
b) External water pressure
c) Water hammer
d) Longitudinal stress

Explanation: Internal water pressure causes hoop tension in pipe shell and its magnitude is given by f = pd/2t where p is the internal pressure of water, d is the diameter of the pipe and t is the thickness of pipe shell.

13. The water supply pipes are buried underground. The load on the buried pipe due to earth filling is given by ____________
a) W = C*Y*B
b) W = C*Y/B
c) W = C*Y*B2
d) W = C*Y2*B

Explanation: According to Marston, the load W on buried pipes due to earth filling is given by W = C*Y*B2 where, ‘C’ is the coefficient which depends on soil, ‘Y’ is the unit weight of back fill material and ‘B’ is the width of the trench.

14. Which of the following stress in pipe depends on temperature?
a) Internal water pressure
b) Stress due to foundation reaction
c) Longitudinal stress
d) Temperature stress

Explanation: Temperature stress is caused in pipes when they are laid above ground. When they are subjected to temperature variation, changes in the length of pipe takes place.

15. Pipe corrosion can be minimized by ____________
a) Removal of copper sulfate
d) Removal of dissolved oxygen

Explanation: Pipe corrosion can be minimized by pH adjustment, control of calcium carbonate, removal of dissolved oxygen, removal of carbon dioxide and by the addition of sodium silicate.

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