# Environmental Engineering Questions and Answers – Joints and Shapes of Sewers and Cleaning, Maintenance and Ventilation of Sewer

This set of Environmental Engineering Interview Questions and Answers for Experienced people focuses on “Joints and Shapes of Sewers and Cleaning, Maintenance and Ventilation of Sewer”.

1. How many types of joints are present in the sewer?
a) 3
b) 4
c) 5
d) 7

Explanation: There are 7 types of joints in the sewer, namely Bell and spigot, Collar, Simplex, Flexible, Mechanical and Open joints.

2. The ratio of cement mortar used in Bell and spigot joint is?
a) 1:1
b) 1:6
c) 2:1
d) 1:3

Explanation: In Bell and spigot joint, the ratio of cement and mortar used is 1:1 in the space provided between bell and spigot end.

3. The ratio of cement mortar used in the Collar joint is?
a) 1:2
b) 1:6
c) 2:1
d) 1:1

Explanation: In the Collar joint, the ratio of cement and mortar used is 1:1 in the space provided between the collar and the ends of the pipe.

4. Which joint in the sewer is known as ring tie coupling?
a) Bell and spigot joint
b) Collar joint
c) Mechanical joint
d) Simplex joint

Explanation: In Simplex joint, coupling of asbestos cement pipe and two rubber ring takes place, so this joint is called as ring tie coupling.

5. In which sewer joint, bituminous compounds are added?
a) Collar joint
b) Flexible joint
c) Mechanical joint
d) Simplex joint

Explanation: When cement mortar is added in the joints of sewer, they get easily cracked, so bituminous compound is added to overcome this problem and the joint is called as Flexible or Bituminous joint.

6. The type of joint used for metallic sewer is __________
a) Collar joint
b) Flexible joint
c) Mechanical joint
d) Simplex joint

Explanation: Mechanical joints are used in metallic sewer where mechanical devices like flagged rings and bolts are used.

7. Semi elliptical sections of sewer are not used nowadays.
a) True
b) False

Explanation: There is no availability of factory made sections of this shape and its construction is also difficult.

8. _______ columns are used for the ventilation of sewer.
a) Aeration columns
b) Inclined columns
c) Ventilating columns
d) Vertical columns

Explanation: Ventilating columns are used for the ventilation of sewer. They keep the air inside the sewer pipe at atmospheric pressure.

9. The diameter of the sewer is _____ the diameter of ventilating column.
a) Equal to
b) 2 times
c) 3 times
d) 4 times

Explanation: The diameter of ventilating column is one third of the diameter of the sewer. They can be provided when there is a change in size of sewer.

10. Ventilating columns are provided at intervals of ______ along the sewer lines.
a) 30m
b) 50m
c) 100m
d) 150m

Explanation: The ventilating columns can be provided at the upper end of branch sewer at intervals of 150m to 300m along the sewer lines.

11. _______ is used to remove the waste directly from the building.
a) Branch sewer pipe
b) Outfall sewer pipe
c) Soil vent pipe
d) Main sewer pipe

Explanation: Soil vent pipe is used to remove the waste from toilets, sinks, bathrooms and rain water. It is placed on the exterior of the building.

12. Which of the following is called as a ventilated discharge pipe?
a) Branch sewer pipe
b) Soil vent pipe
c) Outfall sewer pipe
d) Main sewer pipe

Explanation: Soil vent pipe is called as ventilated discharge pipe and they help in the removal of foul smell from the sewage.

13. Which gas among the following is not produced in the sewer?
a) H2S
b) HCL
c) CO2
d) CH4

Explanation: HCL is not produced in the sewer. H2S, CO2 and CH4 are produced in a sewer which is more effective when the sewage is septic.

Sanfoundry Global Education & Learning Series – Environmental Engineering.

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