# Civil Engineering - Waste Water Engineering - Discussion

Discussion Forum : Waste Water Engineering - Section 1 (Q.No. 37)
37.
For non-scouring velocity 5 m/sec, the type of sewers generally preferred to, is
cast iron sewers
cement concrete sewers
glazed bricks sewers
stone ware sewers.
Explanation:
No answer description is available. Let's discuss.
Discussion:
6 comments Page 1 of 1.

Gnani said:   2 years ago
For the house purpose, we used this glazed brick sewer the velocity is also small like 5m/s. So, C is the correct answer.

Pankaj dubey said:   3 years ago
The interior surface of the sewer pipe gets scored due to the continuous abrasion caused by suspended solids present in sewage. The scoring is pronounced at higher velocity than what can be tolerated by the pipe materials. This wear and tear of the sewer pipes will reduce the life span of the pipe and their carrying capacity. In order to avoid this, it is necessary to limit the maximum velocity that will be produced in sewer pipe at any time. This limiting or non-scouring velocity mainly depends upon the material of sewer. The limiting velocity for different sewer material is provided in Table 7.2. Table 7.2 Limiting or non-scouring velocity for different sewer material. Sewer Material Limiting velocity, m/sec Vitrified tiles 4.5 - 5.5 Cast iron sewer 3.5 - 4.5 Cement concrete 2.5 - 3.0 Stoneware sewer 3.0 - 4.5 Brick lined sewer 1.5 - 2.5.

The problem of maximum or non-scouring velocity is severe in hilly areas where the ground slope is very steep and this is overcome by constructing drop manholes at suitable places along the length of the sewer. 7.8 Effect of Flow Variations on Velocities in a Sewer The discharge flowing through sewers varies considerably from time to time. Hence, it occurs variation in depth of flow and thus, variation in Hydraulic Mean Depth (H.M.D.). Due to change in H.M.D. there occur changes in flow velocity, because it is proportional to (H.M.D.)2/3. Therefore, it is necessary to check the sewer for minimum velocity of about 0.45 m/sec at the time of minimum flow (1/3 of average flow) and the velocity of about 0.9 to 1.2 m/sec should be developed at a time of average flow. The velocity should also be checked for limiting velocity i.e. non-scouring velocity at the maximum discharge.

Rajeshkumar J said:   5 years ago
@Sourav.

Garry said:   5 years ago
Vitrified clay or stoneware or salt glazed sewer is the same thing.

So, the answer is a stoneware sewer.

Sourav said:   6 years ago
Sewer Material Limiting velocity, m/sec.

Vitrified tiles 4.5 " 5.5.
Cast iron sewer 3.5 " 4.5.
Cement concrete 2.5 " 3.0.
Stone ware sewer 3.0 " 4.5.
Brick lined sewer 1.5 " 2.5.

Ratna kumar said:   6 years ago