# Civil Engineering - Waste Water Engineering - Discussion

@ : Home > Civil Engineering > Waste Water Engineering > Section 1 - Discussion

"I never see what has been done; I only see what remains to be done."
- Marie Curie
6.

If the diameter of sewer is 225 mm, the gradient required for generating self cleansing velocity, is

 [A]. 1 in 60 [B]. 1 in 100 [C]. 1 in 120 [D]. none of these.

Explanation:

No answer description available for this question.

 Sandip Ghosh said: (Tue, Dec 9, 2014 05:14:21 PM) But actually 1 in 105 for a velocity of 0.9m/s & 1 in 150 for a velocity of 0.75m/s.

 Aman Gautam said: (Wed, Dec 10, 2014 07:52:36 PM) @Sandeep. Greater is the gradient, greater is the velocity. Thus your point is wrong and as for 225 mm diameter, velocity should be 1 m/s. So it would require the highest gradient.

 Manohar said: (Thu, Jul 9, 2015 05:06:58 PM) Yes, the gradient, 1 in 105 is greater than 1 in 150.

 Ganesh said: (Thu, Oct 29, 2015 07:35:15 PM) Which formula is used here to calculate self cleansing formula?

 Akash said: (Sat, Dec 26, 2015 05:31:39 PM) V-under root (8 beta under f multiply by (specific gravity of solids- 1)*g*diameter of solids). Find v and using manning or any other formula find slope. But data is not sufficient.

 Narayan said: (Sun, Jan 17, 2016 09:52:20 AM) Velocity of the sewer is 0.9 to 0.75 m^3/s. So assume velocity of sewer V = 0.9 m/s. And using the manning's formula: V = R^2/3*s^1/2/n but the wastage flow is not specify.