Civil Engineering - Waste Water Engineering - Discussion
Discussion Forum : Waste Water Engineering - Section 1 (Q.No. 6)
6.
If the diameter of sewer is 225 mm, the gradient required for generating self cleansing velocity, is
Discussion:
29 comments Page 2 of 3.
Dharmesh said:
5 years ago
Thank you @Ujjwal Mondal.
Shree said:
6 years ago
Thanks all for explaining it.
Praveen M N said:
6 years ago
NBO recommend for small sewers.
225 dia = 1:120 = 0.79 m/sec.
225 dia = 1:120 = 0.79 m/sec.
Deepak said:
7 years ago
National building organization (N.B.O) of India has suggested as for 100mm, 150mm, 225mm dia the gradient required to generate self-cleaning velocity are 1in60, 1 in 100, 1 in 120 respectively.
Haris said:
7 years ago
I did not get it please explain.
Sandip ghosh said:
1 decade ago
But actually 1 in 105 for a velocity of 0.9m/s & 1 in 150 for a velocity of 0.75m/s.
Raaj said:
7 years ago
Thank you all for giving the answer.
Gubendhiran said:
8 years ago
Using Manning's formula.
Vs=[(R^0.67)*(S^0.5)]/n.
For circular sewer R=D/4=0.225/4=0.05625m.
Vs=ranges from 0.45 to 0.8 m/s from S.K.GARG EEN Vol IIT.
Take Max for design Vs=0.8 m/s.
n=Manning's constant=0.015.
0.8=[(0.05625^0.67)*(S^0.5)]/0.015.
(S^0.5)=0.08253.
S=0.00681.
S=1/147.
So we can option 'C'.
Vs=[(R^0.67)*(S^0.5)]/n.
For circular sewer R=D/4=0.225/4=0.05625m.
Vs=ranges from 0.45 to 0.8 m/s from S.K.GARG EEN Vol IIT.
Take Max for design Vs=0.8 m/s.
n=Manning's constant=0.015.
0.8=[(0.05625^0.67)*(S^0.5)]/0.015.
(S^0.5)=0.08253.
S=0.00681.
S=1/147.
So we can option 'C'.
Dheeraj singh said:
8 years ago
The slope of sewer should be designed for min permissible velocity at min flow but in this case, a material made of sewer not given so can't be calculated if I assume brick-lined sewer then calculate slope by given velocity trial and error velocity (1to2.5).
Sanjay said:
8 years ago
Self cleaning velocity is 0.75 m/s to 0.9 m/s.
So 100/120 =0.83.
100/60 =1.66.
100/100 =1.
So right answer is 1 in 120.
So 100/120 =0.83.
100/60 =1.66.
100/100 =1.
So right answer is 1 in 120.
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