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 1 of 3.
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).
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.
Aman gautam said:
1 decade ago
@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.
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.
Akash said:
10 years ago
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:
10 years ago
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.
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.
Ujjwal mondal said:
7 years ago
Dia of sewer ------- Gradient ------ Velocity.
100 ------- 1 in 60 ------- 0.58 m/s.
150 ------- 1 in 100 ------- 0.61 m/s.
225 ------- 1 in 120 ------- 0.79 m/s.
100 ------- 1 in 60 ------- 0.58 m/s.
150 ------- 1 in 100 ------- 0.61 m/s.
225 ------- 1 in 120 ------- 0.79 m/s.
(6)
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.
Sashank said:
5 years ago
Assume,
Self cleansing Velocity(V) = 0.9 m/s.
n=0.015,
and R=D/4.
then, V=1/n * (R)^(2/3) * (S)^(1/2).
On solving, S = 120.
Self cleansing Velocity(V) = 0.9 m/s.
n=0.015,
and R=D/4.
then, V=1/n * (R)^(2/3) * (S)^(1/2).
On solving, S = 120.
(18)
Ritesh Dev Singh said:
9 years ago
By Shield's Theory,
Self - cleansing velocity (Vs),
Vs= √ {8kgd'(G-1)}÷f], where,
k= (1-n)sin θ.
Self - cleansing velocity (Vs),
Vs= √ {8kgd'(G-1)}÷f], where,
k= (1-n)sin θ.
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