eco_dia
TRANSCRIPT
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JAKHAPUPR L. I .S
ECONOMICAL DIAMETER FOR RISING MAIN
DATA
1 Total discharge in cum/sec = 0.64
2 No of rows of rising main No. = 1
3 Length of rising main in m. = 1300
4 Static head for pump in m (HSP 66.50F.S.L. IN DC = 721.3
5 Hf. IN pump assembly = 0.67POL. = 654.80
(1% of Hsp)
6 static head for rising main (HSR 26.3C.L of rising main = 695
7 No of pumps = 2
8 Discharge per pump in cum/sec 0.319Cr = Roughnes coefficient of pipe = 1
9 Pump efficiency = 0.9
Head for rising main Pipe shell thickness mm
1 2 3 4 5 6 7 8 9 10 11 12 13 14
1 0.55 1 0.64 2.00 2.68 26.3 10.25 11.27 150.34 187.92 3.31 3.10 2.95 8
2 0.60 1 0.64 2.00 2.25 26.3 6.74 7.42 129.71 163.43 3.15 3.38 3.09 10
3 0.65 1 0.64 2.00 1.92 26.3 4.59 5.05 108.85 140.20 2.92 3.66 3.23 10
4 0.70 1 0.64 2.00 1.66 26.3 3.21 3.53 92.48 122.31 2.74 3.94 3.38 10
5 0.75 1 0.64 2.00 1.44 26.3 2.31 2.54 79.41 108.24 2.60 4.23 3.52 10
Sr.No.
Dia.ofrisingmain
No.ofrows
Dischargeper row
No.ofpumps
Velocityin m/sec
Statichead in
m.
Frictionhead Hf
in m.
Totalfrictionhead =
1.1*Hf m.
50% ofwater
hammerhed in m.
Design head=
col.7+9+10
T1 forinternalpositivepressure
as per I.S.5822-1994
T2 forexternalnegativepressureas per
I.S.5822-1994
T3 forhandlingpoint ofview asper I.S.4480
(part-7)-1975
(Cl.5.1.1)
T4minim
as petable -3I.S. 35
199
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CALCULATIONS FOR H.P
The speiman calculations for optimization study
Data
1 Total discharge = Q cum/sec 0.64
2 No. of working pumps = No. 2
3 Discharge per pump = q cum/sec 0.3194 Total No. of rising main = No. 1
5 Discharge of rising main per row = Q1 cum/sec 0.64
6 Diameter of rising main = D m 0.65
cm 65
mm 650
7 length of rising main = L m 1300
8 Velocity through rising main = V m/sec 1.920
< 2.1 m/sec
Permissible velocity
9 Details of source.
9.1 M.D.D.L. m 653.0189.2 F.S.L. m 655.668
9.3 H.F.L. FRL m 655.67
9.4 P.O.L. POL m 654.790
9.5 F.S.L. in delivery chamber FSLD m 721.300
9.6 Centre line of celivery pipe CLD m 695.000
9.6 thiclness of rising main t mm 6
cm 0.6
m 0.01
Calculations
a) Static head for rising main = HSR
FSLD - CLD = m 26.300
b) Static head for pumping = HSP
FSLD - POL = m 66.510
c) Frictional head loss ithe rising main by Modified Hazen William's formula
Hf = ((L*(Q1/Cr)^1.81)/(994.62*D^4.81)
Where
L = Length of rising main = m 1300
Q = Discharge of R.M./row = cum/sec 0.64
Cr = Roughness coefficient = 1
( as per Water Supply Manual & Treatment)
D = Diameter of rising main = m 0.65
Now Hf = m 4.5884
Assume losses in bends,elbows,tee etc
10% of Hf m 0.459
Total head loss in R.M. Hft = m 5.047
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d) Water Hammer pressure in the rising main.
Maximum water hammer pressure
WHP =C*(Vo/g)
Where
C = wave velocity
g = gravitional acceleration m/sq sec 9.81
Vo = velocity in rising main m/sec 1.920
C = 1425/sqrt(1+K*(D/t))
Modulus of Elasticity of pipe material
Bulk Moeulus Of Elasticity of water = Kg/sqcm ###
Modulus of Elasticity of pipe material Kg/sqcm ###
K = 0.01
D = m 0.65
t = m 0.01
C = m/sec 990.96
WHP = m 193.91
For design purpose 50% of WHP is considered
Design WHP = m 96.957
e) Design pressure head
e-1) Working pressure head = Wp
HSR +Hft = m 31.347
e-2) Design pressure head = Wd =
Wp + Design WHP = m 128.304
Kg/secm 12.830
f) Thickness of rising main.
f-1) T1 thickness for internal positive pressure as per I.S.-5822-1994
T1 =((P*D/((2*a*f*e)+p))*1.125*10 mm
WhereP = Design pressure = Kg/sqcm 12.830
D = Outer Dia. Of pipe = cm 66.2
a = design factor = 0.9
when surge pressure is considered
f = Specified yield stress= Kg/sqcm 2500
(from I.S.-2062-1992 table-2)
e = weld efficiency = 0.8
(for field welding)
mm 2.645
K = Bulk Moeulus Of Elasticity of water
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Now T1 =
f-2) T2 thickness for -ve (vaccume) pressure as per I.S.- 5822-1994
clause B-3.1
(1-y^2)
Where
pcr = vaccume pressure = 1/3 of atmospheric pressure +Over brden of 1.2m
vaccume pressure = Kg/sqcm 0.33
Over burden Wt of soil = 1.2*0.208 Kg/sqcm 0.25
(0.208 = saturated wt. of soilin kg/sqcm)
total pcr= 0.58
E Young's modulus of pipe material = Kg/sqcm 2100000
Y = Poission's ratio = 0.3
D = internal Dia = cm 65
Now T2 = mm 3.663
f-3) Thickness from handling point of view as per I.S.-4880-(part-7)-1975
Clause 5.1.1
t = ((D+50)/400)*10*1.125
Where
D = diameter of pipe in cm = cm 65
Now T3= mm 3.234
f-4) Minimum thickness as per I.S.-3589-1991
(As per table 3)
T4 = mm 6
Maximum of T1, T2, T3, T4 = mm 6
Consider corrosion allowance mm 0
(as Dia. Of rising main is less than 1000)
Thickness provided = mm 6
However provide the thickness mm 10
h) pumping capacity
Hp required =( w*Q*H)/75*)Where
w = unit wt of water = Kg/cum 1000
Q = total discharge = cum/sec 0.64
H = total head =
HSP + pump assembly losses + Hft
Pump assembly losses = 1% of static head
for pumping = m 0.67
H = total head = m 72.222
= Pump efficiency = 0.9
pcr = (2*E*(t/D)^3)*1.125*10
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HP Required = Hp 749.722
HP provided= 740
No. of pumps provided = 2
Hp per pump = 370