- #1
Struggling
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Hi,
Im currently doing an assignment where i have to design a water reticulating system for a small suburb.
I have planned out all my distribution mains and my reticulation mains and services
I also have the water demand(Q) for the houses using the Australian Standards for plumbing and drainage.
So i know my Q value from Australian standards given by the formula:
Q=3.637*10^-5 H^0.555 D^2.667
where:
Q=Flow rate (L/s)
D=pipe diameter
H=head loss gradient in meters per 100m given by: (h*100)/(L*1.5) where h= Head loss in meters head, L= index length in meters and 1.5 is a factor allowing additional head loss through fittings
So for example (this is the calcs i did on one of the reticulation mains with a dead end serving 3 houses)
If i have
Q=1.03 L/s
L=50 M
h=1.1
1.03=3.637*10^-5 * 1.46^0.555 * D^2.667
D = 43.16 mm
now using this with V=Q/A i get V to be V=0.709 m/s
Am i doing this right? because the velocity seems to be very slow(even though the maximum allowable is 3m/s anyway)
and am i going about it the right way? i thought start from the demands from the houses and work backwards to the distribution mains that way i can calculate all the pressures,velocities and flows needed at the entrances of the reticulation mains.
and if this is right, what formula do i use to work out the pressure needed to at the entrance of this pipe to supply this flow and velocity? I've been reading fluid mechanics books all week and i can't seem to crack it.
Thanks in advance
Im currently doing an assignment where i have to design a water reticulating system for a small suburb.
I have planned out all my distribution mains and my reticulation mains and services
I also have the water demand(Q) for the houses using the Australian Standards for plumbing and drainage.
So i know my Q value from Australian standards given by the formula:
Q=3.637*10^-5 H^0.555 D^2.667
where:
Q=Flow rate (L/s)
D=pipe diameter
H=head loss gradient in meters per 100m given by: (h*100)/(L*1.5) where h= Head loss in meters head, L= index length in meters and 1.5 is a factor allowing additional head loss through fittings
So for example (this is the calcs i did on one of the reticulation mains with a dead end serving 3 houses)
If i have
Q=1.03 L/s
L=50 M
h=1.1
1.03=3.637*10^-5 * 1.46^0.555 * D^2.667
D = 43.16 mm
now using this with V=Q/A i get V to be V=0.709 m/s
Am i doing this right? because the velocity seems to be very slow(even though the maximum allowable is 3m/s anyway)
and am i going about it the right way? i thought start from the demands from the houses and work backwards to the distribution mains that way i can calculate all the pressures,velocities and flows needed at the entrances of the reticulation mains.
and if this is right, what formula do i use to work out the pressure needed to at the entrance of this pipe to supply this flow and velocity? I've been reading fluid mechanics books all week and i can't seem to crack it.
Thanks in advance