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1. Quantitly of delivery : (m3/min,m3/hr,Ton/day,G.P.M)
The allowance,10~20% of required
quantity,is recomme-nded to keep.
2. Diameter : it should
be determined as economically as possidle. For its standard,refer
to
Dia-meter of suction and range of water puan
3. Total Head : Total Head(M,Ft)
shall be determined as follows.
pump head is the vertical height to which the pump can pump
up the water
and Total Head is determined by ad-ding to the actual vertical
height.another vertical height to which the losses due to length
and diameter of the pipe are converted. Meanwhile it is not
easy to convert the
lost head to a vertical height,and moreover this head may vary
with length and doamenter of the pipe, flowrate, conditions
of the pipe, and temperature of water, if the head is determined
too hogh,
the pump will not only be an unnecessarily high pressure pump,
but also can be operated in a lower pressure actually, As a
result there may occur a lower of overload even though water
os delivered much enough, On the contrary, if the head is determined
too low, Water will not be delivered any more or be,
if any, deliverd only a little.Therefore it is veru important
to determine the lost head appropriately. |
Total Head(Ht)= A.(Hs) Actual Head of Suction
+B.(Hd) Aceural Head of Delivery
+C.(Hv) Head of Flow Velocity
+D.(Hf)
Head of Friction
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A. Actual of suction(m) : The vertical height from the center
line of pipe's suction opening of the
suction water level
B. Actual Head of Delivery(m) : The vertical height from the
center line of pip's suction opening
of the pipe to the highest water level of the water tank
C. Head of Flow Velocity(m) : This is derived from the difference of diameter between suction pipe and
delivery pipe. But this value is O if both the diameters are equal,
and is small enough to ignore if any difference.
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Hv=vd2-Vs2
2g
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D. Head of Friction
Loss(m) : There are several calculation methods,the most popular one of which,
Darcy formula,is introduced as below. |
※Calculation
Method of Friction Loss Head(Darcy Formula)
Hf(m)=f.
f : Friction loss coefficient df pipe(0.020+0.0005/D)New pipe.Old
pipe=0.04
D: Diameter of pipe(m)
L: Length of pipe(m)
V: Flow velocity of pipe(m/sec)
g: Gravitational acceleration : 9.81m/sec2
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