Pump Sizing and Flow Rate Calculation in Construction Technology

CONSTRUCTION TECHNOLOGY 6
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PART (B)
Pump sizing. `
In the process of sizing a pump, the following points must be given specific consideration;
Flow rate
This is normally obtained by the process through which the pump is installed. The mass and
energy balance of the process ultimately define the process.
Total differential head
Total differential head=Frictional head losses differences of static head.
Static head difference
It is the difference in the head between the suction static head and discharge static head; static
head difference=suction static head+discharge static head.
Static head
This is normally considered as the sum of the gas pressure at the liquid surface in the vessel of
discharge(Monteith et al 2012).
Frictional head losses
Frictional head losses consist of frictional losses in the piping system of the suction part and also
in the discharge piping system.
This is normally calculated using the formula below;

Frictional head losses= (FL/D+Kfittings) u2/2g where;
F=friction factor
L= pipe length
D=diameter of pipe
K=fitting factor
U=velocity of the liquid
g=acceleration due to gravity.
Pump power
Pump power=flow rate*density of the liquid*acceleration due to gravity*efficiency of the
pump*total differential.
Assuming that the amount of water to be pumped is 30000kg/hr. from one tank to another, water
temperature is at 20c,density of 998kg/m3,vapour pressure of 0.023 bar and a viscosity of
1cp.The efficiency of the pump is taken to be 70%( Sun, Deng and Yan 2014).
Details of the pump
Barometric pressure=1.013bar
Margin available=0m
Efficiency of the pump=70%
Properties of the fluid