Pump Sizing and Flow Rate Calculation in Construction Technology
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Added on  2023/06/04
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This article discusses the process of sizing a pump in construction technology, including factors such as flow rate, total differential head, static head difference, and frictional head losses. It also covers the calculation of flow rate and head pressure for an apartment building. The article includes relevant formulas and calculations.
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CONSTRUCTION TECHNOLOGY 6 By Name Course Instructor Institution Location Date
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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
Type of fluid=water Phase of the fluid=liquid Flow rate=30000kg/hr. Liquid density=998kg/m3 Water viscosity=1cP Vapor pressure=0.023bar Gas pressure vessels Suction gas pressure=1bar Gas pressure of discharge=2bar Static heads Static head at suction=2m Static head at discharge=120m Pipelines Nominal diameter pipe=4(suction line) and 3(discharge line). Pipe schedule=40(for both suction line and discharge line) Length of the pipe=150m (discharge line) and 10m for suction line. Absolute roughness=0.046m for both suction and discharge line.
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Fittings 90 degrees LR bends=1(suction line) and 4(discharge line),Pipe entrances=1(suction line) and 0 for discharge line. Gate valves=1(discharge) and also 1(suction line),Swing check valve=1(suction line). Fitting factor=1 for both suction and discharge line (Nikaido and Pagès 2012). Discharge lineLine of suction Relative roughness0.000440.00058 Area of flow0.008200.00476 Velocity Reynolds number 1.03 103757 1.76 136173 Regime of flowTurbulentTurbulent Factor of friction0.02110.0202 Velocity loss factor1.96737.43 Total velocity head loss `1.7252.024 Frictional pressure loss 0.030.61 Frictional head loss=0.186.35 Suction pressure of the pump=2.18bar Sanction head=22.36m Discharge pressure of the pump=15.34bar Discharge head pump=156.67m Pump overall differential pressure (mH) =13.18bar
Differential head=134.85m Pump power=15.56Kw Pump flow rate (Q) =31m3/hr. PART C Calculation of flow rate, it may be assumed that the apartment has 56 units; 18 floors, residual pressure of 30psi, supply pressure by council is equal to 30psi, two full bath taps and dish washer machine at each unit. Bathtubs: 4*112 tubs=448fu Sink: 1*112=112fu Toilet: 2.4fixture*112=280fu Kitchen sink: 1.5*56=84fu Clothes washer:1.5*56washer=84fu,the total fixture units sum 1092 and this gives flow rate of 220gpm.The flow rate=220gpm(Yannopoulos et al 2015). Calculation of head In this calculation, the following elements must be considered; friction head, residual head pressure, static head and finally inlet head pressure. Static head= (18*12 feet per floor) =216 feet but 1psi=2.31 feet of head. This follows that total pressure is calculated as
216feet/2.30=93.49 Approximately 94 psi. Calculation of friction loss This is affected by pipe diameter, distance and gpm =216 feet+100feet =316feet Taking into account elbows and other fittings, the loss factor is 0.5 =316 feet*0.05 =16feet,friction loss increases with increase in gpm. Total equivalent pipe length =316feet +16feet =332feet (332feet*6feet)/100feet=20feet. HF=20feet/2.31 =8.7Psi Residual pressure head,HR=30psi. The required discharge pressure=94psi+9psi+30psi mH =133psi
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REFERENCES Nikaido, H. and Pagès, J.M., 2012. Broad-specificity efflux pumps and their role in multidrug resistance of Gram-negative bacteria.FEMS microbiology reviews,36(2), pp.340-363. Monteith, G.R., Davis, F.M. and Roberts-Thomson, S.J., 2012. Calcium channels and pumps in cancer: changes and consequences.Journal of Biological Chemistry,287(38), pp.31666-31673. Sun, J., Deng, Z. and Yan, A., 2014. Bacterial multidrug efflux pumps: mechanisms, physiology and pharmacological exploitations.Biochemical and biophysical research communications,453(2), pp.254-267. Yannopoulos, S.I., Lyberatos, G., Theodossiou, N., Li, W., Valipour, M., Tamburrino, A. and Angelakis, A.N., 2015. Evolution of water lifting devices (pumps) over the centuries worldwide.Water,7(9), pp.5031-5060.