What is the optimum Design margin for Drv HP for pump motor
What is the optimum Design margin for Drv HP for pump motor
(OP)
Hi,
Can any one let me know, what is the optimum design margin must be take in account during design phase for a pump beyond the suction and design head requirements.If some one have practical experience and hand on best margin please share with me or if have reading material please post it here.
Thanks
MIANCH
Can any one let me know, what is the optimum design margin must be take in account during design phase for a pump beyond the suction and design head requirements.If some one have practical experience and hand on best margin please share with me or if have reading material please post it here.
Thanks
MIANCH





RE: What is the optimum Design margin for Drv HP for pump motor
RE: What is the optimum Design margin for Drv HP for pump motor
RE: What is the optimum Design margin for Drv HP for pump motor
Thank you for your input, we have bad experience with 10% margin, Pump is not able to pump design flow and taking hi amps.
Pump was designed for 70m^3/hr but now pumping less than 50m^3/hr.
I have done all calculation and finally come to this point may be Driver have less capcity.
Thanks
MIANCH
RE: What is the optimum Design margin for Drv HP for pump motor
10% is reasonable, sometimes more is used but usually only when standard size motors are not convenient for closer matching to the actual required power.
I would imagine that you have some other problem.
RE: What is the optimum Design margin for Drv HP for pump motor
RE: What is the optimum Design margin for Drv HP for pump motor
RE: What is the optimum Design margin for Drv HP for pump motor
Capacity Normal/ Rated m3/hr= 72.8/80
Suction pr. Max/ Rated barg= 4.3/ 2.08
Discharge Pressure barg= 8.21
Differential Pressure barg= 6.13
Diff Head "m"= 108
suction Head "m" @ top of FND= 4.3
Pumping Temperature "0C"= 228
Vap Pressure barg= 2.8
Sp Gr= 0.58
Viscosity= 0.15
Imp Dia, Rat/MAX/MINI "mm"= 297/350/280
Rated Power Kw= 23
Efficiency %= 59
Minimuim Continuous Flow m3/hr= 20/ 30
Allowable operating range m3/hr= 30-120
Max Head @ rated imp m3/hr= 122
Max power @ rated imp Kw= 26.7
NPSHR @ rat Capacity @ TOF "m"= 3
NPSHR @ rat Capacity @ Impeller center "m"= 2.65
Suction Specific Speed "GPM.ft"= 10690
Suction Nozzal Ø inches= 4
Discharge Nozzal Ø= 3
I have found one difference in viscosity, in design they used 0.15cp and Distillate have 0.38cp (Distillate IBP /FBP is 145/ 316C) and SP Gr is 0.785.
Hope you will come up with good results.
Thanks
MIANCH
RE: What is the optimum Design margin for Drv HP for pump motor
If it were my pump, I would make sure the motor was at least 37 kW for this installation.
RE: What is the optimum Design margin for Drv HP for pump motor
RE: What is the optimum Design margin for Drv HP for pump motor
Can you please post some calculation method.
Thanks
MIANCH
RE: What is the optimum Design margin for Drv HP for pump motor
Back to your original question - "what is the optimum design margin must be take in account during design phase" -motor size for at the design stage should be, end of curve requirement + 20% or the closest standard motor available.