Calculating Gross Efficiency for a Water Pump

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Jan Mashele Participant Join Date: Aug 2008 Posts: 1	Calculating Gross Efficiency for a Water Pump 08/19/2008 8:19 AM
	Please help me calculate the gross efficiency of pump when forcing cold water through the system. Total static lift 14.15m static suction lift 2.05m Discharge 0.1m3/s Power input 22kw Total length of suction pipe 8.5m Total length of discharge pipe 47.5m Diameter of suction pipe 250mm Diameter of discharge pipe 200mm Assume f=0.006 K foot valve 2 K bend 0.25
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Anonymous Poster	#1 Re: Calculating Gross Efficiency for a Water Pump 08/19/2008 10:45 PM
	How about the easy way? Have a look at the pump performance curve. And if you don't have it - go your supplier/manufacturer.
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JoeWong Active Contributor Join Date: Apr 2007 Posts: 12 Good Answers: 1	#2 Re: Calculating Gross Efficiency for a Water Pump 08/20/2008 12:28 AM
	Jan Mashele, As highlighted by "Guest", you may obtain the pump efficiency from pump curve dedicated to your pump... When we talk about pump, the first thing is the type. Centrifugal ? Reciprocating ? The efficiency could be very different. Pump efficiency for Reciprocating pump could be as high as 80-85% Pump efficiency for centrifugal pump may vary from 40-80% (even lower but not cost effective). During design phase, for centrifugal pump, the following methods may be consider : Pump Efficiency Estimation Without Vendor Information Estimate Pump Efficiency base on Specific Speed (Ns)
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PWSlack Guru Join Date: Jan 2007 Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on. Posts: 32175 Good Answers: 839	#3 Re: Calculating Gross Efficiency for a Water Pump 08/20/2008 5:05 AM
	Total lift = 16.2m Assume density = 1000kg/m³ and gravity = 9.81ms^-2 Pressure change = 16.2m x 1000kg/m³ x 9.81ms^-2= 1.59e5 N/m² System work = 1.59e5N/m² x 0.1m³/s = 1.59e4 Watts Input power = 2.2e4 Watts Therefore system efficiency = 1.59e4/2.2e4 = 72% or so. Ready for the next time? __________________ "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
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Anonymous Poster (1); JoeWong (1); PWSlack (1)

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