HP Consumed by a Hydraulic Pump

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Anonymous Poster #1	HP Consumed by a Hydraulic Pump 02/06/2015 2:26 PM
	I am wondering how to add HP of Hydraulic Pumps. If I have a pump and I wanted to calculate the HP needed to do the work required I would use this equation. Horsepower input = GPMPSI/(1714 overall Eff)= HP If I have a tandem pump ( two outlets and two inlets same shaft) one section at .714 CID (350 PSI 2800 rpm) and the other section at .144 CID (2000 PSI 2800 RPM). what would the pump HP needed? Based on the equations: .714 CID ==> 8.6 GPM (2800 RPM) .144 CID ==> 1.74 GPM (2800RPM) .714 HP ==> (8.6 GPM)(350 PSI)/(1714 * .85 eff)= 2.06 HP Assuming 85 % eff on Gear pump .144 HP ==> (1.74 GPM)(2000PSI)/(1714*.85 eff)= 2.388 HP Assuming 85 % eff on Gear pump Can I add the HPS and say that the over all HP needed by the pump it is 4.448 HP? this is being driven by a pulley that it is also running another tandem pump 18GPM at 4350 PSI assuming 95 % eff (piston pump eff) Main Piston Pump input HP = 53.7 HP Can I say that my overall input HP required from the Gas Engine is 58.192 HP? Thanks.
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Fredski Guru Join Date: Feb 2011 Posts: 7025 Good Answers: 207	#1 Re: HP Consumed by a Hydraulic Pump 02/06/2015 4:41 PM
	ANONS
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Anonymous Poster #2	#2 Re: HP Consumed by a Hydraulic Pump 02/06/2015 6:15 PM
	Yes.
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delreer Associate Join Date: Jan 2015 Posts: 26	#5 In reply to #2 Re: HP Consumed by a Hydraulic Pump 02/06/2015 7:18 PM
	If this is the case can you explain smothering for me really quick. Since we have the tandem pumps that draw the 2 and 2 and change HP and we can add it. Why on the piston tandem pump (even though both sections have the same PSI rating and GPM) we don't add their HP consumption to get us to 98 ish HP? 4 and change from the barge pumps (gear pumps) + 48 ish peri section of the piston pump ?? This is been bugging me because my engine it is rated to 55 HP and yet it doesn't stall when I run the tandem piston pumps and the gear charge pumps...
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lyn Guru Join Date: Oct 2008 Posts: 42355 Good Answers: 1693	#3 Re: HP Consumed by a Hydraulic Pump 02/06/2015 6:32 PM
	Hydraulic Pump Rating and Selection Factor.
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delreer Associate Join Date: Jan 2015 Posts: 26	#4 In reply to #3 Re: HP Consumed by a Hydraulic Pump 02/06/2015 7:14 PM
	Lyn, Thanks for the help but they don't cover HP (or at least I did not see it)
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Kulas Power-User Join Date: Dec 2014 Posts: 418 Good Answers: 3	#6 Re: HP Consumed by a Hydraulic Pump 02/06/2015 9:21 PM
	Get a multimeter, get actual voltage, current and power factor reading when pumps are operating at full whaam. Actual HP is the actual demand and spent. __________________ "When I thought I exceeded to be wise but wisdom was far from me" -King Solomon
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lyn Guru Join Date: Oct 2008 Posts: 42355 Good Answers: 1693	#7 Re: HP Consumed by a Hydraulic Pump 02/07/2015 9:41 PM
	What did the pump maker say? Or, is this homework?
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Oliver Dunthorne Power-User Join Date: Nov 2008 Posts: 116 Good Answers: 4	#8 Re: HP Consumed by a Hydraulic Pump 02/08/2015 9:32 AM
	Hi You can add the HP's but your efficiency figures are pie in the sky. Your best piston units might be 95% volumetrically efficient but overall efficiency will be (95% V x 95% Mech. = 90%) at best !! So be safe and go with a figure of 85% efficient and you units will run. Get it wrong and the prime mover will be in trouble and either stall or overheat dependent on what it is. Remember the output from IC engines varies from hot to cold and atmospheric changes plus wear and tear so always have something in hand. Oliver Dunthorne - Hydraulic Engineer - Retired
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Anonymous Poster (1); delreer (2); Fredski (1); Kulas (1); lyn (2); Oliver Dunthorne (1)

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