Can you reduce gpm this way?

   / Can you reduce gpm this way? #1  

desert trader

Member
Joined
Jan 24, 2010
Messages
27
Location
Shoshone,Idaho
Tractor
Massey Ferguson 165
I came across a 540 rpm hydraulic pto gear pump that had been reduced at the inlet from 1 1/2" to1" and reduced at the outlet from 1 1/2" to 3/4" and I guess they were trying to reduce the gpm.
My question is can you reduce the gpm this way without causing some sort of
problem?
I'm reposting this because if this won't work I'm not going to use this pump.
Your input will be greatly appreciated.
 
   / Can you reduce gpm this way? #2  
It may work if the inlet and outlet are sized correctly.

The normal method would be to run a line from discharge to suction with an adjustable valve. :D
 
   / Can you reduce gpm this way? #3  
I came across a 540 rpm hydraulic pto gear pump that had been reduced at the inlet from 1 1/2" to1" and reduced at the outlet from 1 1/2" to 3/4" and I guess they were trying to reduce the gpm.
My question is can you reduce the gpm this way without causing some sort of
problem?
I'm reposting this because if this won't work I'm not going to use this pump.
Your input will be greatly appreciated.

You can use a valve like this, and vary the GPM from 0 to 16 GPM's.

https://www.surpluscenter.com/item.asp?UID=3240031516455707&item=9-4169-10&catname=hydraulic

https://www.surpluscenter.com/item.asp?UID=3240031516455707&item=9-5223&catname=hydraulic

Make sure you have a relief valve for the pump.
 
Last edited:
   / Can you reduce gpm this way? #4  
I came across a 540 rpm hydraulic pto gear pump that had been reduced at the inlet from 1 1/2" to1" and reduced at the outlet from 1 1/2" to 3/4" and I guess they were trying to reduce the gpm.
My question is can you reduce the gpm this way without causing some sort of
problem?
I'm reposting this because if this won't work I'm not going to use this pump.
Your input will be greatly appreciated.

Hi,

I do think that it will works. By reducing inlet and outlet you will create cavitation and higher pressure in the case and the gpm will remain the same.

The only way to reduce gpm in a pump is to lower rpm. A pump have gears inside. So the rpm controls directly the gpm.

You may install flow divider or flow control but again it is not the best solution. Install the right pump for you.
 
   / Can you reduce gpm this way? #5  
You definitely do not want to restrict the inlet of a gear pump. And unless the pump has an internal pressure relief valve you do not want to restrict the outlet either.

Tell us more about what you are trying to do and we can then offer suggestions appropriate to your application.
 
   / Can you reduce gpm this way? #6  
JJ has the answer!
Suggest the variable version as that way you will be sure to get the result you want.
I have seen those used an vibrators to shake loose wet gravel in a slinger truck operation.
Varying the vibrator speed caused proper harmonics to handle all kinds of wet gravel applications.
 
   / Can you reduce gpm this way?
  • Thread Starter
#7  
Going to use the pump to operate a Dual 340 front end loader using a Cross 30 gpm open center control valve with an adjustable 2500 relief valve.
 
   / Can you reduce gpm this way? #9  
I agree with J_J on the compensated flow control. Be sure to take the EF port on that valve back to tank. Do just plug it as that will cause your pump to run at relief whenever the flow is restricted with the valve. You could also use the EF port as a power beyond to power other open center circuits. Install the flow control just prior to the inlet to the control valve and you will be able to regulate the max speed of all your loader functions.
 
   / Can you reduce gpm this way? #10  
TACO - HVAC

It could also be worked on a pressure basis where the outlet pressure is controlled.

If the pump has excessive flow rate it may be easiest to work with the pressure control rather than flow control.:D
 

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