Sizing a hydraulic control valve - size for pump flow, or total flow?

[jim_wilson]

I'm working thru a setup I want to install on my Kubota B3200 for a hydraulic thumb on the backhoe. The specs list the "pump flow" as 6.7gpm - and the "total flow" as 9.9gpm. The "steering flow" is listed as 3.2gpm. Steering flow + pump flow = total flow.

Do I need to size the GPM of the valve for pump flow - or total flow? Is the steering system typically completely separate from the regular hydraulics?

 

[SSdoxie]

Backhoe will get pump flow only. It is difficult to find valves rated less than 10 GPM so 6.7 or 9.9 won't make any noticeable difference.

 

[jim_wilson]

Thanks. I've been looking at two different Prince valves that I think will work - one is rated 8gpm and the other is rated at 14. The B3200 has the 6.7gpm pump flow - and the 8gpm valve is cheaper than the 14 , so I was hoping the 8 would work.

 

[SSdoxie]

Thanks. I've been looking at two different Prince valves that I think will work - one is rated 8gpm and the other is rated at 14. The B3200 has the 6.7gpm pump flow - and the 8gpm valve is cheaper than the 14 , so I was hoping the 8 would work.

the 8 GPM would be the better choice.

 

[CalG]

It would seem counter to good sense to demand a full flow capacity valve, and then maybe put a flow restriction on it to keep the actuator speed in line .....

If the valve is part of a power beyond system, then flow from inlet to outlet should match system flow to keep restriction and heating to a minimum.