quote:

I understand how the pump works, what I don't understand is this:

"...Place a Pressure Compensated Flow Control at the inlet to the 1 GPM Flow Directional Control valve and none at the 15 GPM valve.

Sense each flow line so the pump never goes to pressure until a load on one of the actuators is required..."

I understand pressure compensating units sense the load of a closed center system, what I don't understand is how to sense the load in an open center system without changing the 2 open center valves that currently direct the current 1gpm.

Typically a Load Sense circuit has 3 Position DCV's that have "P" Blocked and "A" and "B" to "T" Center condition. A pilot line from each "A" and "B" Port goes to Check Valves plumbed so any of the Load Sense signals are sent to the Load Sense port on the Pump.

That means there is no pressure feedback to the pump when the DCV's are centred and the pump will be at no flow and 150-200 PSI.

When a valve is shifted and pump flow is directed to an actuator the sensing line from that valves working port sends the pressure required by the actuator to the pumps Load Sensing port and causes the pump to increase pressure to the load plus te 150-200 PSI preset pressure. The circuit continues to operate at the pressure required by the load plus the bias pressure so pressure drop is only 150-200 PSI while the actuator is running.

If another valve is used simultaneously, the Load Sense port at the pump will see the highest load pressure due to the Check Valves and set the pump at 150-200 PSI above that. You can see a Two Actuator circuit in the Basic Ebook from a link on the Home Page of this Forum. Look in Chapter 8 Page 15 for a schematic and an explanation of the operation.

Also, you skipped the question regarding if I was missing something or if the system you proposed would only operate one circuit (1gpm or 15gpm) at a time. The way I understand it, the pump would differ to the lessor pressure (unless there is some divider you're thinking of) and would run the other circuit at that pressure (plus the extra 150-300psi) as well.