In a compensated flow control valve, the pressure differential across the orifice is not affected by a change in the load. The constant pressure differential across the orifice will produce a constant flow through the orifice.
A by-pass type pressure compensated flow control valve automatically adjusts the flow to load changes.
The amount of flow through the valve depends on the size of the orifice. Any change in oil flow through the orifice creates a change in pressure on the upstream side of the orifice. The same pressure change acts against the dump valve and spring, causing excess oil to flow back to the tank.
NOTE: The “combined orifice with dump valve” is also a compensated flow control valve