Thread: How does a pressure control valve work exactly? If we start closing the control valve, does pressure increase?

or decrease? and to be clear, since we are closing the control valve and therefore restricting flow, wouldnt the liquid pressure up before the control valve?

A pressure control valve is a pressure regulator. Its basic requirement is the input pressure must be higher than the output.
It automatically adjusts flow to maintain a steady output pressure.
It is not something you shut or open, but just adjust output pressure (if meant to be variable).
Most are set for a particular out pressure, and sealed off at that.