55 psi: that’s the pressure switch cut‑off. When system pressure reaches ~55 psi, the switch turns the pump off.
3 GPM: that’s the open‑flow (low back‑pressure) rate. It’s the max flow with minimal restriction.
As back‑pressure rises (smaller nozzles, longer/higher piping), flow drops along the pump’s performance curve. Near 55 psi the flow will be close to zero, and the switch will shut the pump off.
By vevor