The correct selection of a regulator is not based solely on the connection diameter. Actual pressures and the required flow rate must be taken into account.

Inlet pressure

The regulator must operate correctly across the entire possible range of upstream pressure.

Outlet pressure

The spring or pilot range must cover the desired downstream setpoint.

Maximum flow rate

The regulator must be able to supply the peak demand without excessive pressure drop.

Minimum flow rate

Stability at low loads is also important. An oversized regulator may struggle to control small flow rates.

Final selection

Sizing data and manufacturer curves are used, not just a rule of thumb.