With a design off the 106-PG or 06-PG main valve, the 106-RPS-D and 206-RPS-D Pressure Differential Sustaining Valves function by keeping differential pressure at a minimum while allowing easy adjustments.
These valves make use of the 81-RPD pilot valve, which ensures that it is closed tightly against drips when the pressure differential falls below the level of the pilot setting.
The two sensing connections of the 106-RPS-D and the 206-RPS-D makes it so that the valve will only open once the pressures on both the main valve and the 81-RPD pilot valve becomes more than the pilot setting.