The ES-Series ratio regulators are used in applications where gas to air proportional flow is required. The gas flow is controlled as a function of the air pressure through a loading line which connects into the top of the regulator.

As the system air pressure increases, it forces the ratio regulator valve to open causing the outlet pressure to increase until the two pressures balance. As the load line pressure increases, the ratio of the outlet pressure to the load line pressure will be slightly less than 1:1.

The ratio regulators have a bias adjustment for varying the gas flow when setting the burner at low fire. It can be used to increase or decrease the gas flow resulting in gas rich or lean combustion. The adjustment is restricted in the gas rich direction, therefore, limiting the gas flow at zero air pressure.