Available for settings between 0.5 to 2.25 psig / 34 to 155 mbar, the 289 Series relief valve is a throttling relief valve used downstream of pressure regulators to protect the downstream system from overpressure. A smooth throttling action minimizes pressure surges in the system during emergency operation. This unit features a pitot tube booster to achieve the highest possible relief capacity with a minimum build-up of the system pressure. 289H relief valve is installed between large second-stage regulators (such as the S202G or S302G Series) and the burner to provide high capacity relief. They are ideal for low-pressure settings due to the increased sensitivity provided by the large diaphragm area.