Fisher 289 Series Relief Valve or Backpressure Regulator are spring-loaded throttling relief valve used downstream of pressure regulators to protect the downstream system from overpressure. 289 Series Valves are ideal for low-pressure settings due to the increased sensitivity provided by a large diaphragm area. Designed for pressure control; they are not ASME safety relief valves.
**See Ordering Guide and Specification Sheet in the Attachment Tab below**
Specifications:
Body Sizes and End Connection Styles: Types 289A and 289U: 1/4 NPT || Type 289H: 1, 2 NPT || Type 289HH: 1 NPT || Type 289L: 3/4, 1 NPT || Type 289U: 1/4 NPT
Maximum Allowable Relief (Inlet) Pressure: 100 psig / 6.9 bar
Relief Set Pressure Ranges (5 models): 5wc to 50 psig / 25mbar to 3.5 bar
Pressure Registration: Internal
Temperature Capabilities: Nitrile (NBR) and Neoprene (CR) Elastomers: -20 to 150°F / -29 to 66°C Fluorocarbon (FKM): 20 to 300°F / -7 to 149°C Available with Types 289H and 289HH only
289H: Relief Adjustment Ranges: 0.5 to 2.25 psig / 34 to 155 mbar
289H: Maximum Relief (Inlet) Pressure: 25 psig / 1.7 bar
The Fisher Type 289H Backpressure Regulator is available for settings between 0.5 to 2.25 psig/34 to 155 mbar. The smooth throttling action minimizes pressure surges in the system during emergency operation. The unit features a pilot tube booster to achieve the highest possible relief capacity with a minimum build-up of the system pressure. The 289H is installed between large second-stage regulators and the burner to provide high capacity relief. They are also ideal for low pressure settings due to increased sensitivity provided by the large diaphragm area.
