Relief Valve

Fisher™ 289 Series Relief Valves or Backpressure Regulators

Fisher 289 Series relief valves are spring-loaded throttling relief valves used as downstream pressure regulators to protect the system from overpressure. A smooth throttling action minimizes pressure surges in the system during relief operation. 289 Series relief valves are ideal for low-pressure settings due to the increased sensitivity provided by a large diaphragm area. 289 Series relief valves are designed for pressure control; they are not ASME safety relief valves.

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

Approximate Weights

Type 289A and 289U: 0.75 Pounds / 0.3 kg 
Type 289H: 1 NPT - 4 Pounds / 2 kg, 2 NPT - 15 Pounds / 7 kg
Type 289HH: 4 Pounds / 2 kg
Type 289L: 15 Pounds / 7 kg

289H: Relief Adjustment Ranges

0.5 to 2.25 psig / 34 to 155 mbar

289H: Maximum Relief (Inlet) Pressure

25 psig / 1.7 bar