Fisher 289L Gas Relief Valve: Essential Safety Equipment for Gas Systems

The Fisher 289L Gas Relief Valve serves as a vital safety device within gas systems. Its primary function is to promptly discharge excess gas when the system pressure rises abnormally, effectively preventing various safety accidents caused by excessive pressure and ensuring the smooth and safe operation of the gas system.​
Design and Structure​
Valve Body Material: The valve body is typically made of high – strength cast iron or steel. Cast iron, with its lower cost and good casting properties, can meet the requirements of general working conditions. Steel, on the other hand, offers higher strength and toughness, performing well in harsh environments or under high – pressure working conditions. It can effectively resist the corrosion of gas and pressure impacts, ensuring the structural integrity of the valve body during long – term use.​
Internal Components: It is equipped with high – precision diaphragms and valve discs inside. The diaphragm is extremely sensitive to pressure changes. Once the system pressure rises, the diaphragm deforms due to the applied force. The valve disc is linked to the diaphragm and is driven by the diaphragm to open or close, thereby achieving the discharge and cutoff of gas. These components are manufactured with sophisticated processes, ensuring the sensitivity and reliability of the relief valve.​
Working Principle​
Under normal operating conditions, gas flows stably within the set pressure range. At this time, the Fisher 289L Gas Relief Valve remains closed, with the valve disc closely fitting the valve seat to prevent gas leakage. However, when the pressure in the gas system rises due to various reasons such as equipment failure or sudden changes in flow rate and exceeds the pre – set relief pressure value, the pressure acts on the diaphragm, causing the diaphragm to displace upward. This displacement of the diaphragm drives the valve disc to leave the valve seat, allowing gas to be discharged from the relief port, thereby reducing the system pressure. When the system pressure drops back to the normal range, the diaphragm returns to its original position under the combined action of its own elasticity and the system pressure, and the valve disc closes again, and the relief valve stops working.