The Conbraco Industries 10-407-05 3/4" M x 3/4" F 30# 535,000 BTU Relief Valve is a high-performance safety valve designed to protect HVAC and hydronic systems from excess pressure. It operates by automatically releasing pressure when system levels exceed the 30-psi rating, ensuring safe and reliable operation. https://www.partshnc.com/10-407-05-conbraco-industries-34-mx34-f-30-535000bturelf