Pneumatic flanged butterfly valves consist of a flanged butterfly valve body and a pneumatic actuator. The valve body's flanges connect to pipeline flanges, offering relatively reliable sealing performance. Based on sealing type, these valves can be categorized into elastic seal and metal seal variants. Elastic seal materials include nitrile rubber and fluororubber. Hard-seal butterfly valves feature multi-layer metal hard seals, combining the advantages of elastic seals with excellent sealing performance even under low-temperature conditions.