flange duckbill valve 1,ISO9001 and ISO14001 2,DN25mm~5000mm 3,Material:rubber,steel 4,12 years OEM manufacturer experience flange Check Valve,rubber check valves,duckbill check valve1:Basic introduction: The rubber Duck-bill check valve is all rubber reinforced. It consists in an elastomer sleeve flattened in one end. The Duckbill valve can only be opened when the forward flow lifts the sealing ...