Duckbill Check Valve 1,ISO9001 and ISO14001 2,DN50~3000mm 3,Material:rubber,steel 4,12 years OEM manufacturer experience Duckbill Check Valve,adjustable check valve,duckbill valve1:Compared with traditional flat valves,it owns obvious advantages: 1, It will start and close automatically according to the differential water pressure,safe,reliable,noiseless,no manual operation or maintenance 2, ...