Flanged Duckbill Check Valve

A Flanged Duckbill Check Valve is about as simple as a check valve gets: a rubber sleeve on a flange, nothing that swings or slides. The Flanged Duck Bill Check Valve spelling shows up in older catalogues and both mean the same part. Duckbill Flanged Style Check Valves are used wherever reverse flow would flood a line, from DN50 roof drains to DN1200 outfalls. Rubber Duckbill Check Valves cost less than a swing check of the same bore, weigh a fraction of it, and never seize after a dry spell. The sleeve is EPDM, neoprene, NBR or natural rubber, usually two plies of nylon or polyester, moulded in one shot so the flange face and the lips come out as one part. There is no seat, no disc and no hinge pin, therefore no wear point. A cast iron or ductile iron body takes the bolt load, with epoxy inside and out at 250 microns. Pressure class is PN10 or PN16, temperature -10 C to 80 C, cracking pressure around 0.5 kPa. Flange drilling can be DIN, ANSI 150, JIS 5K or BS, and the paint colour is…