KESSEL backwater valve KE73050 Staufix DN 50 made of plastic KESSEL double backwater valve Staufix for faecal-free waste water, made of plastic. Two Klappen self-closing, one of them as a manually lockable emergency lock. Inlet/outlet to the connection for HT pipe according to DIN 19560. Standard: DIN EN 13564 type 2 Installation body: gray Nominal size: DN 50 (DA 50 mm) Installation type: exposed waste water line