standard:GB,BS,DIN,AWWA,ISO PN0.6-2.5MPa DN80-600mm material: grey cast iron, ductile cast iron It is used to clean the foreign matters in the medium to protect the valve and equipment operate normally.standard:GB,BS,DIN,AWWA,ISOPN0.6-2.5MPaDN80-600mmmaterial: grey cast iron, ductile cast iron backwash filter