... , gas, Oil, acid, alkali and so on. NO.NamePieceMaterialRemark1valve body1HT250 QT400 2valve ball1Metal+NBR Metal+EPDM3valve lid1HT250 QT400 ... 4Bolt2Stainless steel 5Rubber ball1NBR EPDM 2.Name:internal thread ball type check valve1).Size:DN25~ ... , gas, Oil, acid, alkali and so on. NO.NameMaterial1valve bodyQT400 HT2502Type O seal ringNBR3valve lidQT400 HT2504Rubber ballNBR EPDM5BoltA2 ...