本文件规定了金属止回阀的一般要求，金属止回阀锻造、铸造或制造为直形、角形或斜形（见EN 736-2），端部连接为法兰连接或对夹连接、对焊、承插焊或螺纹连接。本文件适用于所有工业应用的金属止回阀。相关应用标准中给出的附加要求可能适用于用于更具体应用的止回阀（例如，用于水工业、化学和石化过程工业、天然气分配工业）。卫生止回阀和回流防止污染止回阀不在本文件范围内。注1:双阀瓣型和倾斜阀瓣型也基于蝶阀，在本文件范围内。所涵盖的标称尺寸范围为:-DN 8，DN 10；DN 12，DN 15；DN 20；DN 25；DN 32；DN 40；DN 50；DN 65；DN 80；DN 100；DN 125；DN 150；DN 200；DN 250；DN300；DN 350；DN 400；DN 450；DN 500；DN 600；DN 700；DN 750；DN 800；DN 900；DN 1 000；DN 1 200。DN 8和DN 12不用于PN指定的法兰端连接。DN 8、DN 10和DN 12不用于等级指定的法兰端连接。DN 750仅用于指定等级的止回阀。承插焊接端止回阀和螺纹端止回阀的范围限制在DN 8至DN 65之间。毛细管和压缩端阀门的标称直径范围为6 mm至110 mm。所涵盖的压力名称范围为:a） 对于法兰端和对夹式端铸铁阀体:-PN 2,5；PN 6；PN 10；PN 16；PN 25；-125级；250级；b） 对于钢制法兰端、对夹式和对焊端体:-PN 2,5；PN 6；PN 10；PN 16；PN 25；PN 40；PN 63；PN 100；PN 160；PN 250；PN 320；PN 400；-150级；300级；600级；900级；1500级；2500级；c） 对于钢制承插焊端和螺纹端体:-PN 40；PN 63；PN 100；-600级；800级。注2:800级是承插焊和螺纹端止回阀广泛使用的等级名称。d） 对于铜合金材料的法兰端和对夹式阀体:-PN 2,5；PN 6；PN 10；PN 16；PN 25；PN 40；-150级；300级；e） 对于铜合金材料的螺纹端、毛细管端和压缩端体:-PN 16；PN 20；PN 25；PN 32；PN 40；-125级；250级。DN与NPS之间的对应关系见附录B。

This document specifies the general requirements for metallic check valves, which are forged, cast or fabricated in straight, angle or oblique pattern (see EN 736‐2) with end connections flanged or wafer, butt welding, socket welding, or threaded. This document applies to metallic check valves used for all industrial applications. Additional requirements given in the relevant application standards may apply to check valves used for more specific applications (e.g. for the water industry, the chemical and petrochemical process industry, the gas distribution industry). Sanitary check valves and back flow prevention anti-pollution check valves are excluded from the scope of this document. NOTE 1 Double disc type and tilting disc type are also based on butterfly valve and are in the scope of this document. The range of nominal sizes covered is: - DN 8, DN 10; DN 12, DN 15; DN 20; DN 25; DN 32; DN 40; DN 50; DN 65; DN 80; DN 100; DN 125; DN 150; DN 200; DN 250; DN 300; DN 350; DN 400; DN 450; DN 500; DN 600; DN 700; DN 750; DN 800; DN 900; DN 1 000; DN 1 200. DN 8 and DN 12 are not used for PN designated flanged end connections. DN 8, DN 10 and DN 12 are not used for Class designated flanged end connections. DN 750 is used for Class designated check valves only. Socket welding end check valves and threaded end check valves are limited to the range DN 8 to DN 65. The range of nominal diameters for capillary and compression end valves is 6 mm to 110 mm. The range of pressure designations covered is: a) for flanged end and wafer type end cast iron bodies: - PN 2,5; PN 6; PN 10; PN 16; PN 25; - Class 125; Class 250; b) for flanged end, wafer type and butt welding end bodies in steel materials: - PN 2,5; PN 6; PN 10; PN 16; PN 25; PN 40; PN 63; PN 100; PN 160; PN 250; PN 320; PN 400; - Class 150; Class 300; Class 600; Class 900; Class 1 500; Class 2 500; c) for socket welding end and threaded end bodies in steel materials: - PN 40; PN 63; PN 100; - Class 600; Class 800. NOTE 2 Class 800 is a widely used Class designation for socket welding and threaded end check valves. d) for flanged end and wafer type bodies in copper alloy materials: - PN 2,5; PN 6; PN 10; PN 16; PN 25; PN 40; - Class 150; Class 300; e) for threaded end, capillary end and compression end bodies in copper alloy materials: - PN 16; PN 20; PN 25; PN 32; PN 40; - Class 125; Class 250. The correspondence between DN and NPS is given for information in Annex B.