指定法兰管道系统中使用的一系列疏水阀的尺寸，并给出定义。法兰式蒸汽疏水阀的六个基本系列尺寸（以毫米为单位）在表中给出，其标称尺寸范围为DN 15至DN 50，压力范围为PN 40。

Specifies dimensions for a range of steam traps used in flanged pipe systems, and gives definitions. The six basic series of dimensions for flanged steam traps, expressed in millimetres, are given in a table for the nominal sizes ranging from DN 15 to DN 50 inclusive, and for pressures to PN 40 inclusive.