MSS SP-125-2018涵盖了在线、内部弹簧加载、中心导向止回阀 由灰铸铁或球墨铸铁制成。这些阀门的特点是仅将流体流动限制在一个方向， 用于清洁液体（即不含固体的液体），包括饮用水， 水平和垂直安装的自来水厂和其他工业应用。

MSS SP-125-2018 covers in-line, internally spring-loaded, center-guided check valves made of gray iron or ductile iron. These valves, having the feature of limiting fluid flow to one direction only, are intended for use with clean fluids (i.e., fluids that do not contain solids), including potable water, waterworks, and other industrial applications, in horizontal and vertical installations.