ISO 4081:2016规定了对于空载质量（如ISO 1176所定义）小于等于3.5 t的车辆，在内燃机中含有1,2-乙二醇基冷却剂的加压或非加压冷却回路中使用的直形或预制橡胶软管和管的要求。此外，本规范还可作为一个分类系统使用，以使原始设备制造商（OEM）能够详细说明特定应用的“线路调用”测试，这些测试不包括在规定的主要类型中（见附录D中的示例）。在这种情况下，软管或管道不会带有任何显示该ISO规范编号的标记，但可能会详细说明OEM自己的识别标记，如其零件图所示。

ISO 4081:2016 specifies the requirements for straight or pre-formed rubber hoses and tubing for use in pressurized or unpressurized cooling circuits containing 1,2-ethanediol-based coolants in internal-combustion engines for vehicles with an unladen mass (as defined in ISO 1176) of 3,5 t or less. In addition, this specification may also be applied as a classification system to enable original equipment manufacturers (OEMs) to detail a "line call-out" of tests for specific applications where these are not covered by the main types specified (see example in Annex D). In this case, the hose or tubing would not carry any marking showing this ISO specification number but may detail the OEM's own identification markings as shown on their part drawings.