ISO 18421:2016规定了救生圈外壳的结构和尺寸。
外壳用于包裹一个救生圈,以保护其免受恶劣天气和人为破坏。
ISO 18421:2016 specifies the construction and dimensions of housing for lifebuoys.
The housing serves to encase a lifebuoy to protect it against deterioration from the elements and against vandalism.