UL 33

1 Scope

1.1 These requirements cover heat responsive links used for fire-protection service. These links consist of devices intended for installation under load conditions such as for use with automatic fire suppression systems; or automatic closure devices for doors, windows, dampers or smoke relief vents.

1.2 Heat responsive links are categorized by temperature rating, type of coating or plating, minimum and maximum design load, and other factors which may have a bearing on their intended use.