If this sounds familiar, it may be because I wrote about it back in 2013. At that time, there wasn’t a clear answer to the question…
Can a delayed-action closer be installed on a fire door?
A delayed-action closer is self-closing, but holds the door open for a minute or two when the door is opened fully. This is a function of the valves that control the flow of fluid; it is not an electronic feature. Installing a delayed-action closer on a fire door with the possibility that the door could stand open for a minute (+/-) before beginning to close, is not one of the things that keeps me up at night. But because it was not specifically addressed in the model codes, interpretations were inconsistent.
A clarification was added to the 2018 International Building Code (IBC), which provides a solid answer to the question:
7126.96.36.199 Delayed-action closers. Doors required to be self-closing and not required to be automatic closing shall be permitted to be equipped with delayed-action closers.
This paragraph is found in Section 716 – Opening Protectives, which means that delayed-action closers CAN be used on fire door assemblies. Note that this added section does not include a specific limit on the amount of time that the closing cycle can be delayed.