Annulus (firestop)

The annulus, or annular space, is the space between a penetrant and anything that surrounds it, such as the sides of an opening or a sleeve, as the case may be. It is named after the corresponding geometric concept due to its shape.

Sprinkler branch pipe through-penetration with plastic sleeve - missing firestop in concrete fire separation. The space between the sleeve and the pipe is the annulus or annular space

External links

External examples of the use of the term.

• Annulus, a term used within a firestop patent
• Annulus, as used in UL System C-AJ-1557 Firestop System, Configuration A