Annulus (firestop)

The Annulus is the space between a penetrant and whatever surrounds it, such as the sides of an opening or a sleeve, as the case may be.Sometimes an annulus can be "offset", meaning that the penetrant is not centred. This is an important bounding consideration in firestopping. If the firestop was tested only to a perfectly centred opening, an offset may disqualify it for use in the field.In legal terms, it is simply a function of the bounding because one is obliged to follow the letter of the certification listing that covers the installed configuration.
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