While all perimeter joint protection is tested at its maximum joint
width, the maximum joint width of a static perimeter joint protection
is the same as its nominal joint width. This is another difference
between dynamic perimeter joint protection Listings and those
designated as “static”. The dynamic perimeter joint protection is
tested at its maximum joint width, which is larger than the nominal
joint width at which the perimeter joint protection is installed.
Many of the perimeter joint protection systems consist of compressed
insulation, which increases its nominal density when installing into
a perimeter joint that is narrower than the nominal thickness of the
insulation. In all dynamic perimeter joint protection, the effective
compression and the effective density of the insulation decrease
at maximum joint width, which increases heat transfer through it
creating a worse-case ASTM E2307 fire test scenario. It is important
that an understanding of the basic movement principles that affect
the performance of the perimeter joint protection is comprehended.
The depth of the insulation used in all the following examples is the
same.
No movement data is presented in static perimeter joint protection
Listings. The nominal joint width and maximum joint width are the
same for static perimeter joint protection, which is unrealistic for
perimeter joint applications. An unchanged (static) joint width means
that heat transfer through the insulation remains the same for their
nominal joint width and maximum joint width conditions. This is the
best-case fire test scenario. Static perimeter joint protection will
perform better than a dynamic perimeter joint protection that uses
the same nominal width and nominal density insulation because the
former does not experience a decrease in its effective compression
or effective density to be ASTM E2307 fire tested.