Appeal No. 2006-1809 Page 4
Application No. 09/975,386
18, and more preferably, after the adhesive 24 has been cured. By
forming the perforations 26 after the facing layer 20 is adhered to
the insulation layer 18 and after the adhesive 24 is cured, the
perforations 26 are substantially void or free of the adhesive 24.
Conversely, if the perforations 26 were formed in the facing layer
20 prior to curing the adhesive 24, the adhesive 24 could
completely or at least partially fill the perforations 26. The
importance of the perforations 26 being substantially void of the
adhesive 24 is twofold. First, forced gas units benefiting from this
invention may be subject to various flame spread and smoke test
standards. In particular, HVAC units are required to pass United
Laboratories flame spread and smoke development test standard
UL 2550. In order to pass the test standard defined in UL 2550,
the perforations 26 need to be substantially void of the adhesive
24. Second, if the adhesive 24 were present in the perforations 26,
the intended function of the perforations 26, which is to allow
sufficient gas flow through the facing layer 20, would be defeated
or at least compromised. Specifically, the flow rates across the
pressure-balancing regions 20c, 20d cause a relatively large drop
in the static pressure acting on the outer surface 20a within the
pressure-balancing regions 20c, 20d. In turn, the drop in the static
pressure acting on the outer surface 20a creates a relatively high
difference in the static pressures acting on the outer and inner
surfaces 20a, 20b within the pressure-balancing regions 20c, 20d.
The perforations 26 allow for the venting of the relatively high
static pressure acting on the inner surface 20b to balance or at least
adequately reduce the pressure differential between the static
pressures acting on the outer and inner surfaces 20a, 20b. If the
flow of air through the perforations 26 is restricted by the presence
of the adhesive 24 within the perforations 26, the relatively high
static pressure differential between the outer and inner surfaces
20a, 20b could cause the pressure-balancing regions 20c, 20d to
balloon or be drawn away from the side panels 14a, 14b. In turn,
this ballooning effect could cause the facing layer 20 and the
insulation layer 18 to become separated. By allowing air to flow
through the facing layer 20, the perforations 26 reduce the static
pressure differential between the outer and inner surfaces 20a, 20b.
As such, the facing layer 20 is less likely to balloon. In turn, the
facing layer 20 and the insulation layer 18 are less likely to
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Last modified: November 3, 2007