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Patented
Design -
Method C has features
protected by U.S. Patent #5,301,479 with the following advantages,
as compared to conventional installation methods A and B.
Mounting
Locations
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Methods A and B are mounted on the outside wall of the building
over the framed opening. The top of the hood becomes the shipping
height of the building, and the floor-to-ceiling height of the
building needs to be raised to allow for the bottom of 15"
long explosion proof light fixture to be clear of the top of the
door, out of the way of entering forklift load or mast. Method
C is mounted securely midway within a 1/4" thick tubular
frame opening. The height of the roof is the shipping height.
Internally, the light fixtures, suppression system nozzles, etc.
are safe out of the way.
Forklift
Damage Protection -
Overhead roll-up doors are specified because they receive less
damage from forklifts than swing-type doors. However, as in Methods
A and B, overhead roll-up door vendors manufacture the hoods at
the top of the door out of very thin steel. This means the leading
edge of the bottom corner of the hood is frequently damaged by
the load or the top portion of the forklift mast. Method C's leading
bottom edge is reinforced with steel angle upon which a 10 gauge
faceplate is attached, providing protection against forklift damage.
NOTE: 10 gauge steel has, by weight (more is stronger), 281% more
steel than 18 gauge, and 642% more steel than 25 gauge!
Fusible
Link Operation Reliability -
Methods
A and B have difficulty in penetrating the roof or wall of the
building for the cable release to be attached to a ceiling-mounted
fusible link. Considering ice, snow, dirt, debris and vandalisim,
the actual release during fire is questionable. Method C has the
ideal cable release and attachment for the fusible link protected
inside.
Component
and Hood Security -
Methods
A and B, being outside in the weather, could have the operation
of the components affected over time by ice, snow, dirt and debris
jamming operation. In addition, the hood and components are exposed
to damage by vandals and intruder unauthorized operation. Method
C has all operating components and hood tucked inside the building,
safe from negative effects from outside influences.
Moisture
Control -
Method
A has the bottom of the door curtain stopping at a steel angle
that is flush with the threshold opening of the building. This
will allow wind-driven rain that may penetrate the joints of the
door curtain's steel slats and/or condensation of moisture to
accumulate on the inside surface of the uninsulated steel curtain
(fire rated overhead roll-up doors are not the U.L. or FM approved
with insulated slats), causing water to drain down into the sump
floor of the building. This will cause a false chemical spill
alarm. Methods B and C have the angle moved a few inches down
from the building threshold so the water cannot get into the sump
and drain out a weep hole in the angle. (This is part of Haz-Safe
Buildings' Patent #5,301,479.)
Blast
Relief Capability -
Large
overhead roll-up doors do not have the strength to match the wall's
blast strength and could be used as blast relief in place of relief
panels. Blast protection is best if implemented by a dual fan
posi-ventilation system which eliminated heavier-than-air chemical
fumes so that an electrical or static spark has nothing to ignite,
therefore eliminating need for blast relief.
Appearance
-
The
hood, components and chain operator exposed outside the building,
as well as jutting out over the roof line, are not aesthetically
pleasing in Methods A and B. However, integrating the entire door
into the building wall provides a more architecturally smooth
surface on the exterior because the awkward looking hood is completely
hidden. |