serpentine design springs suspended under tension; cross bracing, if
required, shall be welded to frame so as not to interfere with spring
action. Cushions shall be polyurethane foam cemented to burlap sheeting;
shall have a minimum thickness of 44 mm 1-3/4 inches throughout for
coil-spring type construction, and 75 mm 3 inches at front edge, 44 mm
1-3/4 inches at rear edge, and 25 mm 1 inch throughout the other portions
for nonsag spring units. Panel side covers shall be made without welts.
Top and front cover shall have size boxing of fabric upholstery material.
2.2.2.2
Plywood Seat Units
Upholstered plywood seat unit shall be minimum 19 mm 3/4 inch thick, 7-ply,
electronically-glued hardwood plywood with minimum of four 1/4-20 threaded
inserts for attachment of seat hinges. Cushion material shall be
high-density fire-retardant polyurethane foam, minimum 89 mm 3-1/2 inches
thick, cored for comfort. Outside of seat bottom shall be fully
encapsulated in 6 mm 1/4 inch slab polyurethane foam. Padding materials
shall be fully glued to plywood panels with contact cement.
2.2.3
Hinges
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NOTE: Push-back mechanisms provide more aisle space
when the seats are not occupied. Normally, this
type of accessory is used only when appearance and
convenience is of prime importance, and would not be
used in auditoriums.
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Hinges shall be a counterweight mechanism using gravity to return to the
upright position or of the full compensating type, completely enclosed,
totally independent, free and easy in operation, and capable of
compensating for circular installation, variation in installation
conditions, and unevenness of floors. [Hinge mechanism shall be of the
push-back type to allow additional aisle space while in an open position.]
Each hinge shall have a noiseless, self-rising seat device, shall rise
automatically to a uniform safety position of 3/4 fold at all times, and
shall fold 100 percent when additional pressure is applied, to provide
additional clearance. The hinges shall have oil-impregnated,
self-lubricating, metal or brass alloy bearings that will not require
further lubrication, or nylon bushings. Hinges shall have a spring tension
adjustment mechanism to allow manual compensation for normal wear and
fatigue.
2.2.4
Standards
2.2.4.1
Floor Standards
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NOTE: Few manufacturers use cast iron standards
compared to those using steel risers; standards
should not be specified without options.
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Floor standards shall be tublar steel, sheet steel, or cast iron. The
standards shall be formed to fit the floor incline so that the standards
will be vertical and the hinge point will be at a height that will maintain
proper relation of seat to floor. The feet shall be formed to eliminate
tripping hazards and shall have holes for bolt attachment to the floor.
SECTION 12610
Page 8
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