Damper Assembly

2.4

DAMPERS

Provide dampers in air ducts.

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NOTE: Use parallel blade dampers for mixing boxes

and where two-position control is required. Use

opposed blade dampers for modulating applications

for face and bypass control.

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2.4.1

Damper Assembly

Damper shall conform to SMACNA HVAC Duct Const Stds. A single damper

section shall have blades no longer than 1219 mm 48 inches and shall be no

higher than 1829 mm 72 inches. Maximum damper blade width shall be 200 mm

8 inches. Larger sizes shall consist of a combination of sections.

Dampers shall be steel or other materials where indicated. Flat blades

shall be made rigid by folding the edges. Provide blades with compressible

seals at points of contact. Provide channel frames of dampers with jamb

seals to minimize air leakage. Dampers shall not leak in excess of 51 L/s

per square meter 10 cfm per square foot at 996 Pa 4 inches water gage

static pressure when closed. Seals shall be suitable for an operating

temperature range of minus 40 degrees C to 93 degrees C 40 degrees F to 200

degrees F. Dampers shall be rated at not less than 10 m/s 2000 fpm air

velocity. Moving parts of the operating linkage in contact with each other

shall consist of dissimilar materials. Damper axles shall be 13 mm 0.5 inch

minimum plated steel rods supported in the damper frame by stainless steel

or bronze bearings. Blades mounted vertically shall be supported by a

non-ferrous dissimilar thrust bearings.

Pressure drop through dampers

shall not exceed 12 Pa 0.05 inch water gage at 5 m/s 1,000 fpm in the

wide-open position. Frames shall not be less than 51 mm 2 inches wide.

Dampers shall be tested in accordance with AMCA 500-D.

2.4.2

Operating Links

Operating links external to dampers, such as crankarms, connecting rods,

and line shafting for transmitting motion from damper actuators to dampers,

shall withstand a load equal to at least twice the maximum required

damper-operating force. Rod lengths shall be adjustable. Links shall be

brass, bronze, zinc-coated steel, or stainless steel. Mating parts shall

consist of dissimilar materials. Working parts of joints and clevises

shall be brass, bronze, or stainless steel. Adjustments of crankarms shall

control the open and closed position of dampers.

2.5

FIRE PROTECTION DEVICES

Provide smoke detectors in return and supply air ducts on the downstream

side of the filters in accordance with NFPA 90A, except as otherwise

indicated. Provide UL listed or FM approved detectors for duct

installation.

2.5.1

Smoke Detectors

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NOTE: Choose one of the following options.

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SECTION 15901N

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