knuckle joints may be of aluminum or other non-ferrous metal. Valves shall
close with maximum leakage of 0.15 or 0.26 meter per second 30 or 52 fpm
average velocity over the valve face area at 250 or 750 Pa one or 3 inch
water column corresponding static pressure on high pressure side of the
valve.
2.3
DUCTS OF PRESSURE CLASSES 750 Pa 3 INCH WATER GAGE OR LESS
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NOTE: Do not use insulation liners for ductwork at
infectious areas in hospitals, such as operational
suites, nurseries, pathological facilities,
intensive care units, and surgical wards; use
factory prefabricated sound attenuators instead.
For brig facilities, fibrous glass ductwork should
not be used in inmate housing area, areas accessible
to inmates, nor areas with concrete, gypsum board,
or plaster ceilings. Do not use fibrous glass ducts
within 300 mm 12 inches of electric or fuel fired
heaters.
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Except as specified or indicated otherwise, construction, metal gage,
hangers and supports, and reinforcements shall conform with SMACNA HVAC
Duct Const Stds, except that ducts with pressure classifications below 500
Pa 2 inch water gage that are located outside of the conditioned space
shall have a seal class C. Ductwork shall be airtight and shall not
vibrate or pulsate when system is in operation. Pressure sensitive tape
shall not be used as a primary sealant on ductwork with pressure
classifications above 250 Pa one inch water gage. Air leakage shall be
less than 5 percent of the system capacity. Construct ductwork of
[galvanized steel] [or] [aluminum].
2.3.1
Curved Elbows
Make a centerline radius not less than 1 1/2 times the width or diameter of
the duct.
2.3.2
Laps
Make laps at joints in the direction of air flow. Space button-punch or
bolt-connection in standing seams at fixed centers not greater than 150 mm
6 inches. Longitudinal locks or seams, known as "button-punch snap-lock,"
may be used in lieu of Pittsburg Lock [, but will not be permitted on
aluminum ducts].
2.3.3
Fittings
Provide elbows, vaned elbows, take-offs, branch connections, transitions,
splitters, volume dampers, fire dampers, flexible connections, and access
doors. Provide factory fabricated airtight, and noncorrosive test holes
with screw cap and gasket.
2.3.4
Acoustical Attenuator Systems
2.3.4.1
Acoustical Duct Lining
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NOTE: When internal lining is shown, the designer
SECTION 15810N
Page 14
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