Page 88 - 2018_IMC

DUCT SYSTEMS

tion area that share a common air recirculation accordance with Section 2603.9 of the International
path with the fabrication area. Building Code.
602.2.1.1 Wiring. Combustible electrical wires and Exceptions:
cables and optical fiber cables exposed within a plenum 1. Foam plastic in plenums used as interior wall
shall be listed and labeled as having a peak optical den- or ceiling finish or interior trim shall exhibit a
sity not greater than 0.50, an average optical density not flame spread index of 75 or less and a smoke-
greater than 0.15, and a flame spread distance not developed index of 450 or less when tested in
greater than 5 feet (1524 mm) when tested in accor- accordance with ASTM E84 or UL 723 at the
dance with NFPA 262, or shall be installed in metal maximum thickness and density intended for
raceways or metal sheathed cable. Combustible optical use, where it is separated from the airflow in
fiber and communication raceways exposed within a the plenum by a thermal barrier complying
plenum shall be listed and labeled as having a peak with Section 2603.4 of the International
optical density not greater than 0.5, an average optical Building Code.
density not greater than 0.15, and a flame spread dis-
tance not greater than 5 feet (1524 mm) when tested in 2. Foam plastic in plenums used as interior wall
accordance with UL 2024. Only plenum-rated wires or ceiling finish or interior trim, shall exhibit a
and cables shall be installed in plenum-rated raceways. flame spread index of 75 or less and a smoke-
developed index of 450 or less when tested in
602.2.1.2 Fire sprinkler piping. Plastic fire sprinkler accordance with ASTM E84 or UL 723 at the
piping exposed within a plenum shall be used only in maximum thickness and density intended for
wet pipe systems and shall be listed and labeled as hav- use, where it is separated from the airflow in
ing a peak optical density not greater than 0.50, an the plenum by corrosion-resistant steel having
average optical density not greater than 0.15, and a a base metal thickness of not less than 0.0160
flame spread distance not greater than 5 feet (1524 mm) inch (0.4 mm).
when tested in accordance with UL 1887.
3. Foam plastic in plenums used as interior wall
602.2.1.3 Pneumatic tubing. Combustible pneumatic or ceiling finish or interior trim, shall exhibit a
tubing exposed within a plenum shall be listed and flame spread index of 75 or less and a smoke-
labeled as having a peak optical density not greater than developed index of 450 or less when tested in
0.50, an average optical density not greater than 0.15, accordance with ASTM E84 or UL 723 at the
and a flame spread distance not greater than 5 feet maximum thickness and density intended for
(1524 mm) when tested in accordance with UL 1820. use, where it is separated from the airflow in
the plenum by not less than a 1-inch (25 mm)
602.2.1.4 Electrical equipment in plenums. Electrical
equipment exposed within a plenum shall comply with thickness of masonry or concrete.
Sections 602.2.1.4.1 and 602.2.1.4.2. 602.2.1.7 Plastic plumbing piping and tubing. Plastic
602.2.1.4.1 Equipment in metallic enclosures. piping and tubing used in plumbing systems shall be
Electrical equipment with metallic enclosures listed and labeled as having a flame spread index not
greater than 25 and a smoke-developed index not
exposed within a plenum shall be permitted.
greater than 50 when tested in accordance with ASTM
602.2.1.4.2 Equipment in combustible enclosures. E84 or UL 723.
Electrical equipment with combustible enclosures
exposed within a plenum shall be listed and labeled Exception: Plastic water distribution piping and
for such use in accordance with UL 2043. tubing listed and labeled in accordance with UL
2846 as having a peak optical density not greater
602.2.1.5 Discrete plumbing and mechanical prod- than 0.50, an average optical density not greater than
ucts in plenums. Where discrete plumbing and 0.15, and a flame spread distance not greater than 5
mechanical products and appurtenances are located in a feet (1524 mm), and installed in accordance with its
plenum and have exposed combustible material, they listing.
shall be listed and labeled for such use in accordance 602.2.1.8 Pipe and duct insulation within plenums.
with UL 2043.
Pipe and duct insulation contained within plenums,
602.2.1.6 Foam plastic in plenums as interior finish including insulation adhesives, shall have a flame
or interior trim. Foam plastic in plenums used as inte- spread index of not more than 25 and a smoke devel-
rior wall or ceiling finish or interior trim shall exhibit a oped index of not more than 50 when tested in accor-
flame spread index of 25 or less and a smoke-devel- dance with ASTM E84 or UL 723, using the specimen
oped index of 50 or less when tested in accordance with preparation and mounting procedures of ASTM E2231.
ASTM E84 or UL 723 at the maximum thickness and Pipe and duct insulation shall not flame, glow, smolder
density intended for use, and shall be tested in accor- or smoke when tested in accordance with ASTM C411
dance with NFPA 286 and meet the acceptance criteria at the temperature to which they are exposed in service.
of Section 803.1.2 of the International Building Code. The test temperature shall not fall below 250ºF
As an alternative to testing to NFPA 286, the foam (121ºC). Pipe and duct insulation shall be listed and
plastic shall be approved based on tests conducted in labeled.

2018 INTERNATIONAL MECHANICAL CODE  71
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