HomeMy WebLinkAboutCh 15 Exhaust SystemsCHAPTER 15 EXHAUST SYSTEMS
SECTION M1506 EXHAUST DUCTS AND EXHAUST OPENINGS
M1506.1 Duct construction.
Where exhaust duct construction is not specified in this chapter, construction shall comply with Chapter 16.
M1506.2 Duct length.
The length of exhaust and supply ducts used with ventilating equipment shall not exceed the lengths determined in accordance with Table M1506.2.
Exception: Duct length shall not be limited where the duct system complies with the manufacturer’s design criteria or where the flow rate of the
installed ventilating equipment is verified by the installer or approved third party using a flow hood, flow grid or other airflow measuring device.
TABLE M1506.2
DUCT LENGTH
For SI: 1 foot = 304.8 mm.
a.Fan airflow rating shall be in acordance with ANSI/AMCA 210-ANSI/ASHRAE 51.
b.For noncircular ducts, calculate the diameter as four times the cross-sectional area divided by the perimeter.
c.This table assumes that elbows are not used. Fifteen feet of allowable duct length shall be deducted for each elbow installed in the duct run.
d.NL = no limit on duct length of this size.
e.X = not allowed. Any length of duct of this size with assumed turns and fittings will exceed the rated pressure drop.
M1506.3 Exhaust openings.
Air exhaust openings shall terminate not less than 3 feet (914 mm) from property lines; 3 feet (914 mm) from operable and nonoperable openings into
the building and 10 feet (3048 mm) from mechanical air intakes except where the opening is located 3 feet (914 mm) above the air intake. Openings
shall comply with Sections R303.5.2 and R303.6.
DUCT TYPE FLEX DUCT SMOOTH-WALL DUCT
Fan airflow rating (CFM @ 0.25 inch wc )a 50 80 100 125 150 200 250 300 50 80 100 125 150 200 250 300
Diameter (inches)b Maximum length (feet)c, d, e
3 X X X X X X X X 5 X X X X X X X
4 56 4 X X X X X X 114 31 10 X X X X X
5 NL 81 42 16 2 X X X NL 152 91 51 28 4 X X
6 NL NL 158 91 55 18 1 X NL NL NL 168 112 53 25 9
7 NL NL NL NL 161 78 40 19 NL NL NL NL NL 148 88 54
8 and above NL NL NL NL NL 189 111 69 NL NL NL NL NL NL 198 133
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