Double-Wall, Round and Flat Oval Duct

Double-Wall, Flat Oval Duct

For applications in which space restrictions prohibit the use of round duct, McGill AirFlow offers double-wall, flat oval duct in spiral lockseam and longitudinal seam constructions. Each piece is constructed of a solid metal pressure shell and a metal inner liner (either perforated or solid metal) with a layer of insulation sandwiched between.

Flat oval duct provides a more efficient alternative to rectangular duct in applications where space is restricted. McGill AirFlow manufactures flat oval duct with the same techniques used to make round duct. As a result, flat oval duct shares many of the performance characteristics of round duct.

Double-wall, flat oval duct

Spiral lockseam duct is constructed with an interlocking helical seam that runs the length of the duct’s outer pressure shell. As with round spiral lockseam duct, the flat oval type combines efficient performance with a structural strength equal to that of heavier gauges of other types of duct.

Flat oval duct is available with a longitudinal seam construction for applications that require very heavy gauges or large sizes. The longitudinal seam of the duct’s outer pressure shell is solid welded.

Double-Wall, Flat Oval Duct
Available Lengths, Materials, and Thicknesses

ACOUSTI-k27® Duct (spiral lockseam)
Lengths (1)	Materials (2,4)	Thicknesses (3)
1-12 feet	Galvanized Steel	26-18 gauge
	Stainless Steel	26-20 gauge
	Aluminum	0.025-0.063 inch
Longitudinal Seam-k27® Duct (solid welded)
Lengths (1)	Materials (2,4)	Thicknesses (3)
1-6 feet	Galvanized Steel	20-10 gauge
	Stainless Steel	22-10 gauge
	Aluminum	0.040-0.090 inch (3)

(1) Some standard lengths of ACOUSTI-k27 flat oval duct are only available in 6-foot lengths; longer lengths are available on special order. Standard lengths of Longitudinal Seam-k27 duct are 5 and 6 feet.

(2) Double-wall, flat oval duct and fittings are also available in carbon steel, paintable galvanized steel, types 304 and 316 stainless steel, and type 3003-H14 aluminum.

(3) Aluminum double-wall, flat oval duct and fittings are available in larger sizes and greater thicknesses on special order.

(4) SilverGuard™ double-wall, flat oval duct and fittings (pre-coated with an antimicrobial) are available on special order.

Double-Wall, Flat Oval Duct and Fittings—
Available Size Ranges

Minor Axis, Inner Liner (inches)	Major Axis, Inner Liner (inches)
	Spiral Lockseam						Longitudinal Seam
	Minimum			Maximum			Minimum	Maximum
	Insulation Thickness			Insulation Thickness
	1 inch	2 inch	3 inch	1 inch	2 inch	3 inch
3	8	8	8	19	19	17	22	30
4	7	7	7	21	21	21	23	40
5	8	8	8	21	19	19	24	46
6	8	8	8	59	59	59	na	na
7	10	10	na	21	21	na	23	62
8	10	10	11	77	77	74	na	na
9	12	na	na	23	na	na	26	89
10	12	13	13	79	76	73	84	99
11	na	na	na	na	na	na	14	109
12	18	17	17	78	75	75	78	119
14	20	20	20	77	77	74	84	139
16	22	22	29	79	76	76	85	143
18	24	31	31	78	78	75	87	134
20	33	33	na	80	77	na	85	140
22	35	na	na	79	na	na	84	134
24	not available (na)						37	141
26							29	137
28							31	144
30							33	141
32							35	139
34							37	138
36							39	136
38							41	136
40							43	143


	Acoustical Benefits Thermal Benefits Mechanical Benefits

	McGill AirFlow's Double-Wall, Insulated Round and Flat Oval Duct and Fittings: Double-Wall, Round Duct Double-Wall, Round Fittings Double-Wall, Flat Oval Duct Double-Wall, Flat Oval Fittings

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