Square Duct | McMaster-Carr

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96 Products

Rectangular Duct and Fittings

Maximize the space in close quarters, such as inside walls and ceilings. As rectangular duct sizes increase, they get wider but not taller. This shape is most often used for heating and cooling inside buildings. Components connect with brackets.

Duct

Pair with compatible fittings and accessories.

Galvanized Steel—Corrosion resistant and affordable, galvanized steel is the most commonly used ductwork material.

					Galvanized Steel
Wd.	Ht.	Lg., ft.	Ga.	Includes		Each



	8"	8"	4	28	Two Drive Brackets, Two S-Brackets	1964K81	000000


	10"	8"	4	28	Two Drive Brackets, Two S-Brackets	1964K82	00000
	12"	8"	4	28	Two Drive Brackets, Two S-Brackets	1964K83	00000
	14"	8"	4	28	Two Drive Brackets, Two S-Brackets	1964K84	00000
	16"	8"	4	26	Two Drive Brackets, Two S-Brackets	1964K85	00000
	20"	8"	4	26	Two Drive Brackets, Two S-Brackets	1964K86	000000
	24"	8"	4	26	Two Drive Brackets, Two S-Brackets	1964K87	000000

Brackets

S-Bracket

Drive Bracket

Securely connect rectangular duct and fittings. Brackets can be cut to length. Also known as cleats.

Galvanized Steel—Corrosion resistant and affordable, galvanized steel is the most commonly used ductwork material.

S-Bracket—Connect the long sides of duct.

Drive Bracket— Connect the short sides of duct.

					Galvanized Steel
Bracket Type	Wd.	Ht.	Lg., ft.	Ga.		Each



	S	1 1/16"	1/4"	5	26	1964K92	00000


	Drive	1 1/8"	1/8"	5	26	1964K94	0000

90° Elbow Connectors

Horizontal Elbow

Vertical Elbow

Change the direction of airflow when joining lengths of duct.

Galvanized Steel—Corrosion resistant and affordable, galvanized steel is the most commonly used ductwork material.

				Galvanized Steel
	Wd.	Ht.	Ga.		Each
Horizontal Elbow



		8"	8"	28	1964K31	000000


		10"	8"	28	1964K32	00000
		12"	8"	28	1964K33	00000
		14"	8"	28	1964K34	00000
		16"	8"	26	1964K35	00000
		20"	8"	26	1964K36	00000
		24"	8"	26	1964K37	00000


		Vertical Elbow



				8"	8"	28	1964K51	00000


				10"	8"	28	1964K52	00000
				12"	8"	28	1964K53	00000
				14"	8"	28	1964K54	00000
				16"	8"	26	1964K55	00000
				20"	8"	26	1964K56	00000
				24"	8"	26	1964K57	00000

45° Elbow Connectors

Horizontal Elbow

Vertical Elbow

Change the direction of airflow when joining lengths of duct.

Galvanized Steel—Corrosion resistant and affordable, galvanized steel is the most commonly used ductwork material.

				Galvanized Steel
	Wd.	Ht.	Ga.		Each
Horizontal Elbow



		8"	8"	28	1964K21	000000


		10"	8"	28	1964K22	00000
		12"	8"	28	1964K23	00000
		14"	8"	28	1964K24	00000


		Vertical Elbow



				8"	8"	28	1964K41	00000


				10"	8"	28	1964K42	00000
				12"	8"	28	1964K43	00000
				14"	8"	28	1964K44	00000

Straight Reducers

Shown Installed

Image of Product. Front orientation. Duct and Fittings. Rectangular Duct and Fittings, Straight Reducers.

Transition between ducts of different sizes. These reducers decrease duct width by 2". Cut a hole in the smaller duct to fit the reducer and secure it with tapping screws.

Galvanized Steel—Corrosion resistant and affordable, galvanized steel is the most commonly used ductwork material.

			Galvanized Steel
Wd.	Ht.	Ga.		Each



	2"	8"	28	1964K12	000000

Straight Collars

Add a branch to an existing line of rectangular duct. Cut a hole in the duct, attach the collar by bending the tabs, and connect another piece of duct.

Galvanized Steel—Corrosion resistant and affordable, galvanized steel is the most commonly used ductwork material.

			Galvanized Steel
Wd.	Ht.	Ga.		Each



	8"	8"	28	1964K61	000000


	10"	8"	28	1964K62	00000
	12"	8"	28	1964K63	00000
	14"	8"	28	1964K64	00000
	16"	8"	26	1964K65	00000
	24"	8"	26	1964K67	00000

End Caps

Cover unused duct openings to prevent air leaks. End caps are often used to seal duct after changes to your system or equipment. To make modifications or expand your line, remove the cap.

Galvanized Steel—Corrosion resistant and affordable, galvanized steel is the most commonly used ductwork material.

			Galvanized Steel
Wd.	Ht.	Ga.		Each



	8"	8"	28	1964K71	00000


	10"	8"	28	1964K72	0000
	12"	8"	28	1964K73	00000
	14"	8"	28	1964K74	00000
	16"	8"	26	1964K75	00000
	20"	8"	26	1964K76	00000
	24"	8"	26	1964K77	00000

Duct Turning Vanes

Shown Cut and Assembled

Turning Vanes—Guide air smoothly around sharp bends. These turning vanes improve airflow efficiency by reducing turbulence and pressure loss. Cut vanes to size and pair with rails. Mount assembled vanes inside duct using tapping screws.

Turning Vane Rails—Mounting tabs hold vanes in place. Cut rails to length.

						Galvanized Steel
	Wd.	Ht.	Lg., ft.	Rail Mounting Tab Spacing	Ga.		Each
Turning Vanes



		2 7/8"	1"	6	—	26	1000K5	000000


		5 5/8"	1 7/8"	6	—	24	1000K6	00000


		Turning Vane Rails



				4 1/2"	—	6	2 1/2"	24	1000K2	00000


				7 3/8"	—	6	3 1/4"	24	1000K3	00000

Quick-Disconnect Duct and Fittings

The fastest ductwork to disassemble for dust collection and other frequently cleaned systems. Join sections with quick-release clamps that open and close with a flip of the latch. Since you don’t need screws, welds, or tools, the installation time is half that of other duct types.

Intake Hoods

Capture air, vapors, and fumes and funnel them away. These hoods direct contaminants into your duct system and away from workers and machines.

Galvanized Steel—Corrosion resistant and affordable, galvanized steel is the most commonly used ductwork material.

			Galvanized Steel
Duct Size	ID	Ga.		Each



	4	3 7/8"	22	1761K77	0000000


	5	4 7/8"	22	1761K78	000000
	6	5 7/8"	22	1761K79	000000
	8	7 7/8"	22	1761K81	000000
	10	9 7/8"	22	1761K82	000000

Airflow Dampers for Square Duct

Direct airflow to different zones in your facility or regulate the amount of outside air introduced to your system. Turn the lever on these dampers to adjust the blades.

Galvanized Steel—Strong and corrosion resistant, galvanized steel is the most commonly used ductwork material.

For Duct		Overall					Galvanized Steel
Ht.	Wd.	Ht.	Wd.	Dp.	Ga.	Gasket Material		Each
12"	12"	11 3/4"	11 3/4"	5 1/2"	16	Vinyl Plastic	2041K12	0000000
14"	14"	13 3/4"	13 3/4"	5 1/2"	16	Vinyl Plastic	2041K13	000000
16"	16"	15 3/4"	15 3/4"	5 1/2"	16	Vinyl Plastic	2041K14	000000
24"	24"	23 3/4"	23 3/4"	5 1/2"	16	Vinyl Plastic	2041K22	000000
36"	36"	35 3/4"	35 3/4"	5 1/2"	16	Vinyl Plastic	2041K27	000000

Duct Fire Dampers

In case of a fire, these dampers shut automatically to stop airflow. They have a fusible link that melts at 165° F, releasing a spring to close the blade. Dampers meet UL 555 fire safety standards to help prevent the spread of fire for 1_1/2hours. They are undersized to fit inside duct.

For Square Duct

Galvanized Steel—Strong and corrosion resistant, galvanized steel is the most commonly used ductwork material.

For Duct		Overall						Galvanized Steel
Ht.	Wd.	Ht.	Wd.	Dp.	Fire Safety Std.	Fusible Link Melting Temp., ° F	Ga.		Each
8"	8"	7 3/4"	7 3/4"	4 7/8"	UL 555	165	22	2263K29	000000
12"	12"	11 3/4"	11 3/4"	4 7/8"	UL 555	165	22	2263K88	00000
14"	14"	13 3/4"	13 3/4"	4 7/8"	UL 555	165	22	2263K91	00000
18"	18"	17 3/4"	17 3/4"	4 7/8"	UL 555	165	22	2263K93	000000
24"	24"	23 3/4"	23 3/4"	4 7/8"	UL 555	165	22	2263K97	000000

Fusible Links

		Each
Replacement Fusible Link with 165° F Melting Temperature	19215K32	00000
Fusible Link with 212° F Melting Temperature	19215K96	0000
Fusible Link with 386° F Melting Temperature	19215K19	00000

Turning Vanes for Rectangular Duct

Shown Cut and Assembled

Turning Vanes

Turning Vane Rails

Guide air smoothly around sharp bends in rectangular duct. Turning vanes improve airflow efficiency by reducing turbulence and pressure loss. Cut vanes and rails to size, then mount the vanes between two rails. Rails have mounting tabs to hold vanes. Mount inside duct using tapping screws (not included).

Galvanized Steel—Corrosion resistant and affordable, galvanized steel is the most commonly used ductwork material.

						Galvanized Steel
	Wd.	Ht.	Lg., ft.	Rail Mounting Tab Spacing	Ga.		Each
Turning Vanes



		2 7/8"	1"	6	—	26	1000K5	000000


		5 5/8"	1 7/8"	6	—	24	1000K6	00000


		Turning Vane Rails



				4 1/2"	—	6	2 1/2"	24	1000K2	00000


				7 3/8"	—	6	3 1/4"	24	1000K3	00000

Standard Duct and Fittings

Deliver air for a range of HVAC applications, including exhaust and dust collection. Our basic duct, the round shape creates smoother, more efficient airflow than rectangular and oval duct. The male end is slightly smaller than the female, so sections join without clamps or tools.

Vent Caps


Exhaust Vent	Intake Vent

Cover vents with caps that let air in or out.

Exhaust Vent—A built-in damper allows air to escape while blocking backdrafts, rain, and snow.

Intake Vent—Only fresh air enters though the screen—no debris or pests allowed.

Galvanized Steel—Corrosion resistant and affordable, galvanized steel is the most commonly used ductwork material.

Lightweight Aluminum—One-third the weight of steel, aluminum ductwork is easier to handle during installation. Like galvanized steel, it resists rust in wet environments but won’t last as long.

							Galvanized Steel		Lightweight Aluminum
	Duct Size	ID	OD	Ga.	Features	Includes		Each		Each
Exhaust Vent



		3	3"	—	30	—	Backdraft Damper	———	0	1773K61	000000


		4	4"	—	30	—	Backdraft Damper	1766K484	000000	1773K62	00000
		5	5"	—	30	—	Backdraft Damper	1766K485	00000	———	0
		6	6"	—	30	—	Backdraft Damper	1766K492	00000	———	0
		6	6"	—	22	—	Backdraft Damper	———	0	1773K63	00000
		7	7"	—	30	—	Backdraft Damper	1766K486	00000	———	0
		8	8"	—	30	—	Backdraft Damper	1766K493	00000	———	0
		8	8"	—	22	—	Backdraft Damper	———	0	1773K64	000000


		Intake Vent



				4	—	3 7/8"	30	Bird Screen	—	1766K481	00000	———	0


				5	—	4 7/8"	30	Bird Screen	—	1766K482	00000	———	0
				6	—	5 7/8"	30	Bird Screen	—	1766K497	00000	———	0
				7	—	6 7/8"	30	Bird Screen	—	1766K483	00000	———	0
				8	—	7 7/8"	30	Bird Screen	—	1766K498	00000	———	0

90° Elbow Register Boots

Create an angled airflow path from duct to vents or registers. These boots are commonly used with heating and cooling systems to deliver air through walls and ceilings.

Galvanized Steel—Corrosion resistant and affordable, galvanized steel is the most commonly used ductwork material.

		Opening			Galvanized Steel
Duct Size	ID	Wd.	Lg.	Ga.		Each



	6	6"	2 1/4"	10"	30	1844K14	000000


	6	6"	2 1/4"	12"	30	1844K15	00000
	6	6"	4"	10"	30	1844K17	00000
	6	6"	4"	12"	30	1844K21	00000

Straight Register Boots

Direct air from duct to vents or registers. These boots are commonly used with heating and cooling systems to deliver air through walls and ceilings.

Galvanized Steel—Corrosion resistant and affordable, galvanized steel is the most commonly used ductwork material.

		Opening			Galvanized Steel
Duct Size	ID	Wd.	Lg.	Ga.		Each



	6	6"	2 1/4"	10"	30	1844K34	000000


	6	6"	2 1/4"	12"	30	1844K35	00000
	6	6"	4"	10"	30	1844K37	00000
	6	6"	4"	12"	30	1844K41	00000

Chemical-Resistant Duct and Fittings

Chemicals can eat away at most metal duct, but not this PVC system. It’s often used to exhaust corrosive gases, vapors, and fumes. Components press-fit together and secure with PVC pipe cement.

Intake Hoods

Capture air, vapors, and fumes and funnel them away. These hoods direct contaminants into your duct system and away from workers and machines.

			PVC
Duct Size	ID	Color		Each



	4	4 1/2"	Gray	2051K873	0000000


	6	6 5/8"	Gray	2051K874	000000
	8	8 5/8"	Gray	2051K875	000000
	10	10 3/4"	Gray	2051K876	000000
	12	12 3/4"	Gray	2051K877	000000

Duct Vent Caps


Wall Mount	Sloped Roof Mount

Cover wall and roof vents to prevent cold air and debris from entering your system. These caps have damper to reduce backdrafts and a screen that blocks birds from sneaking in.

Painted Steel—Strong for a long life, these caps have a black finish to prevent rust.

	For Duct						Mounting			Painted Steel
	Ht.	Wd.	Dia.	Ht.	Wd.	Lg.	Fasteners Included	Hole Dia.	Color		Each
Wall Mount







				For Rectangular Duct

				10"	3 1/4"	—	5 5/8"	12 3/4"	8 7/8"	No	3/16"	Black	6904K36	000000


				Sloped Roof Mount







								For Rectangular and Round Duct

								10"	3 1/4"	8"	6 5/8"	14 1/4"	18 3/4"	—	—	Black	6904K34	00000