Duct Caps | McMaster-Carr

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156 Products

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

Rain Caps

Top off vertical duct and exhaust stacks to prevent corrosion and blockages that can disrupt airflow.

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

Corrosion-Resistant 304 Stainless Steel—The most corrosion-resistant metal duct we sell. It won’t rust or degrade in systems that exhaust chemical fumes or vent heat from industrial ovens and dryers.

			Galvanized Steel		Corrosion-Resistant 304 Stainless Steel
Duct Size	ID	Ga.		Each		Each



	3	3"	26	1766K71	000000	———	0


	4	4"	26	1766K72	00000	1767K32	000000
	5	5"	26	1766K73	00000	———	0
	6	6"	26	1766K74	00000	1767K34	00000
	7	7"	26	1766K75	00000	———	0
	8	8"	26	1766K76	00000	1767K36	00000
	9	9"	26	1766K77	00000	———	0
	10	10"	26	1766K78	00000	1767K37	000000
	12	12"	26	1766K79	00000	1767K38	000000

End Caps

Cover unused duct openings to prevent air from leaking, dust from escaping, and debris from entering. 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		Corrosion-Resistant 304 Stainless Steel
	Duct Size	ID	OD	Ga.		Each		Each
Male



		3	—	2 7/8"	26	17135K46	00000	———	0


		4	—	3 7/8"	26	17135K81	0000	———	0
		5	—	4 7/8"	26	17135K82	0000	———	0
		6	—	5 7/8"	26	17135K83	0000	———	0
		7	—	6 7/8"	26	17135K84	00000	———	0
		8	—	7 7/8"	26	17135K85	00000	———	0
		9	—	8 15/16"	26	17135K71	00000	———	0
		10	—	9 7/8"	26	17135K87	00000	———	0
		12	—	11 7/8"	26	17135K88	00000	———	0
		14	—	13 7/8"	26	17135K89	00000	———	0
		16	—	15 7/8"	26	17135K41	00000	———	0


		18	—	17 7/8"	24	17135K42	00000	———	0
		20	—	19 7/8"	24	17135K43	00000	———	0
		22	—	21 7/8"	24	17135K44	00000	———	0
		24	—	23 7/8"	24	17135K45	00000	———	0


		Female



				3	3"	—	26	17135K36	0000	1767K61	000000


				4	4"	—	26	17135K91	0000	1767K62	00000
				5	5"	—	26	17135K92	0000	———	0
				6	6"	—	26	17135K93	0000	1767K64	00000
				7	7"	—	26	17135K94	00000	———	0
				8	8"	—	26	17135K95	00000	1767K66	00000
				9	9"	—	26	17135K96	00000	———	0
				10	10"	—	26	17135K97	00000	1767K68	000000
				12	12"	—	26	17135K98	00000	———	0
				14	14"	—	26	17135K99	00000	———	0
				16	16"	—	26	17135K31	00000	———	0


				18	18"	—	26	17135K32	00000	———	0
				20	20"	—	24	17135K33	00000	———	0
				22	22"	—	24	17135K34	00000	———	0
				24	24"	—	24	17135K35	00000	———	0

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.

End Caps

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

			Galvanized Steel		Corrosion-Resistant 304 Stainless Steel
Duct Size	ID	Ga.		Each		Each



	3	2 7/8"	18	1761K657	000000	———	0


	3	3 1/16"	22	———	0	2538K508	000000
	4	3 7/8"	22	1761K163	00000	2538K679	00000
	5	4 7/8"	22	1761K164	00000	2538K681	00000
	6	5 7/8"	22	1761K165	00000	2538K682	00000
	7	6 7/8"	22	1761K605	00000	2538K729	00000
	8	7 7/8"	22	1761K166	00000	2538K683	00000
	9	8 7/8"	22	1761K606	00000	2538K731	00000
	10	9 7/8"	22	1761K171	00000	2538K684	00000
	12	12"	22	1761K172	00000	2538K685	00000
	14	13 15/16"	20	1761K173	00000	2538K686	00000


	16	16"	20	1761K174	00000	2538K687	00000
	18	17 7/8"	20	1761K658	00000	———	0
	18	17 15/16"	20	———	0	2538K534	00000
	20	19 7/8"	20	1761K659	00000	———	0
	20	19 15/16"	20	———	0	2538K535	00000
	22	21 7/8"	20	1761K661	00000	———	0
	24	23 7/8"	20	1761K662	00000	———	0

Spiral Duct and Fittings

Reinforced with a continuous seam, this duct keeps its shape, even against suction from dust collection systems. On the inside, duct is smooth for efficient airflow. Because of its attractive look, spiral duct is often used for exposed heating and cooling systems.

End Caps

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

		Galvanized Steel			Corrosion-Resistant 304 Stainless Steel
Duct Size	OD	Ga.		Each	Ga.		Each
3	2 7/8"	24	5078K33	000000	24	2561K197	000000
4	3 7/8"	24	5078K35	00000	24	2561K24	00000
5	4 7/8"	24	5078K36	00000	24	2561K198	00000
6	5 7/8"	24	5078K38	00000	24	2561K25	00000
7	6 7/8"	24	5078K358	00000	24	2561K199	00000
8	7 7/8"	24	5078K39	00000	24	2561K26	00000
9	8 7/8"	24	5078K359	00000	24	2561K201	00000
10	9 7/8"	24	5078K41	00000	24	2561K27	00000
12	11 7/8"	24	5078K42	00000	24	2561K202	00000
14	13 7/8"	24	5078K85	00000	24	2561K203	000000
16	15 7/8"	24	5078K86	00000	24	2561K204	000000
18	17 7/8"	22	5078K361	00000	24	2561K205	000000
20	19 7/8"	24	5078K362	00000	24	2561K206	000000
22	21 7/8"	24	5078K363	00000	—	———	0
24	23 7/8"	24	5078K364	00000	—	———	0

Tight-Seal Spiral Duct and Fittings

Gasketed fittings prevent leaks between connections without the need for tape or other sealants. Duct has a continuous seam that reinforces it for strength and long life. The rigid construction keeps its shape, even against suction from dust collectors. Duct is smooth on the inside for efficient airflow. Because of its attractive look, spiral duct is often used for exposed heating and cooling systems.

End Caps

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

		Galvanized Steel with EPDM Gasket
Duct Size	OD	Ga.		Each
4	3 7/8"	24	2226K32	000000
6	5 7/8"	24	2226K33	00000
8	7 7/8"	24	2226K34	00000
10	9 7/8"	24	2226K35	00000
12	11 7/8"	24	2226K36	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.

Rain Caps

Prevent blockages that can disrupt airflow in vertical duct and exhaust stacks. These caps keep water and debris from entering your system.

			PVC
Duct Size	ID	Color		Each



	4	4 1/2"	Gray	2051K8	0000000


	6	6 5/8"	Gray	2051K18	000000
	8	8 5/8"	Gray	2051K38	000000
	10	10 3/4"	Gray	2051K58	000000
	12	12 3/4"	Gray	2051K78	000000
	14	14"	Gray	2051K98	000000

End Caps

			PVC
Duct Size	ID	Color		Each



	4	4 1/2"	Gray	2051K127	000000


	6	6 5/8"	Gray	2051K121	000000
	8	8 5/8"	Gray	2051K122	000000
	10	10 3/4"	Gray	2051K123	000000
	12	12 3/4"	Gray	2051K124	000000
	14	14"	Gray	2051K125	000000

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.

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 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

Expansion Plugs for Conduit

Seal conduit openings to keep water, dirt, and animals from damaging your wiring. When you twist the nut on top of these plugs, a rubber seal expands to close off the end of your conduit. Tie a rope or pull line to the loop at either end of these plugs to hold them in place during installation.

	For Conduit			Material
	Trade Size	ID	Overall Ht.	Seal	Loop	Features		Each
Loop Nut—Plastic Plate



		3/4	0.77" to 1.02"	3 1/4"	Synthetic Rubber	Plastic	Internal Eyebolt	6564N11	00000


		1	0.99" to 1.39"	3 3/4"	Synthetic Rubber	Plastic	Internal Eyebolt	6564N12	0000
		1 1/4	1.16" to 1.51"	3 13/16"	Synthetic Rubber	Plastic	Internal Eyebolt	6564N13	0000
		1 1/2	1.46" to 1.83"	4"	Synthetic Rubber	Plastic	Internal Eyebolt	6564N14	0000
		2	1.83" to 2.39"	4"	Synthetic Rubber	Plastic	Internal Eyebolt	6564N15	0000
		2 1/2	2.4" to 2.99"	7 1/2"	Synthetic Rubber	Plastic	Internal Eyebolt	6564N16	00000
		3	2.92" to 3.45"	7 5/8"	Synthetic Rubber	Plastic	Internal Eyebolt	6564N17	00000
		3 1/2	3.41" to 3.9"	8 3/16"	Synthetic Rubber	Plastic	Internal Eyebolt	6564N18	00000
		4	3.94" to 4.33"	7 1/2"	Synthetic Rubber	Plastic	Internal Eyebolt	6564N19	00000
		5	4.85" to 5.25"	7 5/8"	Synthetic Rubber	Plastic	Internal Eyebolt	6564N21	00000
		6	5.92" to 6.37"	10 5/8"	Synthetic Rubber	Plastic	Internal Eyebolt	6564N22	00000