Duct Caps | McMaster-Carr

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For Conduit ID

156 Products

About Duct Connections

No need for clamps or connectors—duct and fittings press-fit together. Male ends are crimped or tapered, making them slightly smaller than a female end for simple assembly.

Galvanized steel has good corrosion resistance. Aluminum is more lightweight than steel and stainless steel and has good corrosion resistance. 304 stainless steel is more corrosion resistant than steel and aluminum.

Vent Caps

Exhaust Vent

Intake Vent

					Galvanized Steel			Aluminum
Duct Size	Female ID	Male OD	Includes	End Construction	Gauge		Each	Gauge		Each
Exhaust Vent
3	3"	__	Damper	Plain	__	000000	00	30	0000000	000000
4	4"	__	Damper	Plain	30	00000000	000000	30	0000000	00000
5	5"	__	Damper	Plain	30	00000000	00000	__	000000	00
6	6"	__	Damper	Plain	30	00000000	00000	22	0000000	00000
7	7"	__	Damper	Plain	30	00000000	00000	__	000000	00
8	8"	__	Damper	Plain	30	00000000	00000	22	0000000	000000
Intake Vent
4	__	3 7/8"	Screen	Crimped	30	00000000	00000	__	000000	00
5	__	4 7/8"	Screen	Crimped	30	00000000	00000	__	000000	00
6	__	5 7/8"	Screen	Crimped	30	00000000	00000	__	000000	00
7	__	6 7/8"	Screen	Crimped	30	00000000	00000	__	000000	00
8	__	7 7/8"	Screen	Crimped	30	00000000	00000	__	000000	00

Rain Caps

Galvanized Steel

304 Stainless Steel

			Galvanized Steel			304 Stainless Steel
Duct Size	Female ID	End Construction	Gauge		Each	Gauge		Each
3	3"	Plain	26	0000000	000000	__	000000	00
4	4"	Plain	26	0000000	00000	26	0000000	000000
5	5"	Plain	26	0000000	00000	__	000000	00
6	6"	Plain	26	0000000	00000	26	0000000	00000
7	7"	Plain	26	0000000	00000	__	000000	00
8	8"	Plain	26	0000000	00000	26	0000000	00000
9	9"	Plain	26	0000000	00000	__	000000	00
10	10"	Plain	26	0000000	00000	26	0000000	000000
12	12"	Plain	26	0000000	00000	26	0000000	000000

End Caps

Female

Male

					Galvanized Steel		304 Stainless Steel
Duct Size	Female ID	Male OD	Gauge	End Construction		Each		Each
Female
3	3"	__	26	Plain	00000000	00000	0000000	000000
4	4"	__	26	Plain	00000000	0000	0000000	00000
5	5"	__	26	Plain	00000000	0000	000000	00
6	6"	__	26	Plain	00000000	0000	0000000	00000
7	7"	__	26	Plain	00000000	00000	000000	00
8	8"	__	26	Plain	00000000	00000	0000000	00000
9	9"	__	26	Plain	00000000	00000	000000	00
10	10"	__	26	Plain	00000000	00000	0000000	000000
12	12"	__	26	Plain	00000000	00000	000000	00
14	14"	__	26	Plain	00000000	00000	000000	00
16	16"	__	26	Plain	00000000	00000	000000	00
18	18"	__	26	Plain	00000000	00000	000000	00
20	20"	__	24	Plain	00000000	00000	000000	00
22	22"	__	24	Plain	00000000	00000	000000	00
24	24"	__	24	Plain	00000000	00000	000000	00
Male
3	__	2 7/8"	26	Crimped	00000000	0000	000000	00
4	__	3 7/8"	26	Crimped	00000000	0000	000000	00
5	__	4 7/8"	26	Crimped	00000000	0000	000000	00
6	__	5 7/8"	26	Crimped	00000000	0000	000000	00
7	__	6 7/8"	26	Crimped	00000000	00000	000000	00
8	__	7 7/8"	26	Crimped	00000000	00000	000000	00
9	__	8 15/16"	26	Crimped	00000000	00000	000000	00
10	__	9 7/8"	26	Crimped	00000000	00000	000000	00
12	__	11 7/8"	26	Crimped	00000000	00000	000000	00
14	__	13 7/8"	26	Crimped	00000000	00000	000000	00
16	__	15 7/8"	26	Crimped	00000000	00000	000000	00
18	__	17 7/8"	24	Crimped	00000000	00000	000000	00
20	__	19 7/8"	24	Crimped	00000000	00000	000000	00
22	__	21 7/8"	24	Crimped	00000000	00000	000000	00
24	__	23 7/8"	24	Crimped	00000000	00000	000000	00

Quick-Disconnect Duct and Fittings

Join duct and fittings with quick-release clamps for faster disassembly and cleanout than other duct systems.

Galvanized steel has good corrosion resistance. 304 stainless steel is the most corrosion resistant.

End Caps

				Galvanized Steel		304 Stainless Steel
Duct Size	ID	Gauge	End Construction		Each		Each
3	2 7/8"	18	Rolled	00000000	000000	000000	00
3	3 1/16"	22	Rolled	000000	00	00000000	000000
4	3 7/8"	22	Rolled	00000000	00000	00000000	00000
5	4 7/8"	22	Rolled	00000000	00000	00000000	00000
6	5 7/8"	22	Rolled	00000000	00000	00000000	00000
7	6 7/8"	22	Rolled	00000000	00000	00000000	00000
8	7 7/8"	22	Rolled	00000000	00000	00000000	00000
9	8 7/8"	22	Rolled	00000000	00000	00000000	00000
10	9 7/8"	22	Rolled	00000000	00000	00000000	00000
12	12"	22	Rolled	00000000	00000	00000000	00000
14	13 15/16"	20	Rolled	00000000	00000	00000000	00000
16	16"	20	Rolled	00000000	00000	00000000	000000
18	17 7/8"	20	Rolled	00000000	00000	000000	00
18	17 15/16"	20	Rolled	000000	00	00000000	000000
20	19 7/8"	20	Rolled	00000000	00000	000000	00
20	19 15/16"	20	Rolled	000000	00	00000000	000000
22	21 7/8"	20	Rolled	00000000	00000	000000	00
24	23 7/8"	20	Rolled	00000000	00000	000000	00

Crush-Resistant Spiral Duct and Fittings

A spiral seam makes this duct strong and rigid. Fittings have male ends with a slightly smaller diameter to press-fit into duct.

Galvanized steel has good corrosion resistance. 304 stainless steel is more corrosion resistant than steel.

End Caps

				Galvanized Steel		304 Stainless Steel
Duct Size	Male OD	Gauge	End Construction		Each		Each
Male
3	2 7/8"	24	Spiral	0000000	000000	00000000	000000
4	3 7/8"	24	Plain	000000	00	0000000	00000
4	3 7/8"	24	Spiral	0000000	00000	000000	00
5	4 7/8"	24	Spiral	0000000	00000	00000000	00000
6	5 7/8"	24	Plain	000000	00	0000000	00000
6	5 7/8"	24	Spiral	0000000	00000	000000	00
7	6 7/8"	24	Spiral	00000000	00000	00000000	00000
8	7 7/8"	24	Plain	000000	00	0000000	00000
8	7 7/8"	24	Spiral	0000000	00000	000000	00
9	8 7/8"	24	Spiral	00000000	00000	00000000	00000
10	9 7/8"	24	Plain	000000	00	0000000	00000
10	9 7/8"	24	Spiral	0000000	00000	000000	00
12	11 7/8"	24	Spiral	0000000	00000	00000000	00000
14	13 7/8"	24	Spiral	0000000	00000	00000000	000000
16	15 7/8"	24	Spiral	0000000	00000	00000000	000000
18	17 7/8"	22	Spiral	00000000	00000	000000	00
18	17 7/8"	24	Spiral	000000	00	00000000	000000
20	19 7/8"	24	Spiral	00000000	00000	00000000	000000
22	21 7/8"	24	Spiral	00000000	00000	000000	00
24	23 7/8"	24	Spiral	00000000	00000	000000	00

Chemical-Resistant Duct and Fittings

Made of PVC plastic to withstand acids, alkalies, salts, and other corrosive vapors and fumes. Use PVC pipe cement (not included) to secure components. Fittings have female ends with a slightly larger diameter to press-fit over duct.

Rain Caps

			PVC Plastic
Duct Size	Female ID	Color		Each
4	4 1/2"	Gray	000000	0000000
6	6 5/8"	Gray	0000000	000000
8	8 5/8"	Gray	0000000	000000
10	10 3/4"	Gray	0000000	000000
12	12 3/4"	Gray	0000000	000000
14	14"	Gray	0000000	000000

End Caps

			PVC Plastic
Duct Size	Female ID	Color		Each
4	4 1/2"	Gray	00000000	000000
6	6 5/8"	Gray	00000000	000000
8	8 5/8"	Gray	00000000	000000
10	10 3/4"	Gray	00000000	000000
12	12 3/4"	Gray	00000000	000000
14	14"	Gray	00000000	000000

Sure-Seal Spiral Duct and Fittings

Fittings have gaskets which create a tight seal—you don't need to seal joints with coating or tape. Fittings have male ends with a slightly smaller diameter to press-fit into duct. These duct and fittings are compatible with Crush-Resistant Spiral Duct and Fittings.

End Caps

				Galvanized Steel
Duct Size	Male OD	Gauge	Gasket Material		Each
4	3 7/8"	24	EPDM Rubber	0000000	000000
6	5 7/8"	24	EPDM Rubber	0000000	00000
8	7 7/8"	24	EPDM Rubber	0000000	00000
10	9 7/8"	24	EPDM Rubber	0000000	00000
12	11 7/8"	24	EPDM Rubber	0000000	00000

Rectangular Duct and Fittings

Often used in tight spaces, such as in walls and ceilings, rectangular duct allows you to select larger sizes without increasing duct height. Duct and fittings have interconnecting ends that lock together with brackets.

For technical drawings and 3-D models, click on a part number.

End Caps

			Galvanized Steel
Wd.	Ht.	Gauge		Each
8"	8"	28	0000000	00000
10"	8"	28	0000000	0000
12"	8"	28	0000000	00000
14"	8"	28	0000000	00000
16"	8"	26	0000000	00000
20"	8"	26	0000000	00000
24"	8"	26	0000000	00000

Sloped Roof Vent Caps

Cover external vents to reduce downdrafts and prevent obstructions from entering the vent.

For Duct									Painted Steel
Ht.	Wd.	Dia.	Ht.	Wd.	Lg.	Gauge	Features	Includes		Each
For Rectangular and Round Duct
10"	3 1/4"	8"	6 5/8"	14 1/4"	18 3/4"	24	Bird Screen	Backdraft Damper	0000000	000000

Wall Vent Caps

Cover external vents to reduce downdrafts and prevent obstructions from entering the vent.

For Duct								Mounting		Painted Steel
Ht.	Wd.	Ht.	Wd.	Lg.	Gauge	Features	Includes	Fasteners Included	Hole Dia.		Each
For Rectangular Duct
10"	3 1/4"	5 5/8"	12 3/4"	8 7/8"	24	Bird Screen	Backdraft Damper	No	3/16"	0000000	000000

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	O'all Ht.	Seal	Loop	Features		Each
Loop Nut—Plastic Plate
3/4	0.77"-1.02"	3 1/4"	Synthetic Rubber	Plastic	Internal Eyebolt	0000000	00000
1	0.99"-1.39"	3 3/4"	Synthetic Rubber	Plastic	Internal Eyebolt	0000000	0000
1 1/4	1.16"-1.51"	3 13/16"	Synthetic Rubber	Plastic	Internal Eyebolt	0000000	0000
1 1/2	1.46"-1.83"	4"	Synthetic Rubber	Plastic	Internal Eyebolt	0000000	0000
2	1.83"-2.39"	4"	Synthetic Rubber	Plastic	Internal Eyebolt	0000000	0000
2 1/2	2.4"-2.99"	7 1/2"	Synthetic Rubber	Plastic	Internal Eyebolt	0000000	00000
3	2.92"-3.45"	7 5/8"	Synthetic Rubber	Plastic	Internal Eyebolt	0000000	00000
3 1/2	3.41"-3.9"	8 3/16"	Synthetic Rubber	Plastic	Internal Eyebolt	0000000	00000
4	3.94"-4.33"	7 1/2"	Synthetic Rubber	Plastic	Internal Eyebolt	0000000	00000
5	4.85"-5 1/4"	7 5/8"	Synthetic Rubber	Plastic	Internal Eyebolt	0000000	00000
6	5.92"-6.37"	10 5/8"	Synthetic Rubber	Plastic	Internal Eyebolt	0000000	00000

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About Duct Connections

Standard Duct and Fittings

Quick-Disconnect Duct and Fittings

Crush-Resistant Spiral Duct and Fittings

Chemical-Resistant Duct and Fittings

Sure-Seal Spiral Duct and Fittings

Rectangular Duct and Fittings

Sloped Roof Vent Caps

Wall Vent Caps

Expansion Plugs for Conduit