Steel Duct Reducers | McMaster-Carr

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204 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.

Straight Reducers

Transition between duct of different diameters. Reducers also join larger duct with smaller duct that connects to equipment.

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.

	Duct Size		ID		OD		Galvanized Steel			Corrosion-Resistant 304 Stainless Steel
	(A)	(B)	(A)	(B)	(A)	(B)	Ga.		Each	Ga.		Each
Female × Male



		4	3	4"	—	—	2 7/8"	—	———	0	26	1767K81	000000


		4	3	4"	—	—	2 15/16"	26	2013K16	000000	—	———	0
		5	4	5"	—	—	3 7/8"	26	2013K14	00000	—	———	0
		6	4	6"	—	—	3 7/8"	—	———	0	26	1767K82	00000
		6	4	6"	—	—	3 15/16"	26	2013K17	00000	—	———	0
		6	5	6"	—	—	4 7/8"	26	2013K15	00000	—	———	0
		7	6	7"	—	—	5 7/8"	26	2013K21	00000	—	———	0
		8	4	8"	—	—	3 7/8"	—	———	0	26	1767K83	00000
		8	6	8"	—	—	5 7/8"	—	———	0	26	1767K84	00000
		8	6	8"	—	—	5 15/16"	26	2013K18	00000	—	———	0
		8	7	8"	—	—	6 7/8"	26	2013K26	00000	—	———	0


		9	8	9"	—	—	7 15/16"	26	2013K19	00000	—	———	0
		10	6	10"	—	—	5 7/8"	26	2013K24	00000	—	———	0
		10	7	10"	—	—	6 7/8"	26	2013K28	00000	—	———	0
		10	8	10"	—	—	7 7/8"	26	2013K32	00000	—	———	0
		12	6	12"	—	—	5 7/8"	26	2013K25	00000	—	———	0
		12	7	12"	—	—	6 7/8"	26	2013K29	00000	—	———	0
		12	8	12"	—	—	7 7/8"	26	2013K33	00000	24	1767K313	000000
		12	10	12"	—	—	9 7/8"	26	2013K36	00000	—	———	0
		14	10	14"	—	—	9 7/8"	22	2013K704	00000	24	1767K314	000000
		14	12	14"	—	—	11 7/8"	22	2013K705	00000	—	———	0


		16	12	16"	—	—	11 7/8"	22	2013K706	00000	24	1767K315	000000
		16	14	16"	—	—	13 7/8"	22	2013K707	00000	—	———	0
		18	14	18"	—	—	13 7/8"	22	2013K708	00000	24	1767K316	000000
		18	16	18"	—	—	15 7/8"	22	2013K709	00000	—	———	0
		20	16	20"	—	—	15 7/8"	24	2013K714	00000	24	1767K317	000000
		22	18	22"	—	—	17 7/8"	24	2013K715	000000	—	———	0
		24	20	24"	—	—	19 7/8"	24	2013K716	000000	—	———	0


		Male × Female



				4	3	—	3"	3 7/8"	—	24	2013K711	00000	—	———	0


				5	4	—	4"	4 7/8"	—	24	2013K712	00000	—	———	0
				6	4	—	4"	5 7/8"	—	26	2013K57	00000	—	———	0
				7	6	—	6"	6 7/8"	—	26	2013K41	00000	—	———	0
				8	6	—	6"	7 7/8"	—	26	2013K42	00000	—	———	0
				8	7	—	7"	7 7/8"	—	26	2013K46	00000	—	———	0
				10	6	—	6"	9 7/8"	—	26	2013K44	00000	—	———	0
				10	8	—	8"	9 7/8"	—	26	2013K52	00000	—	———	0
				12	6	—	6"	11 7/8"	—	26	2013K45	00000	—	———	0
				12	8	—	8"	11 7/8"	—	26	2013K53	00000	—	———	0
				12	10	—	10"	11 7/8"	—	26	2013K56	00000	—	———	0


				14	10	—	10"	13 7/8"	—	28	2013K59	00000	—	———	0
				14	12	—	12"	13 7/8"	—	28	2013K61	00000	—	———	0
				16	12	—	12"	15 7/8"	—	26	2013K62	00000	—	———	0
				16	14	—	14"	15 7/8"	—	28	2013K63	00000	—	———	0
				18	14	—	14"	17 7/8"	—	24	2013K713	00000	—	———	0
				18	16	—	16"	17 7/8"	—	26	2013K64	00000	—	———	0
20				18	—	18"	19 15/16"	—	24	2013K701	00000	—	———	0
22	20			—	20"	21 15/16"	—	24	2013K702	00000	—	———	0
24	22			—	22"	23 15/16"	—	24	2013K703	00000	—	———	0

Tee Reducers

Connect duct of different diameters to split or merge airflow.

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

	Duct Size				OD		Galvanized Steel
	(A)	(B)	(C)	ID (A)	(B)	(C)	Ga.		Each
Female × Male × Male



		4	3	4	4"	2 7/8"	3 7/8"	26	1766K626	000000


		5	3	5	5"	2 7/8"	4 7/8"	26	1766K69	00000
		6	3	6	6"	2 7/8"	5 7/8"	26	1766K64	00000
		6	4	6	6"	3 7/8"	5 7/8"	26	1766K66	00000
		8	6	6	8"	5 7/8"	5 7/8"	24	1766K217	000000
		10	8	8	10"	7 7/8"	7 7/8"	24	1766K218	000000
		12	8	8	12"	7 7/8"	7 7/8"	24	1766K219	000000

45° Wye Reducers


Female × Male × Male	Male × Female × Female

Connect duct of different diameters to split or merge airflow more gradually than tees. With less abrupt changes in direction, wyes reduce turbulence for smoother flow.

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

	Duct Size			ID			OD			Galvanized Steel
	(A)	(B)	(C)	(A)	(B)	(C)	(A)	(B)	(C)	Ga.		Each
Female × Male × Male



		12	10	10	12"	—	—	—	9 7/8"	9 7/8"	28	1766K845	0000000


		14	10	10	14"	—	—	—	9 7/8"	9 7/8"	28	1766K846	000000
		16	12	12	16"	—	—	—	11 7/8"	11 7/8"	26	1766K847	000000
		16	14	14	16"	—	—	—	13 7/8"	13 7/8"	26	1766K848	000000


		Male × Female × Female



				4	3	3	—	3"	3"	3 7/8"	—	—	26	1766K861	00000


				5	3	4	—	3"	4"	4 7/8"	—	—	26	1766K862	00000
				5	3	5	—	3"	5"	4 7/8"	—	—	26	1766K866	00000
				6	3	4	—	3"	4"	5 7/8"	—	—	26	1766K867	00000
				6	4	4	—	4"	4"	5 7/8"	—	—	26	1766K868	00000
				6	4	5	—	4"	5"	5 7/8"	—	—	26	1766K863	00000
				7	5	6	—	5"	6"	6 7/8"	—	—	26	1766K864	00000
				8	6	6	—	6"	6"	7 7/8"	—	—	26	1766K865	00000
				10	8	8	—	8"	8"	9 7/8"	—	—	26	1766K869	000000
				12	8	8	—	8"	8"	11 7/8"	—	—	26	1766K843	000000

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.

Straight Reducers

Transition between duct of different diameters. Reducers also join larger duct with smaller duct that connects to equipment.

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

Chemical-Resistant PVC-Coated Steel—This duct combines the strength of steel with the chemical resistance of plastic. More economical than 304 stainless steel and stronger than PVC, it’s often used to exhaust corrosive gases, vapors, and fumes.

Duct Size		OD		Galvanized Steel			Chemical-Resistant PVC-Coated Steel			Corrosion-Resistant 304 Stainless Steel
(A)	(B)	(A)	(B)	Ga.		Each	Ga.		Each	Ga.		Each
4	3	3 7/8"	2 7/8"	24	5078K56	000000	—	———	0	24	2561K125	000000
5	4	4 7/8"	3 7/8"	24	5078K57	00000	20	1889K372	000000	24	2561K126	00000
6	4	5 7/8"	3 7/8"	24	5078K59	00000	20	1889K381	00000	20	2561K28	00000
6	5	5 7/8"	4 7/8"	24	5078K63	00000	20	1889K382	00000	24	2561K127	000000
7	6	6 7/8"	5 7/8"	24	5078K334	00000	20	1889K374	00000	24	2561K128	000000
8	6	7 7/8"	5 7/8"	24	5078K62	00000	20	1889K383	00000	20	2561K29	000000
8	7	7 7/8"	6 7/8"	24	5078K335	00000	20	1889K384	00000	24	2561K129	000000
9	8	8 7/8"	7 7/8"	24	5078K336	00000	20	1889K376	00000	24	2561K131	000000
10	6	9 7/8"	5 7/8"	24	5078K61	00000	—	———	0	20	2561K31	000000
10	8	9 7/8"	7 7/8"	24	5078K65	00000	20	1889K385	000000	20	2561K32	000000
10	9	9 7/8"	8 7/8"	24	5078K337	00000	20	1889K386	000000	—	———	0
12	6	11 7/8"	5 7/8"	24	5078K66	00000	—	———	0	—	———	0
12	8	11 7/8"	7 7/8"	24	5078K68	00000	—	———	0	—	———	0
12	10	11 7/8"	9 7/8"	24	5078K69	00000	20	1889K387	000000	24	2561K132	000000
14	12	13 7/8"	11 7/8"	24	5078K91	00000	—	———	0	24	2561K133	000000
16	14	15 7/8"	13 7/8"	24	5078K92	00000	—	———	0	24	2561K134	000000
18	16	17 7/8"	15 7/8"	22	5078K131	000000	—	———	0	24	2561K135	000000
20	18	19 7/8"	17 7/8"	24	5078K132	000000	—	———	0	24	2561K136	000000
22	20	21 7/8"	19 7/8"	24	5078K133	000000	—	———	0	—	———	0
24	22	23 7/8"	21 7/8"	24	5078K134	000000	—	———	0	—	———	0

Tee Reducers

Connect duct of different diameters to split or merge airflow.

Duct Size			OD			Chemical-Resistant PVC-Coated Steel
(A)	(B)	(C)	(A)	(B)	(C)	Ga.		Each
6	4	6	5 7/8"	3 7/8"	5 7/8"	24	1889K323	000000
8	6	8	7 7/8"	5 7/8"	7 7/8"	24	1889K325	000000
10	8	10	9 7/8"	7 7/8"	9 7/8"	24	1889K327	000000
12	8	12	11 7/8"	7 7/8"	11 7/8"	24	1889K329	000000

45° Wye Reducers

Connect duct of different diameters to split or merge airflow more gradually than tees. With less abrupt changes in direction, wyes reduce turbulence for smoother flow.

Duct Size			OD			Chemical-Resistant PVC-Coated Steel
(A)	(B)	(C)	(A)	(B)	(C)	Ga.		Each
6	4	6	5 7/8"	3 7/8"	5 7/8"	24	1889K361	000000
8	6	8	7 7/8"	5 7/8"	7 7/8"	24	1889K363	000000
10	8	10	9 7/8"	7 7/8"	9 7/8"	24	1889K365	000000
12	10	12	11 7/8"	9 7/8"	11 7/8"	24	1889K367	000000

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.

Straight Reducers

Transition between duct of different diameters. Reducers also join larger duct with smaller duct that connects to equipment.

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

Duct Size		ID			Galvanized Steel		Corrosion-Resistant 304 Stainless Steel
(A)	(B)	(A)	(B)	Ga.		Each		Each



	4	3	3 7/8"	3 1/16"	22	1761K372	000000	2538K507	0000000


	5	4	4 7/8"	3 7/8"	22	1761K203	00000	2538K706	000000
	6	4	5 7/8"	3 7/8"	22	1761K72	00000	2538K241	000000
	6	5	5 7/8"	4 7/8"	22	1761K73	00000	2538K242	000000
	8	6	7 7/8"	5 7/8"	22	1761K206	00000	2538K709	000000
	10	6	9 7/8"	5 7/8"	22	1761K207	00000	2538K71	000000
	10	8	9 7/8"	7 7/8"	22	1761K208	00000	2538K711	000000
	12	8	12"	7 7/8"	22	1761K209	000000	2538K712	000000
	12	10	12"	9 7/8"	22	1761K211	000000	2538K713	000000
	14	12	13 15/16"	12"	22	1761K212	000000	2538K714	000000
	16	14	16"	14"	20	1761K213	000000	2538K715	000000


	18	16	17 15/16"	16"	20	1761K374	000000	2538K522	000000
	20	18	19 15/16"	17 15/16"	20	1761K375	000000	2538K523	000000
	22	20	22"	19 15/16"	20	1761K376	000000	———	0
	24	22	23 15/16"	22"	20	1761K377	000000	———	0

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.

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

Duct Hose Connectors

Slide these connectors into the ends of duct hose and secure with a clamp.

Straight Reducers

Connect two different diameters of hose.

Galvanized Steel—The strength of steel with added rust resistance. The thick coating stands up to wet and outdoor environments, but corrodes and pits if exposed to salt water or chemicals.

	For ID
	A	B	Lg.	Temp. Range, ° F	Material Thk.	Fitting Connection		Each
Galvanized Steel



		4"	3"	5 3/4"	-100 to 550	0.016"	Push On	5518K97	000000


		6"	4"	5 3/4"	-100 to 550	0.016"	Push On	5518K98	00000
		8"	6"	5 3/4"	-100 to 550	0.016"	Push On	5518K99	00000
		10"	8"	5 3/4"	-100 to 550	0.016"	Push On	5518K33	00000
		12"	8"	5 3/4"	-100 to 550	0.016"	Push On	5518K34	00000
		12"	10"	5 3/4"	-100 to 550	0.016"	Push On	5518K35	00000

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.

Straight Reducers

Transition between duct of different diameters. Reducers also join larger duct with smaller duct that connects to equipment.

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

Duct Size		OD		Galvanized Steel with EPDM Gasket
(A)	(B)	(A)	(B)	Ga.		Each
6	4	5 7/8"	3 7/8"	20	2226K19	000000
8	6	7 7/8"	5 7/8"	20	2226K21	00000
10	6	9 7/8"	5 7/8"	20	2226K22	00000
10	8	9 7/8"	7 7/8"	20	2226K23	00000
12	8	11 7/8"	7 7/8"	20	2226K24	00000
12	10	11 7/8"	9 7/8"	20	2226K25	00000

Noise Reducers

Turn down the rattle and hum of high-velocity airflow and vibration from fans and blowers. These reducers are insulated to decrease noise levels in your facility by half. They have gaskets on the ends for tight connections in spiral duct systems.

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

		Overall				Galvanized Steel with Rubber Gasket
Duct Size	OD	Dia.	Lg.	Sound Absorbed	Ga.		Each
4	3 7/8"	8 1/4"	23 5/8"	50%	24	2775K1	0000000
5	4 7/8"	9 1/4"	23 5/8"	50%	24	2775K2	000000
6	5 7/8"	10 5/8"	23 5/8"	50%	24	2775K3	000000
8	7 7/8"	12 3/4"	23 5/8"	50%	24	2775K4	000000
10	9 7/8"	14 3/8"	35 3/8"	50%	24	2775K5	000000
12	12 3/8"	16 3/4"	35 3/8"	50%	24	2775K6	000000

Noise Reducers for Quick-Disconnect Duct


	Duct Clamps

Muffle noise from high-velocity airflow and fans, blowers, and dust collectors. These reducers are insulated to cut sound levels in your facility by 25%. Install in quick-disconnect duct systems using clamps.

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

Duct Noise Reducers								Galvanized Steel Clamps
		Overall				Galvanized Steel
Duct Size	ID	Dia.	Lg.	Sound Absorbed	Ga.		Each		Each
3	3 1/16"	13 5/8"	28"	25%	20	1761K108	0000000	1761K103	000000
4	3 7/8"	15 1/8"	28"	25%	20	1761K109	000000	1761K22	00000
5	4 7/8"	16 1/8"	28"	25%	20	1761K111	000000	1761K23	00000
6	5 7/8"	17 1/8"	30"	25%	20	1761K112	000000	1761K24	00000
7	6 7/8"	18 1/8"	30"	25%	20	1761K113	00000000	1761K603	00000
8	7 7/8"	19 1/8"	35"	25%	20	1761K114	00000000	1761K137	00000
9	8 7/8"	20 1/8"	40"	25%	20	1761K115	00000000	1761K604	00000
10	9 7/8"	21 1/8"	48"	25%	20	1761K116	00000000	1761K138	00000
12	12"	23 1/8"	54"	25%	20	1761K261	00000000	1761K139	00000
14	13 15/16"	25 1/8"	58"	25%	20	1761K262	00000000	1761K145	00000
16	15 15/16"	27 1/8"	64"	25%	20	1761K263	00000000	1761K146	00000
18	17 15/16"	30 1/8"	64"	25%	20	1761K264	00000000	1761K101	00000
20	19 15/16"	32 1/8"	64"	25%	20	1761K265	00000000	1761K102	00000
22	22"	34 1/8"	64"	25%	20	1761K368	00000000	1761K333	00000
24	23 15/16"	36 1/8"	64"	25%	20	1761K369	00000000	1761K334	00000