Gauges

STEEL ROUND DUCT GAUGE - POSITIVE PRESSURE

+2” w.g.

Max
Dia.

Spiral
Seam Gauge

Fitting
Gauge

+4” w.g.

Max
Dia.

Spiral
Seam Gauge

Fitting
Gauge

+10” w.g.

Max
Dia.

Spiral
Seam Gauge

Fitting
Gauge

3" - 14"

28

26

15" - 26"

26

24

27" - 36"

24

22

37" - 50"

22

20

51" - 60"

20

18

61" - 80"

18

16

3" - 12"

26

26

13" - 16"

26

24

18" - 26"

24

22

27" - 36"

22

20

37" - 50"

20

20

51" - 60"

18

18

61" - 80"

18

16

3" - 10"

28

26

11" - 14"

26

24

15" - 26"

24

22

27" - 36"

22

20

37" -50"

20

20

51" - 60"

18

18

61" - 80"

18

16

STEEL ROUND DUCT GAUGE - NEGATIVE PRESSURE

-2” w.g.

Max
Dia.

Spiral
Seam Gauge

Fitting
Gauge

-4” w.g.

Max
Dia.

Spiral
Seam Gauge

Fitting
Gauge

-10” w.g.

Max
Dia.

Spiral
Seam Gauge

Fitting
Gauge

3" - 13"

28

26

14" - 15"

28

24

16" - 17"

26

24

18" - 20"

24

22

21" - 23"

24

20

24" - 26"

22

20

27" - 30"

22

18

31" - 34"

20

18

35" - 42"

20

16

43" - 48"

20

18

49" - 60"

18

18

61" - 72"

16

3" - 10"

26

26

11" - 13"

26

24

14" - 16"

24

22

17" - 19"

24

20

20" - 24"

22

18

25" - 26"

20

18

27" - 33"

20

16

34" - 36"

20

20

37" - 48"

18

18

49" - 60"

18F6

16

61" - 72"

18B4

3" - 8"

26

26

9"

26

24

10" - 11"

26

22

12"

24

22

13" - 14"

24

20

15"

22

20

16" - 21"

22

18

22" - 24"

20

16

25" - 26"

20

18

27" - 29"

18

16

30" - 36"

18

16

37" - 42"

18F12

43" - 60"

18F6

61" - 72"

16F4

An alphabet letter in the table means that reinforcement angles or their equivalent must be used at the foot intervals following the letter. The angle sizes are:

A = 1" x 1 1/8"	C = 1 1/2" x 1 1/2" x 3/16"	E = 2" x 2" x 3/16"
B = 1 1/4" x 1 1/4" x 3/16"	D = 1 1/2" x 1 1/2" x 1/4"	F = 2" x 2" x 1/4"

ALUMINUM ROUND DUCT GAUGE SCHEDULE

Duct Diameter

Maximum 2” w.g.

Static Positive

Spiral
Seam Gauge

Fitting
Gauge

Maximum 2” w.g.

Static Negative

Spiral
Seam Gauge

Fitting
Gauge

3" - 8"

9" - 14"

15’- 26”

27”- 36’

37”- 50’

51”- 60”

.025"	.032"
.025"	032"
.032"	.040"
.040"	.050"
.050"	.063"
.063"	.063"

.025"	.040"
032"	.040"
.040"	.050"
.050"	.063"
.063"	.063"
N.A.	N.A.

Refer to THE BHV INDUSTRIAL DUCT AND FITTINGS GUIDE or SMACNA ROUND INDUSTRIAL DUCT CONSTRUCTION STANDARDS FOR GAUGE SELECTION for other applications such as process exhaust.