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Design Assistance:
Conditions of Sale
Technical Information
Installation Tips
Sizing Information
  Sizing Pipe Systems
  Sizing Branches

Worksheets
Glossary of Terms


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Design Assistance -
Sizing Suggestions

Sizing a Pipe System
DUCT INCORPORATED offers assistance for those who need help designing a piping system. We can help determine the correct pipe size and configuration that will supply the flow you need. Please contact us at 1 877-BUY-DUCT for assistance.

USING THE CFM/FPM CHART. The following chart allows you to pick
the correct pipe for the required CFM.

To prevent waste material from dropping out of the air stream, each type of material needs to be conveyed at different velocities. (See table on page 28.) For example, some waste materials flow well at 4500 feet per minute (FPM). Reviewing the chart, a 4” pipe will convey 395 CFM at 4500 FPM. This means that a 4” pick-up on a machine will use 395 CFM from the filtering system; or, if you know that a machine will require approximately 400 CFM to remove the waste, you should use a 4” pipe for that purpose.

Air Volume in Ducts in Cubic Feet per Minute (CFM)
2000
2500
3000
3500
4000
4500
5000
5500
6000
6500
7000
3
100
125
150
170
195
220
245
270
295
320
345
4
175
220
260
305
350
395
440
485
525
570
615
5
275
340
410
475
545
615
680
750
820
885
955
6
395
490
590
685
785
885
980
1080
1180
1275
1375
7
535
670
800
935
1070
1205
1335
1470
1605
1735
1870
8
700
875
1050
1220
1395
1570
1745
1920
2095
2270
2445
9
885
1105
1325
1545
1765
1990
2210
2430
2650
2870
3090
10
1090
1365
1635
1910
2180
2455
2725
3000
3270
3545
3820
12
1570
1965
2355
2750
3140
3535
3925
4320
4710
5105
5500
14
2140
2675
3205
3740
4275
4810
5345
5880
6415
6950
7485
16
2790
3490
4190
4885
5585
6285
6980
7680
8380
9075
9775
18
3535
4420
5300
6185
7070
7950
8835
9720
10600
11485
12370
20
4635
5455
6545
7635
8725
9815
10910
12000
13090
14180
15270
22
5280
6600
7920
9240
10560
11880
13200
14520
15840
17160
18480
24
6285
7855
9425
10995
12656
14135
15710
17280
18850
20420
21995
26
7370
9210
11055
12900
14740
16580
18420
20270
22110
23950
25800
28
8550
10685
12820
14960
17100
19230
21310
23500
25650
27780
29920
30
9800
12260
14700
17170
19625
22080
24530
26990
29440
31890
34350
32
11160
13950
16750
19541
22330
25120
279120
30700
33490
36380
39070

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Sizing Branches
Example: When working from your machines back toward the filter, you have a 5” drop that rises and joins with a 6” drop (see diagram below). How do you figure what size branch you’ll need?

The 5” pipe carries 615 CFM at 4500 FPM (see chart above). The 6” pipe needs 885 CFM at the same velocity of 4500 FPM. Added together, there is a total of (615 + 885) 1500 CFM coming together.

Referring back to the chart under the 4500 CFM column, 1500 CFM is not listed, but is close to the 1570 CFM listed for an 8” pipe. This states that the 5” joined with the 6” requires an 8” pipe to carry the combined material at the correct velocity. The branch will need to be 8” on the downstream end reducing down to a 5” with a 6” branching off of it. This would be listed as an 8-5-6 branch.

Ducting Branch Sizing 1

Example: When working from your machines back toward the filter, you have a 5” drop that rises and joins with a 6” drop (see diagram below). How do you figure what size branch you’ll need?

he 5” pipe carries 615 CFM at 4500 FPM (see chart above). The 6” pipe needs 885 CFM at the same velocity of 4500 FPM. Added together, there is a total of (615 + 885) 1500 CFM coming together.
Ducting Branch Sizing 2
Referring back to the chart under the 4500 CFM column, 1500 CFM is not listed, but is close to the 1570 CFM listed for an 8” pipe. This states that the 5” joined with the 6” requires an 8” pipe to carry the combined material at the correct velocity. The branch will need to be 8” on the downstream end reducing down to a 5” with a 6” branching off of it. This would be listed as an 8-5-6 branch.

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