Carrier CDII-184R1-0CTR4 Installation & Operation Manual page 18

b.
8. Total pressure loss calculated must be less than fan static. If not, select a different initial velocity
and repeat from step 2.
Maximum
S.NO.
side
1. UPTO 30"
2. 32" to 40"
3. 41" to 60"
4. 61" to 90"
91" and
5.
above
NOTE: IF SHEET METAL USED IS ALUMINIUM, USE ONE GAUGE HIGHER.
9. Now, for each circuit part or air outlet, find out equivalent round duct area and rectangular duct
dimensions using Friction Chart and the relation given in step 4. Use a constant value of friction
rate (from step 3), and air quantity through the duct length (= original CFM - CFM delivered
through the outlet) to enter in Friction Chart to find duct dimensions.
II. Fabrication and installation of ducting
Refer Table 1 (next page) for ducting specifications for ducts of different sizes. Follow recommended
ducting principles. All the angles iron flanges should be welded electrically, and holes drilled.
All the angle iron flanges should be connected to the GSS duct by rivets at 4" centers. All the flanged
joints should have ¼" thick felt / foam gasket or sealed with silicon sealant. Felt should be stuck with
varnish and the hole in packing should be burnt through.
The GSS duct should be lapped ¼" across the flange.
TABLE 1: DUCTING SPECIFICATIONS
Thickness (G)
(for GSS duct)
24
Flanges with 1/4" GI bolts &
22
Nuts at 5" center or slip joint
22 Flanges with 5/16" GI bolts &
20 Flanges with 3/8" GI bolts &
18 Flanges with 3/8" GI bolts &
Type of connection
24BG GSS flanges /
1 1/4"x3/16" angle iron
1 1/4"x3/16" angle iron
Nuts at 5" centers.
1 1/2"x3/16" angle iron
Nuts at 5" centers.
2"x1/4" angle iron
Nuts at 5" centers.
18
Bracing
Cross bracing
Cross bracing
Diagonally with 1 ½"x1/8"
angle iron if the piece is more
than 4' long.
Diagonally with 1 ½"x1/8"
angle iron if the piece is more
than 4' long.