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.
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.
To Next Page
Loading...
