Sqaur diffuser plenum sizing

[123131415]

Dear member,

I am working with project wherein square diffuser is supplied by other vendor/manufacture and plenum box above diffuser is supplied by duct manufacture. Plenum box is suppled though the thermally flexible duct which served by CAV/VAV.

Diffuser schedule

Neck size flow

150 x 150 50L/S

225 X 225 51-100 L/S

300 X 300 101-190 L/S

375 X 375 191-300 L/S

My problem is

1). How to size the plenum box for each diffuser.

2) spigot size i.e inlet size to the plenum box for flexible duct connection.

Thank you.

 

[dtimberlake]

My recollection tis the ASHRAE handbooks have practical information about plenum sizing and much much more.