Orfice Plates

[celwing]

I am working on a project that requires spiral duct perforated diffusers. The length of the diffusers require multiple orfice plates to control airflow to an even distribution throughout the length of the perforated spiral diffuser. The perforated open area is 23 percent. Looking for a formula to calculate the sizes of the multiple orfice plates.

Go to McNichols Perforated Metals (Do a Goggle search.) In their catalog they tell you the free opening area of their different sheets. We build these diffusers all the time. I pity you on this project. We have done this before and reinforcing that pipe is a royal pain in the ass. If I can be any more help drop me a line, Bob