Deduct the frame area from opening area for vent area by NFPA 68?

[designsimple]

When calculating the actual vent area, should the frame area of vents be deducted from opening area? Thanks,

 

[bimr]

Yes. The manufacturer will quote the actual vent size. The actual vent size is not something that you calculate.

The actual vent size will be about 7-10% smaller than the vent frame opening size. The frame opening size is also smaller than the vent frame outside dimensions.

 

[bimr]

Forgot the link to the suppliers:

http://www.contdisc.com/IM_Uploads/DocLib_182_CDC CFR-CFS vent panels.pdf

http://www.cando2001.com/disk/77-8015/77-8015.htm

 

[designsimple]

Thanks a lot for information.