The EPA has come to our facility and has required us to raise 60 of our exhaust stacks to a given height.
I am wondering with initial data how i can get final CFM.
So for example. We have a stack with a current height of 41.92'. Height required is 66.58' which is an increase of 24.66'. The stack system has been designed such that there is 36' of stack height that starts at a furnace exit (which is decoupled) and goes up to rooftop height and ties inline with an exhaust fan which in turn has additional stack height inline above it. We'll be replacing the 5.92' of stack above the fan with a 30.58' stack which will get us to our goal of 66.58'. I don't want to overdraft nor under draft the furnace with the stack height modification.
Again all that is changing is stack height.
Inner duct diameter is the same at 1.33FT. Temperature is 112 F. Initial SCFM is 2684 before modification. I believe the static pressure for the specific duct is .4inwc per 100ft.
Fan details: design CFM - 3570. Design Static Pressure - 2.5inwc. Fan RPM 1518 and designed max RPM is 2026.
I need help finding a formula or something to get final CFM.