Elevator pressurization and stairwell pressurization fan sizing code/guidelines

Our company has been working on several jobs that require elevator and stairwell pressurization fans. One of the jobs an engineer used CONtam to model how in the event of a fire the building would behave. Contam is only as good as the inputs you give it but it also considers wind pressure, stack effect, elevated fire floor temperatures, among other things.

What we have found is there is a prescriptive option in the code for elevator pressurization at 1000 CFM per door.

On stairs ask for adjustable door sweeps the balancer can adjust the leakage area in order to maintain a pressurized shaft in between the code static pressure values.

Fan VFD's are only for balancing and not UL listed UUKL for control (similar to fire alarm) so it cannot be used to modulate based on a pressure transducer.

First floor you need a method for relief because the elevator doors open on this floor (recall floor) letting a bunch of air out of the shaft.

Not using CONtam we have used.

850-1,500 CFM/door for elevator systems

and

750-1,000 CFM/door

I would like to get other PE's thoughts on this that have designed these systems before.

There has also been talk in our office of needing E-power AND a seismically certified fan for sub-duct systems. In order to make sure that no smoke goes into another dwelling if the fan fails. In the event of an earthquake the fan already needs e-power by code but does not state it needs to be seismically certified. Using sub-duct risers replace the need for FSD's and our (the 3 engineers here) are in agreement then that would mean the sub-duct fan would need to be seismically certified....phew, a lot of thinking on a Friday.

bump.....?

It's been a while since I've designed one, but I'll take a look and see what I can find.

Well, I looked through all my old stuff, but couldn't find anything on it.  I guess it's not surprising since the last time I designed a high rise was over 10 years ago.  Sorry man.

MetsFan said:

Well, I looked through all my old stuff, but couldn't find anything on it.  I guess it's not surprising since the last time I designed a high rise was over 10 years ago.  Sorry man.

Click to expand...

No worries at all man! I appreciate you looking, thanks :0 

I've done something recently. In our office we do (50 fpm) x (door area) and it works out close to what a fire protection study would generate. I'll look for that study to confirm. We would have the fan tied to the fire alarm system and it would only activate upon alarm activation. Otherwise, it is off. We only use it to keep the smoke out of the exit stairwell.

johnnyl507 said:

I've done something recently. In our office we do (50 fpm) x (door area) and it works out close to what a fire protection study would generate. I'll look for that study to confirm. We would have the fan tied to the fire alarm system and it would only activate upon alarm activation. Otherwise, it is off. We only use it to keep the smoke out of the exit stairwell.

Click to expand...

Yeah that sounds about right to get to 1,000 CFM. 3'x6.75' ish at 50 cfm is 1012.5 CFM.