I have been asked about this many times and I don’t have a good answer. I’ve got my fingers crossed that someone reading this can help. The issue is when you have a pressurized stairwell that is required for some buildings for smoke control. With the increased pressure in the stairwell, doors swinging into the stair become more difficult to open, and doors swinging out of the stair may not close and latch.
For the outswinging doors that don’t close, the first thought is often to increase the closing force of the closer, but this increases the opening force as well. For many jurisdictions, the maximum opening force for a fire door or exterior door is 15 pounds to release the latch, 30 pounds to set the door in motion, and 15 pounds to open the door fully (your jurisdiction’s requirements may vary). What if that’s not enough force to get the door closed?
The next thought may be to add an automatic operator to assist with opening the door now that the opening force is so high. There are two problems there – 1) low-energy automatic operators are limited by code to 15 pounds of opening force (that’s why they don’t need safety mats and guide rails) and 2) automatic operators on fire doors are required to be deactivated on fire alarm. If you only have 15 pounds of opening force fighting an excessive amount of closing force, this doesn’t seem like it would help. Going to a full powered operator that is not subject to the 15-pound limit would require safety sensors and possibly guide rails. And during a fire alarm when the stair is pressurized, the auto operator is not functional if the door is fire rated.
When our specwriter apprentices are in Boston for training, I always take them on a field trip to a building where they can see some doors with this problem (and lots of other doors). In this university classroom building, there are two outswinging pairs leading from the stairs to a lobby. The doors have the closers that were originally specified and installed, added automatic operators with safety sensors both sides of the door, AND magnetic holders which hold the door open until the fire alarm is activated. I have no idea if they actually get the job done – what is the purpose of the auto operators if the doors are held open when there is no alarm, and the operators are deactivated when there is an alarm? If any of the apprentices reading this have some photos of these openings, send them along and I’ll post them.
Without knowing much about stairwell pressurization, it seems like there is too much pressure in the stairwell and it must be reduced. But releasing too much air will mean that the pressure in the stairwell is less than what is required by code. I didn’t do very well in physics and maybe that’s why I haven’t had a brainstorm on this. I saw a nifty product called the Closer Pressure Equalizer a few years ago, but I haven’t seen it on the market.