Smoke vents are not easy to close! Unlike a roof hatch, the smoke vent natural position is open. The spring forces want to open the doors and need enough opening force by code to lift 10 lb/sq ft. On a typical 4ft by 8ft configuration, the closing force is 320 lbs, or about 160 lbs per door on a double leaf unit. You need the same 160 lbs of force to close the door.
Options for closing the door include:
- Manual – from the rooftop. This may take a couple of strong people to put their weight on the unit until it latches.
- Winch – This option is frequently used in theatre applications where they are rigged down to the stage floor so you can crank the winch to close the doors.
- Motorized Control – These include open/close push button controls and electrical relay ties into the fire alarm.
Code also requires that a dampener be in place to slow the opening of the doors – without the dampener, the doors would open fast with a deadly force.
Nystrom understands the complexities with Smoke Vents, codes and applications. For more information please visit www.Nystrom.com.