Consumption and Real Estate
Fire Damper Air Flow Direction?
Question : Fire Damper Air Flow Direction?
Whilst performing a fire safety inspection of an residential facility, I happened upon some ducts with the words “FIRE DAMPER” stenciled upon its surface. Upon opening a steel door on one of the aforementioned ducts a strong air current was observed. My question:
Are all fire dampers moving air from the building to the outside, during normal operation. And secondly, assuming that they are moving air from the inside of the building to the outside, is the air at any point recycled back into the building.
The ducts themselves were approximately 12″ by 8″, which connected to ducts approximately 4′ by 3′. Also it was a four story building in Texas.
residential inspection
Best answer:
Answer by donnie m
A fire damper is suppose to close in case of a fire, When temperture gets to what the damper is designed for it will close. To keep it from spreading thru out the building.
The firedamper is used to protect a fire rated partition or barrier, not the duct itself.
The direction of the airflow is determined by the HVAC system itself, not the firedamper. Generally, nowadays most curtain style firedampers are rated for bi-directional airflow. They have locking ramps which hold the blades in place when they’ve closed.
There should also be a label on the damper, which says “Rated for static systems” or “Rated for dynamic systems”. If it is rated for static systems, please make sure that the HVAC system is static. Meaning, the fans will shut down during a fire emergency. Dynamic systems are usually only used for smoke evacuation during a fire emergency, in which the fans remain on during a fire emergency. Dynamic firedampers are usually rated for closure against 2000-3000 FPM depending on size, and up to about 4″ water gage. Each firedamper manufacturer usually has multiple models and sizing restrictions, due to their test results on that model.
To sum it up:
1) Check if the damper is static or dynamic, make sure it coincides with the HVAC system. If you are using a dynamic damper in a static system, it’s ok. If you are using a static damper in a dynamic system, it’s not ok.
2) Airflow direction is dependant on the HVAC system, most systems will intake fresh air and exhaust processed air. Check the labels on the firedamper to see if they designate an airflow direction.
If you have more questions, please visit http://www.firedamper.com and contact us directly.