Smoke & Fire Dampers

Fire and smoke dampers are designed for one thing. To limit/stop the spread of the fire, or smoke from one side of the wall, to the other. They are required to be inspected, and tested the first year after installation, and then once every 4 years, with the exception of a hospital being every 6 years.

The walls they go in, are usually fire rated walls, smoke rated walls, or a combination of the two. They are installed inside of the penetration made for an HVAC duct.

There are different types of dampers.

Gravity assisted fire dampers are merely a simple door that is folded up, with a fixed temperature link that melts at a specific temperature. When the link melts, gravity pulls the door down to block the duct. Because the door is not very heavy in most cases, these are only used when the current of air is low, or in small rooms that do not have a large flow of air.

Spring assisted fire dampers activate the same as the gravity assisted dampers. They have a fusible metal link that melts at a specific temperature, and when it melts the spring pushes the door closed. Because of the spring, it can be mounted in all different directions, or even level with a floor. They come in different shapes, which include circular to accommodate circular hvac ducts, as well as the usual square/rectangle variety. Whenever a duct is too large to make a damper of sufficient fire rating a viable option, you can stack them, and put them next to each other to make the fire rating monetarily sensible.

There are also motorized dampers. Motorized dampers vary in size, and how they are actuated. They can be actuated by a smoke detector, a fire alarm, a loss of power, and a test switch. Test switches can be utilized when it is between the power supply, and the damper motor. This is the same as a loss of power, because of the way the motors are set up. Some motors have a constant pressure, or spring that push them in the direction of ‘closed’, that way when the power is cut, or the test switch is activated, they will move to the closed position. Smoke detectors, and the fire alarm can also trigger this power cut, or send a signal that activates the motor to push to the closed position. This can require either a manual reset of the damper, and/or a manual reset of the alarm system.

If you have any other questions, feel free to contact us, or you can view our damper section for the statutes that regulate the inspections, and maintenance required for them.