Difference Between Horizontal and Vertical Mount Fire Dampers

Duct Work

• The ducts attached to a vertically-mounted fire damper run horizontally, whereas horizontally-mounted fire dampers connect ducts that run vertically. The purpose of duct work is to provide heated or cool air throughout the home. Fire dampers prevent any sort of fire from entering or exiting the duct system. Duct work connects to both sides of the fire damper's steel sleeve. This allows the fire damper to break off from the duct work in case the duct work falls during a fire.

Locations

• The placement of horizontally- or vertically-mounted fire dampers goes hand-in-hand with the location of their fire separation openings. A horizontally-mounted fire damper is installed in fire separation openings on the floor. Vertically-mounted fire dampers are typically placed on fire separation openings on partitions and walls.

Static-Rated Vs. Dynamic-Rated

• Static-rated fire dampers are usually part of vertically-mounted fire dampers. This type of fire damper relies on gravity to drop the damper's blades when a fire occurs. Static-rated fire dampers are usually part of HVAC systems that automatically shut down when fires occur. Horizontally-mounted fire dampers are almost always dynamic-rated units. A dynamic-rated fire damper utilizes springs to shut the damper's blades.

Locking Ramps

• Horizontally-mounted fire dampers have locking ramps to close the unit's blades. The locking ramps must be located on the topside of the unit in order for the blades to open and close efficiently. The locking ramps are typically made of steel. Vertically-mounted fire dampers do not have locking ramps since they rely on gravity to close the blades for them.

Sizes

• According to Nailor Industries, the minimum and maximum sizes of vertically- and horizontally-mounted fire dampers differ. Vertically-mounted fire dampers must be at least 4 inches wide and 3 inches long while a horizontally-mounted fire damper must be 4 inches wide by 4 inches long. Vertically- or horizontally-mounted fire dampers cannot exceed 5 feet wide by 4-1/2 feet long. The standard sizes for fire dampers are set forth by Underwriters Laboratories (UL), a U.S. product safety certification organization.