When it comes to building safety, understanding the various components that contribute to fire prevention and mitigation is crucial. Among them, fire dampers play a pivotal role. Designed to inhibit the spread of fire through ductwork, fire dampers are integral to the safety infrastructure of any building. They can give occupants time to safely evacuate and first responders time to do their jobs.
Selecting the right fire damper for the application is key to ensuring a building can perform as designed should disaster strike.
Over the years, building codes have evolved based on lessons learned from fires and unfortunate disasters that have occurred. Making sure that occupants have a fire-reinforced path through which to evacuate is one of those lessons. When designing a building, certain wall and ceiling assemblies may require fire ratings to ensure a safe path for egress. Fire ratings designate hours which represent how long the assembly can resist a fire before failing.
A fire damper is essentially a safety device installed in heating, ventilation, and air conditioning ductwork at the point where the ductwork penetrates fire-rated boundaries.
Without a fire damper, these penetrations through the fire-rated wall or ceiling would create a vulnerability that could allow a fire to spread. In the event of a fire, the dampers automatically close, usually triggered by a thermal element called a fusible link, to contain the fire and limit its spread. This mechanism is critical for maintaining compartmentalization in buildings, a key strategy in fire safety.
Not all fire dampers are created equal. Dampers come in many different varieties to suit the many different possible applications.
Two major types of blades are seen in fire dampers: curtain blade and airfoil 3V or AF multi-blade blade designs. Curtain blade dampers are often thought of as the standard design and are typically cheaper to manufacture. The blades fall like a curtain when triggered.
Multi-blade dampers sit in the air stream and rotate via a linkage to close off the flow of air. The blades can even be designed in low-leakage configurations to create a very tight seal even with high static pressure.
Simply put, fire dampers are triggered by fire, smoke dampers are triggered by smoke, and combination dampers are triggered by either fire or smoke. All three types of dampers respond in a similar fashion by releasing a blade stack or rotating blades to stop the flow of air. Code requirements typically dictate when a fire, smoke, or combination damper is required. In all three types, regular inspection of the damper is critical to ensuring the damper is ready to respond if needed.
Dampers can be either static or dynamic. Static fire dampers are typically gravity-assisted and designed for placement in HVAC systems where the fans turn off in the event of fire or smoke.
Some air handling systems are designed to operate during a fire to pressurize certain compartments. In these systems, dynamic fire dampers are needed. These dampers often have springs or other mechanisms to force the damper close in case of a fire. In addition to static or dynamic, fire dampers also come in Type A, Type B, and Type C varieties.
Type A fire dampers have blades that sit in the air stream. These types of dampers have higher pressure drops but are easy to install and less expensive to manufacture. They are typically used in applications where the blade stack intrusion in the air stream is not a big concern and the pressures will be fairly low (typically less than 3” w.c.).
Type B fire dampers provide a lower pressure drop by removing the blade stack from the air stream. With the blade stack out of the air stream, the air can pass through easily. Shorter height ducts (typically less than 12”) or high velocity ducts benefit greatly from Type B fire dampers. Shorter ducts suffer from a higher percentage of free area blocked by the blade stack in a Type A fire damper. Type B fire dampers solve the problem by removing them from the air stream.
Type C (Square/Rectangular) and CR (Round) fire dampers are the highest performing type of fire damper. They typically have a collar for easy duct installation and are designed for medium to high velocity ductwork. Like Type B fire dampers, Type C fire dampers fully remove the blade stack from the duct area to maximize free area. Type C or CR fire dampers can be designed for high pressure applications (often up to 10” w.c.) and can be configured with transition collars to allow for round or oval ductwork to connect properly.
When comparing Types A, B, and C/CR, it's essential to consider the specific environments and requirements of the HVAC systems they are intended for. The cost typically goes up as you go down the alphabet with Type A being the cheapest and Type C being the most expensive. Type C fire dampers can be used in any application. Type B fire dampers can be used in place of Type A fire dampers. Type A fire dampers can only be used when intrusion of the blade stack into the air stream is not a concern.
When evaluating which type of damper is needed for a certain location or application, it is important to choose the lowest-rating fire damper that meets the application requirements. Over-specifying requirements by, for example, using only Type C dampers even when Type B or Type A would be sufficient leads to excessive costs and over-engineering. The choice between Fire Damper Type A, B, or C largely depends on the specific needs of the building and the HVAC system in place, and requires thoughtful consideration.
Choosing United Enertech for your fire damper needs means opting for quality, compliance, and customization. Their products are known for their robust construction and adherence to stringent safety standards. The ability to customize dampers to specific requirements sets United Enertech apart by ensuring that every building gets the most effective and efficient fire protection solution.
To learn more about fire dampers and the difference between Type A, Type B, and Type C, reach out to the fire damper experts at United Enertech today!
