The Basics of A Combination Fire and Smoke Damper

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combination fire and smoke damper

Whether you’re designing the construction of a new commercial office building or planning a renovation, understanding the types of safety equipment, including dampers, that your building needs is critical to keeping its occupants safe.

Although we’ve already looked at the different types of dampers, this blog will take a closer look at one of the most versatile types of dampers: combination fire and smoke dampers.

What Is a Damper?

The first thing to understand is the design and purpose of a damper. A damper is a device that regulates or stops airflow inside air-handling equipment such as a chimney, ductwork, or air handler.

When it comes to heating, ventilation, and air conditioning (HVAC) dampers, you’ll find three different types:

  • Fire damper
  • Smoke damper
  • Combination fire and smoke damper

Why Are Dampers Important?

Think about the air conditioning or heating system of a large building. If you open the ceilings, you’ll likely see extensive ductwork running throughout the building. This ductwork carries hot or cold air from the HVAC unit to each room, keeping the temperature comfortable and protecting the air quality.

Although it’s convenient to have ductwork that runs through several rooms and floors of a building, without dampers, it can be hazardous in the event of a fire or other emergency because smoke and flames can travel through the ductwork very quickly, causing a situation to become very dangerous. Therefore, we rely on fire dampers, smoke dampers, and combination fire and smoke dampers to help mitigate the risks associated with the convenience of large heating and cooling systems.

What Is a Fire Damper?

A fire damper is a type of damper that is used to protect HVAC ducts and prevent the spread of fire in buildings. They are passive fire protection products that play an essential role in the safety of residents or employees, first responders, and the building itself.

For example, let’s say there is a large office building that has a kitchen in the middle. The temperature of each room in the building is controlled by one central thermostat and HVAC unit, and HVAC ductwork runs throughout the building to connect all the rooms and keep the temperature consistent. Then, one day, a fire starts in the kitchen.

If the fire can reach the vent that allows air to flow through the ductwork, and there is no damper, the fire can quickly spread throughout the ceiling of the entire building. Instead of blowing temperature-controlled air into each office, the ductwork acts as a highway for the fire to easily access every other room in the building. By the time someone can call for a fire truck, the fire has already spread, putting people and the entire building at risk.

How Does a Fire Damper Work? 

There are two main fire damper styles:

  1. Static fire dampers
  2. Dynamic fire dampers

Both types help protect against the spread of fire and smoke within HVAC ductwork but in different ways.

Static fire dampers cut off all airflow within the ductwork in the event of a fire. They are triggered by a fire detection system like a fire alarm or sprinkler system. They can also come with fusible links set to close automatically when exposed to certain temperatures.

Dynamic fire dampers are designed to work when the HVAC blower continues to run. They must be stronger and more durable than static fire dampers because they have to close against the flow of air.

It can be designed as a multi-blade or curtain. A curtain-style fire damper has accordion-type blinds of steel held at the top and released by either a spring or a combination of a spring and gravity. Multi-blade fire dampers have louver-style slats that can rotate, open, or close in unison. This style is more versatile because it allows the flow of air to be changed without closing the damper entirely.

What Are Smoke Dampers? 

Smoke dampers are similar to fire dampers in that they are installed within HVAC ductwork or other openings to prevent the spread of smoke in an emergency. These passive fire protection products are triggered by smoke detectors and can also be closed remotely or in connection with another fire protection system.

Check out this blog to learn five things you didn’t know about smoke dampers!

What Are Combination Fire and Smoke Dampers?

Combination fire and smoke dampers are the best of both worlds when it comes to passive fire protection products. This style helps protect against the spread of smoke and flames within an HVAC system and is available in three class ratings:

  • Leakage
  • Low leakage
  • Ultra-low leakage

The amount of leakage for combination fire and smoke dampers is measured in cubic feet per minute (CFM) and varies by class. According to the International Energy Conservation Code (IECC), dampers that are integral to the building envelope may have “a maximum leakage rate of 4 cfm per square foot (21 L/s per square meter) at 1.0-in. w.g. (0.25kPa) when tested under Air Movement and Control Association (AMCA) 500D.”

The amount of leakage depends on pressure, not airflow. Most dampers typically have seals around the frame where the blades meet, also known as the jamb, but the success in reducing leakage depends on the type of seal used.

Combination fire and smoke dampers must undergo endurance testing to be UL certified to determine how long the damper can protect against heat. Some tests include high-pressure fire hoses to test the combination fire and smoke dampers’ ability to withstand thermal and structural shock and cycling tests that measure the endurance of the combination fire and smoke dampers in opening and closing successfully.

What Kind Should I Get?

Unless you are an HVAC or ductwork professional, choosing the right fire, smoke, and combination fire and smoke dampers is best left to the experts. These dampers provide protection that can mean the difference between life and death, which should always be taken seriously.

Lloyd Industries is an expert in fire protection products, including combination fire and smoke dampers, access doors, fire doors, louvers, and more. With over 35 years in the industry, the team offers everything from blogs about fire dampers and how to keep your home cool in the summer to shop for the highest quality HVAC products available.

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