Engine Room Air Dampers (Fire Flaps) Explained

August 9, 2023

Brad Marsden

Director - Marine Air Flow International

35 Years Experience in the Marine Industry

View Brad's Info

Engine Room Air Dampers And Why Your Boat Needs Them

Air Dampers (Fire Flaps) mounted to our AC High Volume Fans

A fire damper on a boat or ship is a crucial safety component, primarily designed to prevent the spread of fire and smoke through a vessel's ventilation system.  While the term "fire flap" is outdated and we now call them Air Dampers, however you refer to them - they are a necessary component in your engine room ventilation system.


Here’s a comprehensive understanding of fire dampers in a maritime context.


What is an Air Damper?

An Air Damper is a device installed as part of a vessel's ventilation system. In its simplest form, it consists of a set of louvers or blades that can close tightly, thereby sealing off the duct and/or air supply.


These blades are held open under normal conditions but are designed to either be manually closed or automatically closed when a certain temperature (indicative of a fire) is reached. They can also be set up to be activated upon receiving a signal from a fire detection system.


Why are Fire Dampers Required on Boats?

  1. Safety Regulations: Maritime safety regulations worldwide often mandate the use of air dampers in specific areas on ships. These regulations ensure that ships meet a global level of safety and are often essential equipment that must be installed for your vessel to meet survey standards.
  2. Prevent Spread of Fire: The main purpose of a fire damper is to stop or slow down the spread of fire and smoke through the vessel's ventilation system. Since ships have closed environments, unchecked fire and smoke can quickly become fatal to those on board. By triggering the Air Damper a fire is starved of Oxygen making it more managable for crew or fire fighting systems to extinguish.
  3. Protecting Equipment and Cargo: By restricting the spread of fire, fire dampers can help protect both the ship's vital equipment and any cargo on board from damage.


Benefits of Air Dampers (Fire Flaps) on Boats

  1. Lifesaving Measures: In the event of a fire, fire dampers can buy critical time for the crew and passengers, allowing them to evacuate or fight the fire.
  2. Maintain Structural Integrity: By stopping the spread of fire, dampers can help maintain the structural integrity of the ship, preventing further damage and potential loss.
  3. Lower Repair Costs: By containing fire damage to a smaller area, the repair costs post-incident can be significantly reduced.
  4. Insurance Premiums: Having a proper fire prevention and containment system, including air dampers, may reduce insurance premiums for ship owners.


Different Types of Air Dampers

There are various types of fire dampers, including curtain, multi-blade, and combination fire/smoke dampers. The type used often depends on the specific requirements of the ship and its ventilation system.


Some recreational vessels can make use of Aluminium Air Dampers, however most global survey codes require the fire dampers to be stainless steel.


How Air Dampers are Triggered


Our Air Dampers come with an optional control cable that extends from the damper to a point outside the engine room. This manual system is simply activated by releasing the pull ring from its holding bracket. Doing so activates the spring-powered damper blade, cutting off the air supply to the engine room. Additionally, this control has a semi-automatic feature. Should a fire or extreme heat be near the control cable, which is made of synthetic material, it will melt, causing the flap to close automatically.The cable melts at 140 degrees Celsius.


We can also supply an automatic system to trigger the fire flaps. This actuator works via a temperature probe mounted in the air stream inside your engine room. When the probe sense temperatures of 72°C it will shut the damper automatically. The actuator will also trip if the power supply to the system is turned off. These automatic controllers are a great option for a set and forget situation especially where your vessel might have a rotating crew.


Maintaining your Air Dampers

Like all safety equipment, fire dampers must be regularly inspected and maintained to ensure they function properly when needed. This often involves checking the damper's triggering mechanism, its ability to close fully, and ensuring that it isn’t obstructed by debris. We recommend scheduling an annual inspection for all your fire equipment including any installed dampers and triggering systems.


Instructing Crew On The Use of Air Dampers


Modern ships often integrate fire dampers with their broader fire detection and prevention systems, allowing for automated responses to potential fire threats. Even though this might be the case, you do need to instruct your crew on how and when to reset the dampers and the trigger. 


We recommend creating a plaque or poster that is part of your proceedures instructing crew on actions to take during a potential or actual fire. Some points to include on this plaque might be:

  • sound the alarm and check no one is the engine room
  • ensure air dampers have been triggered and are closed
  • position vessel safely and shut down engines.
  • turn off fuel supply with remote valves.
  • turn off ventilation fans with E stops.
  • activate fire suppression system 
  • f in doubt wait for emergency crews.


Most of all, ensure your crew understands not to open the engine room until ALL heat sources have been eliminated.


Understanding the Use Of Air Dampers

In conclusion, fire dampers on boats and ships are an essential part of maritime safety, offering protection to the vessel, its crew, passengers, and cargo. Like all safety measures, their value is often unseen until they're critically needed – and in such moments, they can mean the difference between disaster and recovery.


Get in touch for any help with Air Dampers for your vessel. We would be happy to help. More info and Spec Data sheets can be found on our Air Dampers page.


Marine Air Flow air intake grilles, dampers and fans on a Port Authority fire boat
By Brad Marsden July 30, 2025
Marine Air Flow air intake grilles, dampers and fans on a Port Authority fire boat built by Birdon Marine.
By Brad Marsden June 10, 2025
Optimising Engine Room Ventilation for Abu Dhabi’s High-Speed Ro-Pax Ferries As part of Abu Dhabi’s ongoing investment in advanced maritime infrastructure, the AD Ports Group commissioned two high-speed Ro-Ro ferries to operate between the UAE mainland and Delma Island. Carrying 250 passengers and 25 cars per trip at a service speed of over 30 Knots is pretty impressive , and you'd have to agree they are certainly very tidy looking Roll On Roll Off Ferries!! Designed for both passenger comfort and operational performance, these cutting-edge vessels required a ventilation solution that could meet the rigorous demands of the Gulf’s climate and the intense operating conditions of four powerful MTU engines per vessel. Our team was proud to be selected to design and deliver the engine room ventilation system for these state-of-the-art ferries, ensuring they remain safe, efficient, and reliable at sea. Engineering the Future of Fast Ferry Travel Built to carry up to 194 passengers and 25 vehicles, each of the 56-metre-long catamarans has been equipped with four MTU 16V4000M65L high-performance engines driving Kongsberg KaMeWa waterjets. This powerful propulsion setup enables cruising speeds of up to 35 knots, making the ferries among the fastest in their class within the region. Inside, the vessels feature modern amenities such as a VIP lounge, children’s play area, two cafes, five toilets, and full wheelchair accessibility, highlighting AD Ports Group’s commitment to both efficiency and passenger experience. Operating in the heat of the Persian Gulf, however, presents unique engineering challenges. The heart of this lies within the engine room where temperatures, airflow, and safety systems must be tightly controlled to prevent overheating, ensure compliance, and protect both crew and machinery. A Tailored Ventilation Solution for Demanding Conditions The brief for this project was clear: create a ventilation system that could not only manage the extreme thermal loads generated by four high-output marine engines but also comply with international marine safety standards, including fire isolation and redundancy protocols. Key features of the system we delivered include: Marine-Grade Ventilation Dampers : Built from corrosion-resistant stainless steel, our dampers are designed for longevity and reliability in a saltwater environment. Integrated Auto Close Capability : The dampers are configured to close rapidly in the event of a fire, helping to isolate the engine room and restrict oxygen supply. High Airflow Capacity : Designed specifically for the compact, high-output layout of the engine rooms, the system allows for maximum airflow and heat dissipation under full load. Moisture and Salt Mist Defence: Our Intake grilles are known globally for their excellent capability of reducing salt mist and spray into your engine room. Here they allow a vessel operating in already extreme conditions to require far less ongoing equipment replacement. Redundancy & Safety : With automated control options and manual overrides, the system ensures continuous operation and safety during engine shutdowns or emergencies. Delivering Results at Sea With the ventilation system now fully installed and operational, the Ro-Pax ferries have successfully completed sea trials and are ready to begin service. The performance of the engine room ventilation under load has exceeded expectations, maintaining optimal operating temperatures even during high-speed runs in the peak Gulf heat. In addition to thermal performance, the system’s fire isolation capability offers an added layer of safety, helping these ferries meet stringent international compliance standards while delivering peace of mind for operators and passengers alike. Reflecting on the Project This project underscores the critical importance of high-performance ventilation systems in modern vessel design. From the intense thermal loads of multi-engine configurations to the need for rapid fire response and corrosion resistance, every detail matters when it comes to marine safety and reliability. We’re proud to have played a key role in supporting this milestone for AD Ports Group and Abu Dhabi’s maritime future and we look forward to bringing this level of engineering excellence to future vessel builds across the region and beyond. Talk to Us About Your Marine Ventilation Needs Whether you’re designing a new-build high-speed ferry or retrofitting an existing vessel, we offer tailored ventilation solutions that combine safety, efficiency, and performance. Get in touch with our team today to learn how we can support your next marine engineering project.
Marine Air Flow has achieved JOSCAR certification, used by Military and Government organisations
By Brad Marsden June 5, 2025
Marine Air Flow has achieved JOSCAR certification, used by Military and Government organisations in Australia
Brad, Blake and Kal accepting an award.
By Brad Marsden June 4, 2025
Marine Air Flow is 20! Its been a huge 20 years and we have lots of people to thank. Check out how we got here.
A vessel in rough seas with multiple crew on deck.
By Brad Marsden February 19, 2025
Learn how Delta T optimizes engine room cooling on boats, ensuring performance, safety, and efficiency. Discover tips and trends for effective management.
Black Watch 40 with Marine Air Flow Teardrop Intake Grilles
By Brad Marsden January 30, 2025
Do you have a Black Watch 40 that has trouble with salt mist and over heating? You can retrofit an engine room ventilation system to solve that!
Marine Air Flow winning the 2024 Small Business Export Award
By Jenny Marsden November 23, 2024
We are very excited to announce that Marine Air Flow has won the 2024 Export Award for Small Business.
By Brad Marsden July 30, 2024
We are proud to announce we are the June 2024 winners of the Gold Coast Business Excellence Award.
The Woolgoolga RIB - another Marine Air Flow engine room ventilation project.
By Brad Marsden June 4, 2024
A new rescue vessel built by The Whiskey Group for the Australian Volunteer Marine Rescue team in New South Wales.
Svitzer Pilot transfer boat built by Dongara Marine with MAFI's engine room ventilation equipment.
By Brad Marsden May 29, 2024
Another completed project for Dongara Marine. This time a pilot transfer boat for Svitzer Marlin that will operate from Woodside Oil and Gas in the Pilbara.