Andy Scott, Managing Director of Poole, UK, based Marine Components International, has recently been given the global distribution rights for the A60 rated fire dampers produced by BSB Engineering. He says that while fire dampers are mandatory for ships above 500 gross tons, they are often overlooked on smaller vessels. A spate of superyacht fires recently has focussed on the benefits of this basic technology.
The term ‘fire damper’ is a bit misleading as it has nothing to do with water. Instead, it is best described as ‘a device installed in air transfer ducts and designed to close automatically on the detection of excessive heat.’ The metal construction and tightly fitting blades ensure that any fire, or smoke, is prevented from moving from one compartment to the next, and so buys more time for firefighting and evacuation.
The most basic types consist of a steel frame, either circular or rectangular, in which there are a set of articulating metal blades. In normal operation, these are held open by a spring with a fusible link, usually rated somewhere between 165oF to 286oF. However, when a specified temperature is reached, the heat burns through the link and the blades snap shut. Basically, it is a pretty failsafe arrangement.
The dampers are installed in a heating, ventilation or air conditioning (HVAC) duct at – or very near – the point where it passes through a fire-resistant bulkhead. The ideal location is actually embedded in the bulkhead itself where it can create a fireproof seal, so if the ducting falls away, the damper remains solidly in place.
Obviously, fire dampers have been modified and improved over the years and can be pneumatically or electrically operated, defaulting to the closed position if there is a loss of power. They can also double as smoke dampers, the latter very important in passenger vessels as smoke inhalation is usually the biggest killer. Smoke detectors can be linked directly to the actuators. Connecting the dampers to a central fire control board allows the bridge crew to isolate the area around the fire whilst keeping populated areas ventilated.
Electrical management also allows the dampers to be closed ‘dynamically’ against any airflow from an HVAC system. The minimum rating for all dynamic fire dampers is 2,000 ft3 per minute. The dampers can also be opened to allow reverse pressure to be fed into a blazing compartment.
Whilst only larger ships need to fit these dampers by law, increasingly smaller vessels are now carrying them as new builds or installing them as retrofits. This may be partly in response to a spate of dramatic yacht fires in recent years, luckily with no loss of life but with large insurance bills.
In 2019 alone, losses include a 36m Evo 120, berthed in an Italian marina, a 56m USCG cutter conversion, berthed alongside in Thailand and a 33m motoryacht anchored off the Balearics. Whilst the ignition source is often hard to pin down, the majority have been associated with electrical or engine room incidents. In each case, the fire spread rapidly though the vessel and reduced them all to smoking wrecks.
Meeting demand
There are several companies producing fire dampers for a variety of applications, from industry to maritime, and all meet a raft of stringent regulations. MCI is now entering this market for the sub and over 500GT categories aiming fire dampers at luxury yachts and commercial vessels. MCI has recently been given the global distribution rights for the A60 rated fire dampers produced by BSB Engineering. Based in Kent, BSB manufactures nearly all of its components on site, and also adopts green practices in its large factory. The A60 certification is important as it means the dampers have met all the onerous class regulations imposed on charter vessels when it comes to fire-related equipment. As such, BSB’s A60 dampers meet everything from Lloyds Register Approval to the IMO’s Fire test procedures Code.
“The A60 dampers destined for yachts are generally quite a bit smaller than those you would find on commercial ships,” explained BSB’s technical adviser Rowland Cruttenden. “The most popular are the circular models, which can be as small as 100cm across. The largest go up to one metre across. All our models are made from either stainless or galvanised steel, and the blades are aerofoil in section. They are also hollow. This shape helps the flow of the HVAC system in normal use by reducing the pressure drop and fishtails the blades into a tight seal when closed. The heat of a fire causes the blades to expand, and they seal even tighter as a result. The hollow double skin acts as an insulator, and side seals hold back any smoke.”
As with other brands on the market, the dampers can be linked to a fire control system via electric actuators, so the closures can be managed from a central control station. They can also be switched for automatic operation via smoke or heat detectors, or the failsafe fuse link. “It is pretty much impossible to accidentally open a damper once it has shut in an emergency,” Cruttenden said. “But it is possible to override the system if absolutely necessary.”
MCI is choosing to stock the BSB range mainly due to the quick turnaround from order to delivery, but also because of the ability to customise. The yachting industry is very much in that mindset. Each hull tends to be built on a proven engineering platform to reduce construction time, now as little as 18 months for a 40m yacht, with the owner left to create the accommodation to their own design. The ability to customise fire dampers to a specific layout or unique HVAC system not only makes them very attractive in the leisure market, but also in the purpose-built commercial sector.
