The Motorship | The benefits of DESMI onboard firefighting systems

The DESMI FineFog™ firefighting system has several advantages over CO2-based total flooding, including fast, safe, localized application.

In marine applications, DESMI’s FineFog™ Fixed Water-Based Firefighting systems offer a safe, low-pressure alternative. After years of success in Asian-built ships, DESMI is now bringing its efficient firefighting products to the European market.

In Asia, DESMI is known not only for its pumps but also for its firefighting systems. More than 180 such systems are supplied to ship owners around the globe – though most of these are for ships built in China. There have not been so many installations in European shipyards, so DESMI’s Marine and Offshore Sales Manager, Christian Mellergaard wants to reach out to European ship owners and shipyards to change this.

“They mainly know us for our pumps and might not know we offer these highly efficient firefighting systems – which of course include our pumps and offer some great advantages,” he says.

DESMI has the following types of firefighting systems available:

• Fixed water-based local application system for machinery space
•  
• Equivalent water mist fire extinguishing system for total flooding in machinery spaces and cargo pump rooms
• Water sprinkler system for accommodation
• Deck foam system for oil/chemical tanker deck protection
• Foam system for deck and helicopter landing areas
• Water spray/deluge/drencher system for special category spaces.

The benefits of FineFog™

For machinery spaces, DESMI offers its low-pressure, water-based FineFog™ system. FineFog™ dispenses a mist – like a fog. “You can kill the fire much easier with mist than by just pouring water on it. These millions of small droplets absorb much more heat, and oxygen is displaced locally at fire source. As a result, an inerting effect is generated, effectively killing the fire,” Christian says.

Ships will benefit from the automatic system around high-risk objects like combustion machinery, oil-fired boilers or burners, incinerators or purifiers for heated oil fuel. If there is an oil spill that catches fire, then the FineFog™ nozzles above that application are activated – based on a signal from flame detector or smoke detector – and the alarm sounds. The crew can still enter the room and continue with conventional firefighting with hoses. Or, if necessary, they can release the total flooding mechanism in engine rooms up to 5036 m³.

“And that’s where our system has a big advantage over gas-based firefighting systems like CO₂,” Christian says. While CO₂ systems are effective, they come with a risk to human life. “With CO₂, if you have a fire on your engine room, you first need to evacuate everybody because otherwise the gas will suffocate them. And you have to make sure ventilation is shut off, and the room is completely sealed off. You must also ensure that all machinery in the engine room is stopped. This can take several minutes. In this time, a minor fire can grow quite large,” he says. “You only have one shot with CO₂ – you can only release the system once. And also, CO₂ has no cooling effect. So that actually means, the fire could reignite very easily. And afterward, you can’t go into the engine room or confined space for several hours. You need to be totally sure that the fire is put out first before restarting ventilation of the engine room.”

DESMI’s FineFog™ total flooding by water mist offers a great alternative. “You can just start it right away. You can activate the main system, and people can be present, if needed – it doesn’t kill them. It’s just water. And it’s non-toxic. And there’s plenty of it. At the same time, you have the cooling effects. That’s one of the big advantages. It’s effective, it only uses minimal flow rates, and it’s easy.  Pump from a freshwater tank or sea chest. The maintenance is easy compared to the regular inspections you need to do with CO₂ installations. And you don’t need extra room for all these CO₂ bottles.”

Image: The FineFog™ kills the fire with millions of tiny droplets of water, absorbing heat and oxygen.

Protecting accommodation areas

For living areas, hallways, and other accommodation areas like cafeterias, DESMI offers its automatic water sprinkler system. The most common is a conventional wet-pipe system, meaning the piping is filled with pressurized water from a dependable source. It runs with low pressure.

It starts locally – Only sprinklers above or adjacent to the fire are activated to avoid water damage. “It’s very effective. In most cases, it will kill the fire in a very short time and maybe only with two or three sprinklers active.”

A similar, dry pipe system is available for areas where the water in the piping would be subject to freezing. In such a system, air or nitrogen fills the pipes until a fire activates the sprinklers. In that case, air escapes from the pipes and activates the dry pipe valve, causing water to flow from the activated sprinklers.

Image: The water sprinkler system for accommodation can in most cases kill the fire in a very short time with only a few sprinklers active.

Low expansion foam

DESMI’s low expansion foam firefighting system protects oil and chemical tanker deck areas, helidecks, or other open deck areas (like loading areas) and closed, horizontal spaces like streamer reel and purifier room. Water will not kill an oil fire. Instead you can apply foam, and this will form a ‘floating blanket.’ There is no vapor from the oil and the foam also cools the area.

The pressurized foam is delivered by a foam pump or from a tank to a mixing device. Then it is aerated and sprayed directly onto the areas of the fire.

Images: DESMI low-expansion foam firefighting system

Water spray system

DESMI also offers a water spray/deluge/drencher system with open nozzles. It is activated by a fire detection system, opening a deluge valve and letting water flow simultaneously from all the open sprinklers in a specific section. Deluge systems are used for protection against rapidly spreading, high-hazard fires on for example RO-RO and RO-PAX vessels.

Image: Deluge system working on a ferry car deck

Water spray is used to cool fires, and for crew protection on for example gas carriers or chemical tankers, where you cool down the whole deck area and surfaces with water spray. Water spray is also required on vessels transporting class 1 material like containers and open hatch general cargo vessels.

Images: Water spray systems (white piping) for gas carrier and chemical tanker PO deck area.

For self-unloading vessels, water spray is used to kill or suppress fires in material and offloading equipment. Systems can also be installed for dust suppression on these self-unloading vessels.

Images: Water spray in use at a C-Loop system for self-offloading vessel dust suppression, outside and inside views.

The low-pressure advantage

Christian Mellergaard says that of all the advantages of the DESMI firefighting system, the biggest is a low-pressure (max 16-bar) system. “It’s easy to install and you can use galvanized piping, which is cheaper. It’s high precision, the maintenance is easier. This is where DESMI has an advantage over many of the other systems.”

In addition, up-to-date development ensures rule compliance and system reliability.

These include regulations from the International Maritime Organization’s Maritime Safety Committee (MSC), the international convention for Safety of Life at Sea (SOLAS) and other regulations from Classification and Flag Authorities.

Plus, he adds, the system is designed with DESMI’s own pumps and controls in mind. “So, we calculate the pump sizes and design the system and make the drawings for the shipyards. And as you know, there are a lot of pumps on a vessel. DESMI can supply these, too. So, we can make an attractive package offer for both pumps and fire system.”