Instantly effective

The installation of water-based fixed local application fire-fighting systems in newbuildings is no longer a matter of choice. Indeed, for all passenger ships of 500 gross tonnage plus and all cargo ships of 2,000 gross tonnage plus constructed since 1 July 2002, such a system must be provided in all category A machinery spaces over 500m3. Furthermore, by 1 October next year this regulation will also apply to all passenger vessels of 2,000 gross tonnage and above built before 1 July 2002.

Guidelines state that fixed local application fire-fighting systems (in addition to main CO2 or other flooding fire fighting systems) are to protect areas such as the following without the necessity of engine shutdown, personnel evacuation, or sealing of the spaces: the fire hazard portions of internal combustion machinery used for the ship’s main propulsion and power generation; boiler fronts; the fire hazard portions of incinerators; and purifiers for heated fuel oil.

A further improvement is the use of high pressure water mist for both total flooding and local application. When you consider the drawbacks of other types of total flooding fire-fighting systems, such as a gaseous (CO2) total flooding system, the reason for such measures is clear. For a start, before a CO2 system can be activated engines need to be shut off, the machinery space needs to be evacuated, all openings and vent need to be shut and total evacuation has to be verified. “Consequently it can take 20 minutes or longer from the time a fire is first spotted until such a system can be activated,” explains Stefan Gordin, Vice President of the Marine Division at Marioff ? the pioneer of water mist systems. Such delay not only allows a fire to spread freely causing considerable danger to personnel and damage to equipment, but also causes a vessel to lose manoeuvrability.

A total flooding system, however, such as the HI-FOG water-mist system offered by Finland-based Marioff, is not harmful to personnel and can be activated immediately to quickly extinguish a fire and limit such damage and danger. Consequently, the best policy in such a situation is, as Gordin eloquently puts it, “don?t wait, activate”.

Alternative

The HI-FOG technology is the brainchild of Marioff?s founder Göran Sundholm and was developed in the early 90s as an alternative to conventional sprinkler fire protection. The system has more recently been further developed for a wide range of protection, including total flooding and local application in machinery space, as well as ducts and deep fat fryers. “While the last may be a relatively minor application,” adds Gordin, “many fires onboard ships actually start in the deep fat fryer.”

Using only water with no chemical additives for a combination of cooling and oxygen depletion, HI-FOG offers a safer, cleaner alternative to other fire extinguishing agents, particularly with regard to a total flooding system.

“It is safer than carbon dioxide which is lethal, does not harm the environment like the banned agent Halon and does not create the mess and subsequent clean up operation of foam,” says Gordin. The system can be returned to standby without the need to visit a port and the ship is back in operation in very little time.

One of the fully approved HI-FOG local application systems comprises widely spaced spray heads connected by small-bore stainless steel tubes to a self-contained GPU (Gas driven Pump Unit) requiring no external power.

Alternative

ly, an electrically or diesel driven pump can also be provided. “Because it requires only a small amount of water and therefore uses smaller pipes,” explains Gordin, “installation of the system is made easier by less weight and the use of progressive cutting ring fitting, so savings can be made which help bring down the total cost.” Also, the system?s nozzles can be spaced up to 5m apart at ceiling level and with fewer nozzles and well spaced pipework, the system will not impede normal operations and maintenance in the engine room.

Advantages

HI-FOG uses state-of-the-art nozzle technology together with high-pressure pump or cylinder power units to ensure small water droplets and high spray momentum.

This provides excellent fire suppression with minimal water usage. With regard to extinguishing capability, it also does not depend on enclosure integrity being maintained like a gaseous system and can also extinguish liquid fuel and spray fires, as well as hidden fires unlike conventional sprinkler systems.

Other advantages in terms of fire protection include, because of the small droplet size, efficient vapourisation of water leading to high-energy absorbtion and gas cooling, which prevents flashover and re-ignition. The system also provides effective radiant heat blocking.

Importantly, the system?s efficiency results in minimal fire damage. In tests 7,000 litres of water used by a conventional sprinkler system to put out a fire resulted in more than 50% damage. With the HI-FOG system only 150 litres of water were used to extinguish the same fire and damage was put at less than 1%.

In conculsion, while the matter of installing a water-based fire protection system may not now be up for debate, the choice of which system to actually install and results such as these that indicate distinct advantages of certain systems must surely be carefully considered by shipowners. n