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Fixed Fire Suppression
Fixed Fire Suppression covers clean agent and inert gas total flooding systems, high and low-pressure water mist, local application systems and galley fryer systems for enclosed spaces on rigs and vessels. Each is approved as a complete design with its own nozzles, valves and design manual. A used system keeps its value only if it is complete or matches an installed system part for part. CO2 has its own sub-Category.
How the system types put out a fire
Clean agent systems discharge a halocarbon such as HFC-227ea or FK-5-1-12 into a closed space. The agent removes heat and interrupts the combustion chemistry, and leaves no residue on electronics. Inert gas systems such as IG-541 and IG-55 dilute the oxygen in the room to a level that will not support flame. Water mist systems spray very fine droplets that cool the fire and displace oxygen locally with steam, using far less water than sprinklers. Local application systems are water-based systems aimed at high-risk spots inside a large machinery space, and you can release them without evacuating the space.
Configurations
| Type | Typical storage | Where it fits |
|---|---|---|
| Halocarbon clean agent | Liquid in containers superpressurised with nitrogen, commonly 25 or 42 bar | Switchboard, control and electronics rooms |
| Inert gas | Gas in cylinders at 200 or 300 bar | Electrical rooms, larger enclosed spaces |
| High-pressure water mist | Pump skid or cylinders, high-pressure stainless pipe | Machinery spaces, generator enclosures |
| Low-pressure water mist | Pump skid, larger pipe | Machinery and accommodation spaces |
| Local application | Water mist or spray on the fire main or own skid | Engine tops, purifiers, boiler fronts |
| Galley fryer system | Wet chemical cylinder | Deep-fat fryers and hood ducts |
Key specifications
| Parameter | Why it matters | Typical units |
|---|---|---|
| Protected volume and design concentration | Sets agent quantity and cylinder count | m3 or ft3, percent by volume |
| Discharge time | Approval criteria for each agent type | Seconds |
| Storage pressure | Cylinder and valve class | bar or psi |
| Nozzle type and count | Fixed by the approved design manual | Model, quantity |
| Pump flow and pressure, for mist | Covers the largest section | L/min, bar |
Standards and approvals
- Chapter 5 of the FSS Code covers fixed gas systems. MSC/Circ.848, as amended by MSC.1/Circ.1267, sets approval of halocarbon and inert gas systems for machinery spaces. Halocarbons must reach 95 percent of design concentration within 10 seconds, and inert gases 85 percent within 2 minutes.
- Chapter 7 of the FSS Code covers water mist. MSC/Circ.1165 as amended sets approval of water mist systems that replace gas in machinery spaces.
- MSC/Circ.913 sets approval of local application systems. SOLAS chapter II-2 regulation 10.5.6 requires them in category A machinery spaces above 500 m3 on cargo ships of 2,000 gross tonnage and above.
- SOLAS chapter II-2 regulation 10.6.4 asks for a fixed system on deep-fat cooking equipment, approved to ISO 15371.
- NFPA 2001 and ISO 14520 cover clean agent design, and NFPA 750 covers water mist, on units built to those codes.
The type approval certificate names the maker's design manual and its limits. Check that it is current and that the system was built inside them.
Agent supply and environmental rules
3M has stopped making Novec 1230. FK-5-1-12 is still sold by other producers, but the system approval must cover the agent you refill with. HFC-227ea falls under HFC phase-down in the EU and under the Kigali Amendment. Inert gas and water mist carry no such supply risk. Halon has been banned from new installations under SOLAS for decades.
Failure modes and inspection
- Container contents, checked by weight or liquid level gauge for halocarbons and by pressure for inert gas
- Cylinder and container hydrostatic test dates
- Discharge valves, actuators, pilot cylinders and flexible hoses
- Nozzle blockage and corrosion, especially fine mist orifices
- Mist pump unit hours, strainers and fresh water supply
- Room integrity, tested by door fan for hold time on gas systems
- Release panel, time delay and pre-discharge alarms
Documentation
- Type approval certificate and design manual reference
- Hydraulic flow calculation and as-built isometrics
- Cylinder certificates and test dates
- Commissioning and last service reports
- Room integrity test results for gas systems
Integration and compatibility
A gas system needs a room that holds its concentration, ventilation shutdown on release and safe access for the people who must leave first. The release panel must take signals from your fire detection and talk to your fire and gas logic. Mist systems need fresh water and a power supply rated for the pump. Pipe runs must stay within the design manual's limits on length, height and fittings.
Refurbishment and buying used
A complete unused package from a cancelled project, with its calculations, is the best surplus buy. Used systems make most sense as spares for an identical installation. Recertification means retesting cylinders that are due, refilling with an approved agent, new seals and hoses, and a full function test. Naventr can arrange an inspection of a system on request. Marioff and Danfoss Fire Safety are known for marine water mist, and Kidde and Minimax supply gas systems. For machinery spaces where CO2 is still the norm, see foam and CO2 systems.
FAQ
Frequently asked questions
Can I buy a used FM-200 or Novec 1230 system for a rig?
Yes, if the system is complete and its marine type approval is still valid. The approval covers the whole design, so mismatched nozzles or valves can void it. 3M has stopped making Novec 1230, so confirm that the approval covers an FK-5-1-12 agent you can buy.
Which IMO rules apply to water mist systems in machinery spaces?
IMO MSC/Circ.1165, as amended by later circulars, sets approval of water mist systems that replace gas in machinery spaces. Chapter 7 of the FSS Code applies. Local application systems are approved under MSC/Circ.913.
When is a local application fire system required?
SOLAS chapter II-2 regulation 10.5.6 requires one in category A machinery spaces above 500 m3 on cargo ships of 2,000 gross tonnage and above. It protects engine tops, purifiers and boiler fronts and can be released without evacuating the space.
How fast must a clean agent system discharge?
Under MSC/Circ.848 as amended, a halocarbon system must reach 95 percent of its design concentration within 10 seconds. An inert gas system must reach 85 percent within 2 minutes. A used system must still meet these with your pipework.
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