AFF-L2.3

Fixed fire-extinguishing systems

AFF-M2 · Controlling the space · AFF-M2-A Ventilation, fuel and electrical isolation, and fixed extinguishing systems.

The biggest decision in yacht firefighting: **releasing a fixed system**, with the arithmetic and the discipline behind it.

Fixed systems

Governing: STCW Code Table A-VI/3; FSS Code chapter 5 (Resolution MSC.206(81)); REG Yacht Code Part A chapter 15A. Builds on: L2.1, L2.2.

The third AFF competence is to inspect and service fire-detection and fire-extinguishing systems and equipment, covering detection, fixed systems, portable and mobile equipment, pumps, rescue and life-support gear, and statutory and classification survey requirements. The criterion is that all of it stays operationally effective at all times.

What a yacht carries

For yachts under 500 GT, REG Part A Table 15A.1 requires a category A machinery space to have a fixed fire-extinguishing system approved to the FSS Code, plus portable extinguishers for oil fires. Yachts of 500 GT and over follow SOLAS II-2/10 via chapter 15B. Common installations:

System Typical use Key hazard
CO2 Engine rooms, generator rooms Lethal to people
Water mist Machinery, accommodation Electrical, visibility
Clean agent Switchboard, AV, server rooms Decomposition products
Sprinklers Accommodation on larger yachts Water damage, stability

FSS Code gas system rules (MSC.206(81))

  • A pre-discharge alarm is activated automatically (for example by opening the release cabinet) and sounds for as long as needed to evacuate, never less than 20 s before release.
  • Controls are readily accessible, simple and grouped where a fire in the protected space will not cut them off.
  • Automatic release is not permitted except as the Administration allows.
  • Two separate controls: one opens the valve to the protected space, the other discharges the bottles, and they can only be worked in that order. Both sit in a release box for that space; if locked, the key is in a break-glass enclosure beside it.
  • For machinery spaces, 85% of the gas can be discharged within 2 minutes.

Worked example: how much CO2?

The Code requires the larger of 40% of the gross volume excluding the casing above the level where its area is 40% or less of the space, or 35% of the gross volume including the casing, with free CO2 at 0.56 m3/kg.

Step Working Result
40% case 0.40 x 330 m3 132 m3
35% case 0.35 x 420 m3 147 m3
Governing volume larger 147 m3
Mass 147 / 0.56 262.5 kg
Within 2 min 0.85 x 262.5 223.1 kg

Knowing this lets you sanity-check the installation and understand why a partially open space defeats the system.

The release decision

  1. Headcount complete and confirmed from the muster.
  2. Space sealed: doors, skylights, vents and fire flaps closed; fans stopped.
  3. Fuel shut and machinery stopped.
  4. Master's order, logged with time.
  5. Release, then leave it sealed. Monitor boundary temperatures and keep cooling.

WARNING - Premature re-entry Opening the space too early lets air reach hot metal and fuel, and the fire comes back with the CO2 gone. Plan re-entry with BA, charged hoses and a ventilation route that takes gas away from people.

Inspection and survey

Weekly and monthly checks follow the planned maintenance system and the manufacturer; annual servicing and bottle checks are by approved service firms; flag and class survey the installation. Keep records ready for survey and port state control.

Practice questions

5 questions

recall · core

Under the FSS Code, the pre-discharge alarm for a fixed gas system must sound for no less than: (a) 20 s (b) 60 s (c) 5 s (d) 10 s

recall · core

For machinery spaces, the CO2 piping must allow what proportion of the gas to be discharged within 2 minutes? (a) 50% (b) 75% (c) 85% (d) 100%

recall · core

A machinery space has a gross volume of 420 m3 including casing and 330 m3 excluding the casing. Using the FSS Code, the minimum CO2 is about: (a) 236 kg (b) 263 kg (c) 147 kg (d) 330 kg

recall · core

What must happen before a fixed CO2 system is released into an engine room? (a) The fire must be confirmed extinguished (b) Shore authorities must approve (c) The space must be ventilated (d) Everyone accounted for, the space sealed, ventilation and fuel stopped, and the master's order given

scenario · core

Twenty minutes after a successful CO2 release into the engine room, the chief engineer wants to open the door to check. Boundary temperatures are still falling slowly. What do you decide? (a) Open the door now to inspect (b) Keep the space sealed, continue boundary monitoring and cooling, and plan re-entry later with BA, charged hoses and ventilation arranged to clear gas away from people (c) Restart the engine room fans (d) Release a second bank immediately

Independent study. xplor is not an accredited training provider and awards no certificate or Certificate of Competency. The AFF certificate of proficiency is issued only after completing the practical course, including live fire and breathing apparatus exercises, at an MCA-approved training provider. AI-drafted content pending subject-matter-expert review.