FSS Code Chapter 5: Fixed Gas Fire-Extinguishing Systems
Carbon dioxide quantity and discharge rate, controls, alarms, and why the ventilation shutdown duty is not in the FSS Code.
Chapter 5 of the International Code for Fire Safety Systems governs fixed gas fire-extinguishing systems. The Code was adopted by resolution MSC.98(73) on 5 December 2000 and took effect on 1 July 2002; chapter 5 was subsequently replaced in full by resolution MSC.206(81), adopted 18 May 2006 and in force 1 July 2010.
The chapter sets two separate rules that are routinely merged into one wrong figure. Paragraph 2.2.1.2 sets the carbon dioxide quantity for machinery spaces at the larger of 40 percent of the gross volume of the largest machinery space protected, excluding the upper casing on a stated test, or 35 percent including the casing, with paragraph 2.2.1.1 setting 30 percent for cargo spaces. Paragraph 2.2.1.5 separately requires that 85 percent of the gas be dischargeable within 2 minutes for machinery spaces.
The article will also make a negative point that matters operationally. Chapter 5 contains no ventilation or damper provision at all: the duty to stop ventilation and close dampers before release comes from SOLAS regulations II-2/5.2.2.1 and 5.2.2.2. The only pre-discharge timing requirement in the chapter is the alarm at paragraph 2.1.3.2, sounding in no case less than 20 seconds before release.