2 Definitions
Clasification Society 2024 - Version 9.40
Statutory Documents - IMO Publications and Documents - Circulars - Maritime Safety Committee - MSC.1/Circular.1430 – Revised Guidelines for the Design and Approval of Fixed Water-Based Fire-Fighting Systems for Ro-Ro Spaces and Special Category Spaces – (31 May 2012) - Annex – Revised Guidelines for the Design and Approval of Fixed Water-Based Fire-Fighting Systems for Ro-Ro Spaces and Special Category Spaces - 2 Definitions

2 Definitions

  2.1 Area of operation is a design area for wet-pipe, automatic sprinkler system (to be determined for performance-based systems by the test procedure described in the appendix to these Guidelines).

  2.2 Automatic sprinkler or nozzle is a single or multiple orifice water discharge device that activates automatically when its heat-activated element is heated to its thermal rating or above, allowing water under pressure to discharge in a specific, directional discharge pattern.

  2.3 Automatic system is a system utilizing either automatic sprinklers or nozzles or a system that is automatically activated by a fire detection system.

  2.4 Deluge system, automatic and manual release is a system employing open nozzles attached to a piping system connected to a water supply through a valve that can be opened by signals from a fire detection system and by manual operation. When this valve is opened, water flows into the piping system and discharges from all nozzles attached thereto.

  2.5 Deluge system, manual release is a system employing open nozzles attached to a piping system connected to a water supply through a valve that is opened by manual operation. When this valve is opened, water flows into the piping system and discharges from all nozzles attached thereto.

  2.6 Dry pipe system is a system employing automatic sprinklers or nozzles attached to a piping system containing air or nitrogen under pressure, the release of which (as from the activation of a sprinkler or nozzle by heat from a fire) permits the water pressure to open a valve known as a dry pipe valve. The water then flows into the piping and discharges from the open nozzles or sprinklers.

  2.7 Fire control limits the size of a fire by distribution of water so as to decrease the heat release rate, while controlling ceiling gas temperatures and pre-wetting adjacent combustibles and/or reducing heat radiation to avoid structural damage.

  2.8 Fire suppression is the sharp reduction of the heat release rate of a fire and the prevention of regrowth.

  2.9 K-factor is a sprinkler nozzle discharge coefficient determined by testing, that is used to calculate flow rate at any given pressure through the relationship , where Q is the flow rate in litres per minute, and P is the pressure in bars.

  2.10 Open sprinkler or nozzle is an open single or multiple orifice water discharge device that, when discharging water under pressure, will distribute the water in a specific, directional discharge pattern.

  2.11 Performance based requirements are based on the results of fire tests conducted on specific nozzle design and arrangements. The required engineering parameters for such systems are determined by the results of the fire tests.

  2.12 Prescriptive based requirements are specific requirements, such as minimum water discharge density or maximum nozzle spacing, and are applied equally to all systems designed to this approach.

  2.13 Pump means a single water pump, with its associated driver and control or an individual pump within a pump unit.

  2.14 Pump unit means a single water pump, or two or more pumps connected together to form a unit, with their associated driver(s) and controls.

  2.15 Pre-action system is a system employing automatic sprinklers or nozzles attached to a piping system containing air that may or may not be under pressure, with a supplemental fire detection system installed in the same area as the sprinklers or nozzles. Activation of the fire detection system opens a valve that permits water to flow into the system piping and to be discharged from any sprinkler or nozzle that has operated.

  2.16 Water-based extinguishing medium is fresh water or seawater, with or without an antifreeze solution and/or additives to enhance fire-extinguishing capability.

  2.17 Water discharge density is the unit rate of water application to an area or surface expressed in mm/min (equal to (l/min)/m2).

  2.18 Wet pipe system is a system employing automatic sprinklers or nozzles attached to a piping system containing water and connected to a water supply so that water discharges immediately from sprinklers or nozzles opened by heat from a fire.

Parent topic: Annex – Revised Guidelines for the Design and Approval of Fixed Water-Based Fire-Fighting Systems for Ro-Ro Spaces and Special Category Spaces
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