Clean agent system Design metholody.pptx

Design of clean agent systems

1. Clean Agent Design to NFPA 2001

2. System Overview Definition Types 1 2 3 Table of Contents Volume Sizing 4 Pipe Sizing 5

3. System Overview Smoke Detectors Control Panel Notification Devices Release Devices Cylinders Nozzles Abort switches Maintenance switch Manual Release

4. Definition of Clean Agents A clean agent is a gaseous fire suppressant that is electrically non-conducting and that does not leave a residue upon evaporation. They are Total flooding systems Used in: To protect high value facilities per volume e.g Data processing facilities Telecommunication facilities Art storage facilities etc Extinguish by: Increasing the heat loss from the fire by increasing the heat capacity of the environment within the protected enclosure. Displacing the oxygen in the environment within the protected enclosure. For the halocarbon agents, absorbing energy from the fire to cause decomposition of the agent

5. Types of Clean Agents Consist of either halocarbons or inert gases. Halocarbons: HFC-227ea (FM-200) HFC-125 (FE-25) FK-5-1-12 ( Novec 1230) Uses the agent-decomposition mechanism to cause extinguishment. This mechanism results in lower agent design concentrations for this group of agents. As the products formed by decomposition of the agent are toxic (primarily HF), caution must be used and appropriate protective equipment should be worn when re-entering a protected space after a fire event. The amount of decomposition products formed is directly related to the size of the fire at the time of system activation. Early detection and prompt system activation are key for limiting the amount of decomposition products formed. They have high GWP (except for Novec1230 which has a low GWP)

6. Types of Clean Agents Inert Gases: IG-100 (nitrogen) IG-01 (argon) IG-55 ( Argonite ) IG-541 ( Inergen ) Do not undergo the agent-decomposition reaction Thus higher design concentrations than the halocarbon agents. Less expensive on a mass basis. However, larger quantities of inert gases would be needed.

7. GWP of various Clean Agents

8. Clean Agent Design Concentrations Minimum and maximum design concentration Minimum Design Concentration: Based minimum extinguishing concentration with a safety factor between 20% and 30% applied Min. design concentrations for a given agent are determined based on the hazard class (A, B, or C) of the fuel and the actual fuel present

9. Maximum Design Concentration Normally occupied spaces Halocarbon agents Design conc. Up to no observable adverse effect level (NOAEL) max. of 5mins exposure duration for. Inert Gases Up to 43% (12% oxygen level) for max exposure time of 5mins or Up to 52% (10% oxygen level) for max. exposure time of 3min Normally unoccupied spaces

10. Hazard Classification Normally unoccupied spaces Halocarbon agents Design conc. Up to lowest observable adverse effect level (NOAEL) max. of 1mins exposure duration. Design concentrations exceeding the LOAEL are permitted with the max. exposure time of 30 secs. HFC-227ea and HFC-125 are permitted up to 10.5% and 11.5% with a max. exposure time of 5 min. Higher concentrations would be permissible with shorter maximum-exposure times as specified in section 1.5.1.2 of NFPA 2001. Inert gas agents: Design concentrations of up to 62%, (8% oxygen level) max. egress time not exceeding 30 secs. Unoccupied spaces: (No restrictions)

11. Exposure Time for different Concentrations

12. Exposure Time for different Concentrations

13. NOAEL & LOAEL for Halocarbons

14. 2 Design calculations For Halocarbons: For Inert gases:

15. Design calculations

16. FM 200 Sizing Sheet

17. IG-55 Sizing Sheet

18. Pipe Sizing It is not accurate to design pipe sizing by hand since it involves two-phase flow. There is the existence of gas and liquid phases simultaneously in the pipe network. Coupled with the relatively short flow times results in significant challenges to correctly predicting the flow

19. Discharge Profile

20. Discharge Profile