2. Should We Model Sprinkler Cooling? Presented by: Ben Hume Kevin Weller

3. What’s the starting point? Don’t model sprinklers..

4. Why? “We don’t have enough data to accurately model sprinklers” “Modelling sprinkler cooling increases the level of error” “Other factors have a greater impact (HRR, Material, Modelled Space)”

5. So what we’re really saying is…. Modelling a fire with no sprinklers is more accurate (less error) than modelling a fire with sprinklers…..and there are more aspects to worry about….

6. Is this the case though? Sprinklers impact: –Upper layer temperature, hence volume, density and buoyancy –Down drag (typically local though and not a threat to occupants )

7. Literature Review Error 10-15% for temperature 7% -8% for velocity N. O’Grady and V. Novozhilov - 2008 Large Eddy Simulation of Sprinkler Integration with a fire ceiling jet

8. Literature Review S.C.Li et al. - 2008 Studies of Cooling Effects of Sprinkler Spray on Smoke Layer

9. Proof of Concept 3D smoke view image of slice through FDS with no sprinkler so we can see the sprinkler and the smoke layer. Want to show how thin the layer is.

10. Sprinkler Inputs Particle diameter – 500μm Particle velocity – 5.58ms -1 RTI – 135 m 1/2 s 1/2 C – 0.85 m 1/2 s 1/2 T act – 68 o C

11. Spray Angle Common Use Pyrosim Default N. O’Grady & V. Novozhilov

12. Results – Spray Angle FDS no sprinkler Experiment no sprinkler Experiment Sprinkler 50, 60, 75Lpm

13. Results – Spray Angle

15. Results – Flow Rate

17. Resulting Sprinkler Input Velocity – 5.58ms -1 Spray Angle – 65 o -115 o Droplet size – 500μm RTI – 135 m 1/2 s 1/2 C – 0.85 m 1/2 s 1/2 T act – 68 o C

18. What impact on modelling do sprinklers have

19. Small Room Temperature (upper layer)

20. Visibility @ 2m Small Room

21. Medium Room Temperature

22. Large Room Temperature

23. Large Room Visibility * At 2 m

24. Other factors Material (Medium Room) Plasterboard

25. Other factors Material (Medium Room) Plasterboard Concrete

26. Other factors Material (Medium Room) Plasterboard Concrete Steel

27. Other factors Material (Medium Room) Plasterboard Concrete Steel Inert

28. Other factors Material (Medium Room) Plasterboard Concrete Steel Inert Adiabatic

29. Visibility @ 200s Other factors: Structure Graph of temperatures FDS and B-Risk

30. Other factors: Structure Visibility @ 500s Graph of temperatures FDS and B-Risk

31. Summary AspectTemperatureVisibility MaterialsMinimal StructureMinimalModerate Room ShapeTemperatureVisibility SmallSignificantMinimal MediumSignificantModerate LargeModerate Sprinkler Impact – Room Size Other Aspects Impact

32. Cooling and C/VM2? Perception: “C/VM2 was developed without consideration of cooling” Interpretation: No formal guidance Use your engineering judgement

33. Recommendations The error of not modelling sprinklers is greater than the error introduced by modelling them. Sprinklers should be considered when: –The space is Medium - Large –There are complex flow paths (Buoyancy driven interactions) –Natural or mechanical ventilation exists

34. Recommendations The use of Brisk over FDS should be reconsidered even when within accepted bounds where : –the above conditions exist and sprinklers should be considered –there is significant structure/complex flows (i.e. large warehouses with lattice beams or solid beams) Surface finishes and structure have significant impacts in models but less impact than sprinklers