Sprinkler Protection for Cloud Ceilings. Jason Floyd *, Steve Strege, and Matt Benfer JENSEN HUGHES,

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1 Sprinkler Protection for Cloud Ceilings Jason Floyd *, Steve Strege, and Matt Benfer JENSEN HUGHES, Gaetano Coppola HUGHES ASSOCIATES EUROPE Cloud ceilings are increasingly seen in commercial and industrial facilities. The ceilings consist of ceiling panels separated by gaps that are suspended beneath the structural ceiling. Designs for cloud ceilings can vary greatly in terms of the shape and size of the panels, the gaps between panels, and the spacing between the panels and the structural ceiling. The use of cloud ceilings presents challenges for sprinkler protection that are not definitively addressed in NFPA 13. These challenges result from 1) heat from the fire plume entering the gaps between the panels and rising to the structural ceiling which may prevent sprinklers below the clouds from activating, and 2) that sprinklers above the clouds may have their spray distribution blocked by the clouds. As a result, in some conditions the code would require sprinklers both below the clouds and at the structural ceiling. This is undesirable and a preferable solution would be to only install sprinklers below the clouds if possible. In order to develop guidance for sprinkler protection for cloud ceilings, the Fire Protection Research Foundation funded a two-phase project to investigate sprinkler performance for cloud ceilings. The first phase studied large, non-combustible, co-planar clouds. For this phase large means that the area of the cloud is similar to or greater than the coverage are for a sprinkler (e.g. each cloud would require a sprinkler beneath it). The second phase studied small, non-combustible, co-planar clouds. For both phases, the Fire Dynamics Simulator was used to simulate a range of geometries and fire locations. Variables included the fire location, fire growth rate, cloud-to-cloud gap size, cloud size, floor-to-cloud height, and ceiling plenum height. Each phase included a brief experimental study used to develop and validate the modeling approach. For each simulation, an assessment was made of the below cloud sprinkler performance. Performance was evaluated using a set of performance criteria based on the UL-1626 residential sprinkler acceptance test requirements. Results of the simulation were used to develop a set of installation guidelines on permissible below cloud sprinkler spacing given the ceiling height and cloud geometry.

2 Sprinkler Protection for Cloud Ceilings 1

Background and Motivation Cloud ceilings are a popular architectural feature Lack of clear guidance in NFPA 13 Clouds often don t meet concealed space

3 Background and Motivation Cloud ceilings are a popular architectural feature Lack of clear guidance in NFPA 13 Clouds often don t meet concealed space requirements for the structural ceiling Clouds generally pose significant obstructions to sprinklers above the clouds Where should sprinklers be placed? nei.org

project to evaluate sprinkler protection for cloud ceilings

4 Background and Motivation ecophon.com armstrong.com In 2012 Fire Protection Research Foundation began a two phase project to evaluate sprinkler protection for cloud ceilings Efforts in both phases were limited to noncombustible clouds beneath non-combustible ceilings

5 Project Phases Phase 1: Large Contiguous Clouds (Cloud dimension >= sprinkler spacing) Task 1: Literature Review Task 2: Small Scale Experiments + FDS Validation Task 3: Numerical Large Scale Experiments Phase 2: Small Clouds Task 1: Small Scale Experiments + FDS Validation Task 2: Numerical Large Scale Experiments

5 m cloud = 10 cm gap Perforated Ceilings If free area of the perforation >10 %, then impacts on

6 Phase 1 (Task 1): Literature Review Little directly applicable research Roof vents If free area of the vents < 4 % of the ceiling area, then little impact on sprinkler activation. For a 4.5 m x 4.5 m cloud = 10 cm gap Perforated Ceilings If free area of the perforation >10 %, then impacts on smoke detection and sprinkler operation are seen. For a 4.5 m x 4.5 m cloud = 30 cm gap bilco.com archexpo.com

7 Phase 1 (Task 2): Experimental Program Primary goal validation of FDS modeling approach Suspended two 2.4 m x 2.4 m clouds with a 15 cm Two 2.4 m x 2.4 m moveable walls Cloud-Cloud Slot Cloud-Wall Cloud-Corner Wall Cloud Fire Ceiling Cloud-Cloud-Wall

8 Phase 1 (Task 2): Experimental Program Fire 0.01 m 2 propane sand burner Thermocouples 5 cm below the clouds and structural ceiling Residential quick response sprinkler pressurized with air on one cloud (request of project technical panel) TC Location Sprinkler

9 Phase 1 (Task 2): Experimental Program FDS 6 Release Candidate 1 St ruct ural Cloud All Dat a s=0.39 d=1.21 s=0.39 d=0.94 s=0.41 d=1.0 8

10 Varies Phase 1 (Task 3): Numerical Expirements Grid study - 3 to 5 cells are needed across the gap Growth rate medium, fast Ceiling height 2.4, 4.3, 6.1, and 10.4 m Plenum height 0.6 m and 1.2 m Gap size Begin with 6.25 % and 12.5 % of ceiling height based on literature review. Adjust based on results Wall Cloud Fire Cloud Panel 0.61 m (2 ft) Door 9.1 m (30 ft) Cloud-Cloud Slot Cloud-Cloud Cross 4.6 m (15 Cloud-Wall Slot Cloud-Corner Cloud-Cloud-Wall

11 Evaluating Results of Simulations Establish performance criteria for sprinklers NFPA 13: Establish criteria to protect life and property

12 Evaluating Results of Simulations Sprinklers operated by fire plume if sprinklers operate via the layer may operate sprinklers away from the fire 1.6 m above the floor must remain < 93 C away and not exceed 54 C for over two minutes keep conditions tenable for egress Below the either the structural ceiling or the cloud ceiling < 315 C at a distance of 50 % of the sprinkler spacing avoid formation of a hot layer that could cause injury or ignition of remote materials Backside temperatures of the structural and cloud ceilings < 200 C This is to avoid significant damage to the structural ceiling or failure of supports for the cloud ceiling

13 Plume vs. Layer 1 st sprinkler due to plume 1 st sprinkler due to layer

14 2.4 m height to clouds Failure Borderline

15 Phase 1: Recommendations (Task 3) For non-combustible clouds below non-combustible ceilings where the cloud is large enough where each cloud will have at least on sprinkler, then clouds on the structural ceiling can be omitted if Single-part rule: The gap between a wall and any cloud or between two adjacent clouds is less than or equal to 8 cm per meter of ceiling height Two-part rule: The gap between a wall and any cloud is less than or equal to 8 cm per meter of ceiling height, or The gap between any two adjacent clouds is less than or equal to 10 cm per meter of ceiling height.

16 Phase 2 (Task 1): Small Scale Experiments 8 ft 2 ft Structural Ceiling Cloud TC (2 below both clouds and structural ceiling) Fire Location

17 Predicted Temperature ( C) Predicted Temperature ( C) Predicted Temperature ( C) Phase 2 (Task 1): Small Scale Experiments s=0.11 d=1.0 1 All Data s=0.11 d=0.97 Cloud Data Movable Ceiling Data s=0.10 d= Measured Temperature ( C) Measured Temperature ( C) Measured Temperature ( C)