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Comparison of sprinkler activation times under flat and corrugated metal deck ceiling

Runefors, Marcus LU orcid ; Boström, Per and Almgren, Erik (2018) 3rd European Symposium on Fire Safety Science, ESFSS 2018 In Journal of Physics: Conference Series 1107.
Abstract

The distance of sprinklers below ceiling is of fundamental importance since it has a great influence on activation time. Accepted distances are specified in different sprinkler standards such as NFPA 13, FM 2-0 and EN 12845 for different configurations. This distance is unambiguously defined for flat smooth ceilings, but for corrugated ceilings, such as corrugated metal deck ceilings found in many warehouses, the distance can be measured from either the top or the bottom of the deck. NFPA 13 states that it should be measured from the bottom if the thickness of the deck is below 75 mm and from the top if it is higher. The requirement in NFPA 13 has been adopted from the FM datasheets, but the authors have been unable to identify any... (More)

The distance of sprinklers below ceiling is of fundamental importance since it has a great influence on activation time. Accepted distances are specified in different sprinkler standards such as NFPA 13, FM 2-0 and EN 12845 for different configurations. This distance is unambiguously defined for flat smooth ceilings, but for corrugated ceilings, such as corrugated metal deck ceilings found in many warehouses, the distance can be measured from either the top or the bottom of the deck. NFPA 13 states that it should be measured from the bottom if the thickness of the deck is below 75 mm and from the top if it is higher. The requirement in NFPA 13 has been adopted from the FM datasheets, but the authors have been unable to identify any background to this requirement. In this paper, the activation time of sprinkler heads at different distances below a corrugated ceiling with thickness of 125 mm was simulated using FDS 6.6.0 and compared to distances below a flat smooth ceiling. The case was based on a warehouse with 6-tier storage of Uncartoned Expanded Plastics (UEP) with a ceiling height of 11.2 m and clearance to storage of 2.6 meters. Only the activation of the first sprinkler was simulated since it was expected that the drag from droplets of previously activated sprinkler heads would thicken the ceiling jet, making the activation time of additional sprinkler less sensitive to the distance from ceiling. The results show that the corrugated ceiling has a large influence on the ceiling jet allowing sprinklers further from the ceiling to activate. In the case studied, the activation time of sprinklers below the corrugated ceiling more closely resembled those under a flat smooth ceiling when the distance below the corrugated ceiling was measured from the bottom of the deck. More simulations and experiments are however needed before any guidance on changes in sprinkler standards can be given.

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Please use this url to cite or link to this publication:
author
; and
organization
publishing date
type
Chapter in Book/Report/Conference proceeding
publication status
published
subject
keywords
CFD, corrugated ceiling, sprinkler activation, suppression
host publication
3rd European Symposium on Fire Safety Science 12–14 September 2018, Nancy, France
series title
Journal of Physics: Conference Series
volume
1107
article number
062006
edition
6
conference name
3rd European Symposium on Fire Safety Science, ESFSS 2018
conference location
Nancy, France
conference dates
2018-09-12 - 2018-09-14
external identifiers
  • scopus:85057833563
ISSN
1742-6588
DOI
10.1088/1742-6596/1107/6/062006
language
English
LU publication?
yes
id
79440af1-cf15-4ea6-b181-c6f7eb3ebd9a
date added to LUP
2018-12-19 13:52:24
date last changed
2021-08-18 04:26:21
@inproceedings{79440af1-cf15-4ea6-b181-c6f7eb3ebd9a,
  abstract     = {<p>The distance of sprinklers below ceiling is of fundamental importance since it has a great influence on activation time. Accepted distances are specified in different sprinkler standards such as NFPA 13, FM 2-0 and EN 12845 for different configurations. This distance is unambiguously defined for flat smooth ceilings, but for corrugated ceilings, such as corrugated metal deck ceilings found in many warehouses, the distance can be measured from either the top or the bottom of the deck. NFPA 13 states that it should be measured from the bottom if the thickness of the deck is below 75 mm and from the top if it is higher. The requirement in NFPA 13 has been adopted from the FM datasheets, but the authors have been unable to identify any background to this requirement. In this paper, the activation time of sprinkler heads at different distances below a corrugated ceiling with thickness of 125 mm was simulated using FDS 6.6.0 and compared to distances below a flat smooth ceiling. The case was based on a warehouse with 6-tier storage of Uncartoned Expanded Plastics (UEP) with a ceiling height of 11.2 m and clearance to storage of 2.6 meters. Only the activation of the first sprinkler was simulated since it was expected that the drag from droplets of previously activated sprinkler heads would thicken the ceiling jet, making the activation time of additional sprinkler less sensitive to the distance from ceiling. The results show that the corrugated ceiling has a large influence on the ceiling jet allowing sprinklers further from the ceiling to activate. In the case studied, the activation time of sprinklers below the corrugated ceiling more closely resembled those under a flat smooth ceiling when the distance below the corrugated ceiling was measured from the bottom of the deck. More simulations and experiments are however needed before any guidance on changes in sprinkler standards can be given.</p>},
  author       = {Runefors, Marcus and Boström, Per and Almgren, Erik},
  booktitle    = {3rd European Symposium on Fire Safety Science 12–14 September 2018, Nancy, France},
  issn         = {1742-6588},
  language     = {eng},
  series       = {Journal of Physics: Conference Series},
  title        = {Comparison of sprinkler activation times under flat and corrugated metal deck ceiling},
  url          = {http://dx.doi.org/10.1088/1742-6596/1107/6/062006},
  doi          = {10.1088/1742-6596/1107/6/062006},
  volume       = {1107},
  year         = {2018},
}