The Science of Suppression

The 5th FIRESEAT symposium was held on Wednesday 9th November in the auditorium of the National Museum of Scotland, Edinburgh. It was attended by over 80 delegates.

Sprinklers are an increasingly widespread fire safety measure in the built environment. They are ubiquitous in warehouses and retail premises and are becoming common in residential properties and other enclosed spaces, such as subway stations and transport tunnels.

Many modern fire safety engineering solutions rely on sprinklers or other form of suppression systems, but do they work in practice, and what are the effects of these systems on fires?

The symposium explored several aspects of our understanding of suppression systems and their interactions with fires, in dwellings, storage areas and transport tunnels.

Details of all the presentations are given below. Presentational slides, accompanying papers and video of the presentations will be added in due course.


Speaker Title Slides Paper Video
Ronald L. Alpert "The Fire-Induced Ceiling Jet Revisited"
(The 3rd Philip Thomas Lecture)
PDF PDF Youtube
Yibing Xin "Fire Suppression Physics for Sprinkler Protection" PDF PDF Youtube
Andre Marshall "Knowing the fire sprinkler spray" PDF PDF Youtube
Louise Jackman "Water mist systems for building fire protection - the issues"
Videos (MP4): Office Test | 5 Min, 10 Min, 15 Min, 20 Min | Spray 5 Min
PDF PDF Youtube
Stefan Kratzmeir "Protection of Tunnels with Water Mist Systems"
Video (MP4): Fire Test
PDF PDF Youtube
Michael Delichatsios "Pool Fire Extinction by Remotely-Controlled Application of Liquid Nitrogen" PDF PDF Youtube
Elizabeth Blanchard "Modeling water spray - from laboratory scale to fire safety application" PDF PDF Youtube
Stefano Chiti "A pilot study on hypoxic air performances at the interface of fire prevention and fire suppression"
Videos (MP4): 21% Oxygen | 14% Oxygen
PDF PDF Youtube


The National Museum of Scotland has recently undergone a £47M facelift and refurbishment. It reopened to the public after a 3 year closure in July 2011.

The auditorium in the museum, where the first FIRESEAT symposium was held in 2007, has been completely refurbished and is now a state of the art presentation space, with its own dedicated entrance lobby and exhibition area.


Ronald L. Alpert

"The Fire-Induced Ceiling Jet Revisited"
(The 3rd Philip Thomas Lecture)

Data from 1972 on near-maximum gas velocity and excess temperature in the ceiling jet induced by large-scale fires that were used to obtain well-known ceiling-jet correlations have been re-examined in light of knowledge on the virtual plume origin and the convective component of the fire heat release rate. The new correlations developed from this re-examination are compared with the original correlations that were based on actual ceiling height above the top fuel surface and total rate of fire heat release, instead of being based on the difference between the ceiling height and the virtual origin height above the flame base and on the convective heat release rate. A full description of these data is provided as well as a description of the methods used to revise the correlation. This ceiling-jet analysis, useful for the prediction of detection and activation times, is followed by a discussion of how the calculation of the interaction of fire-induced flows with droplet sprays is needed to predict droplet penetration to burning fuel surfaces as well as the total number of automatic spray devices activated during a fire. Finally, there is a brief discussion of how an intermediate-scale configuration of combustible surfaces can be used to investigate the flammability of materials and minimum required water flux to control fire spread.

Yibing Xin

"Fire Suppression Physics for Sprinkler Protection"

Fire protection using sprinklers is one of the most cost-effective and reliable technologies available for fire safety and property protection design. Given the complexity associated with sprinkler protection, fire protection requirements and standards have mostly been developed to date by conducting large-scale tests that are costly and often difficult to generalize. Numerical modeling has long been pursued as a cost-effective method that can supplement large-scale testing and give valuable physical insights when interpreting test data. Therefore, there is a strong and continued interest in the fire community on the development of predictive fire modeling capabilities of large-scale fires with sprinkler protection through the use of new-generation computational fluid dynamics (CFD) tools. The key issue in achieving this objective is to understand and model the most important physical phenomena associated with sprinkler protection. To address this issue, FM Global initiated sprinkler technology program, focusing on the study of fire suppression physics for sprinkler protection. The present paper discusses exploratory work in the sprinkler technology program, including measurements of sprinkler spray properties and spray penetration, water absorption by porous fuels, surface and corner water flows, water transport in rack storage, and water evaporation and fire suppression experiments in single-wall and parallel panel configurations. This paper will also introduce ongoing experimental studies and future plans to guide model development and validate modeling results, with the ultimate goal of simulating sprinkler protection of commodities in the real world.

Andre Marshall

"Knowing the fire sprinkler spray"

Sprinklers generate complex large scale sprays using an elegant and efficient design concept. These devices establish thin sheets via jet impact onto a deflector. These inherently unstable sheets fragment readily to form drops (~ 0.1 x jet diameter). Despite their conceptual simplicity, sprinklers produce highly three dimensional stochastic sprays whose characteristics are poorly understood. Only the most basic connections have been made between sprinkler design details and their resulting sprays. In fact, the understanding of sprinkler spray formation has not progressed beyond the conceptual stage despite over 100 years of operational experience with these devices in concert with relentless testing and measurement of the sprays that they produce. Sprinkler design innovation is slow, in part, because spray characterization has focused primarily on delivery (i.e. readily measured farfield performance) with very little attention given to generation (i.e. intractable nearfield details). Advanced measurement concepts and techniques are currently being applied to the previously intractable nearfield providing the insight (into sprinkler discharge characteristics) required to improve not only sprinkler design but also engineering practices. A number of modern measurement techniques and modeling tools are presented to illuminate the path toward development of next generation water-based fire suppression systems.

Stefan Kratzmeir

"Protection of Tunnels with Water Mist Systems"

Water Mist Systems are more and more used for the protection of tunnels. The development started with the European research project UPTUN and was continued with the SOLIT and SOLIT2 project.
The presentation will give an overview of fixed firefighting systems (FFFS) based on water mist technology in tunnels. Special focus will be given to the real scale fire test series within the SOLIT and SOLIT2 project and the effect of water mist systems on fire in tunnels. Furthermore on the example of the New Tyne Crossing (Newcastle) it will be showed, how test results of a full scale fire test are transferred into a real project.

Michael Delichatsios

"Pool Fire Extinction by Remotely-Controlled Application of Liquid Nitrogen" with Yiannis Levendis

This presentation is an extension of previous work on extinction by liquid nitrogen presents a technique for effective remotely-controlled application of the cryogen to fires. The cryogen is carried to an event in insulated and vented containers in trucks; there from it is pumped to the fire through a vacuum-insulated hose, fitted with cryogenic valves. Application of the cryogen from a distance, by spraying through a nozzle, proved challenging, as the ensuing liquid ligaments rapidly vaporize along their trajectory paths. To the contrary, use of a remotely-guided unmanned robotic vehicle to carry the hose to the fire and discharge the cryogen therein much more effective. Upon contact with a pyrolyzing/burning surface, abrupt vaporization of the cryogen generated cold vapors, which spread by gravity and blanketed the burning area. The pyrolyzing gases were inerted, the surface cooled and its pyrolysis rate reduced, air separated from the fuel and, hence, the fire extinguished. To demonstrate this technique, experiments were conducted with pool fires of isopropanol. A small robotic vehicle was designed and constructed in-house to deliver small quantities of the cryogen extinguished to small-scale pool fires, arranged in different patterns. Fire extinction in these feasibility tests was fast and effective.

Elizabeth Blanchard

"Modeling water spray - from laboratory scale to fire safety application"

Water-based fixed fire fighting systems (WFFFS) are more and more considered as a way to improve fire safety in tunnels via controlling fire spread and the heat release. Before any WFFFS design acceptation, French authorities require real scale fire tests campaign to assess its performance. Into this context, computational codes could be interesting, either for helping defining test procedure, limiting the number of tests or helping the experimental measurements understanding. Our work on water mist consists in validating the existing code Fire Dynamics Simulator (FDS, NIST), proposing few modifications for the water spray modeling and establishing its use conditions. It deals with validation tests from the laboratory scale (about radiation attenuation and droplet evaporation) up to the model tunnel scale (1/3).

Stefano Chiti

"A pilot study on hypoxic air performances at the interface of fire prevention and fire suppression"

Even fire suppression is not acceptable in applications where a fire, even if suppressed quickly, would cause unacceptable damages. In these cases fire can be prevented rather than suppressed using hypoxic air. Due to limited research on fire prevention techniques pilot studies have been made to establish the facts, available test methods and performances of present options as well as identifying the less researched areas. Hypoxic air technology is based on a continuous reduction of the oxygen in the protected enclosure in order to limit the oxygen availability to the combustion process: typically a small amount of the oxygen in the air is replaced with nitrogen. The effect of low oxygen concentrations on the combustion process is investigated by a literature survey of the existing pertinent sources. An overview of ignition property test methods is made and a recent test method to assess the performance of a hypoxic air fire prevention system is discussed. The borderline performances of hypoxic air systems have been explored by means of a test series which include reference tests of known ignitable specimens as well as new materials, configurations and applications.


Ronald L. Alpert

Dr. Ronald L. Alpert, FSFPE, received his undergraduate and graduate education at the Massachusetts Institute of Technology, where he majored in Mechanical Engineering. He began his 34-year career at FM Global by investigating experimentally and theoretically the fire-induced ceiling-jet and its role in fire detection. Subsequently, Dr. Alpert conducted investigations of the flashover phenomenon, scale-modeling of fire propagation/convection and contributed to the prediction of fire sprinkler performance through the development of numerical simulation techniques. His work on a deterministic model of fire propagation in a parallel panel configuration was the subject of an invited talk at the 7th International Symposium on Fire Safety Science.

Dr. Alpert retired in 2004 as principal research scientist and assistant vice president from FM Global Research, where he managed the Flammability Technology Research Program. During retirement, he has been a consultant on fire protection science and an active participant in the ISO technical committee on Fire Safety and its subcommittee on Fire Safety Engineering, leading the U.S. delegation on FSE and chairing the working group on Calculation Methods. He has authored/co-authored more than 20 papers in refereed journals, authored a chapter in the SFPE Handbook of Fire Protection Engineering, 3rd and 4th Editions and is editor of the Journal of Fire Protection Engineering, the official journal of the Society of Fire Protection Engineers.

Yibing Xin

Dr. Yibing Xin is a senior research specialist at FM Global, and is currently the program manager of sprinkler technology program and the technical team leader of water suppression group in research division. He obtained his Ph.D. degree in mechanical engineering from Purdue University in 2002 and joined FM Global in 2003. Since then, Dr. Xin has been working on both experimental and numerical studies of fire protection, with special interests in sprinkler-based fire suppression, commodity classification, oxygen reduction system and numerical fire modeling. Dr. Xin also represents FM Global on NFPA smoke management committee and SFPE task group developing fire modeling guidelines.

Elizabeth Blanchard

Elizabeth Blanchard is a PhD student at the French governmental building research laboratory (CSTB) and at the French National Centre for Scientific Research (CNRS, LEMTA). She is a civil engineer and has an MS in Mathematical modeling and fluid mechanics. Since 2008, she has been studying water spray modeling from the laboratory scale to the fire safety application.

Science of Supression
Science of Supression
Edinburgh National Museum
Edinburgh National Museum
Ronald Alpert
Ronald Alpert