A Full-Scale Prototype Multisensor System for Damage Control and Situational Awareness

The U.S. Naval Research Laboratory has developed a real-time, remote detection system for damage control and situational awareness, called “Volume Sensor”, as part of the Advanced Volume Sensor Task, an important element of the U.S. Navy’s Office of Naval Research, Future Naval Capabilities program, Advanced Damage Countermeasures. The objective of the Advanced Volume Sensor Task was to develop an affordable detection system that could identify shipboard damage control conditions and provide real-time threat level information for damage control events (such as flaming and smoldering fires, explosions, pipe ruptures, flooding, and gas releases) while eliminating the false alarms typical of fire detection systems in industrial environments. The approach was to build a multisensor, multicriteria system from low cost commercial-off-the-shelf hardware components integrated with intelligent software and data fusion algorithms. Two multicompartment prototype Volume Sensor systems were constructed at NRL and tested with a series of simulated damage control events at the Navy’s full-scale fire test facility, the ex-USS Shadwell in Mobile Bay, AL. Results from this test series indicate that the Volume Sensor Prototypes performed as well or better than commercial video image detection and point-detection systems in critical quality metrics for fire detection while also providing additional situational awareness for flooding scenarios, fire suppression system activations, and gas release events.     

Evaluation of duct opening protection in two-hour fire walls and partitions

There is a continuing debate among fire protection specialists on the value and role of fire dampers in preventing fire spread via HVAC duct systems. It has been recognized that fire dampers are not required under all circumstances. For example, NFPA 90A,Standard for the Installation of Air Conditioning and Ventilation Systems, does not require the installation of fire dampers in ducts penetrating one-hour fire-rated walls and partitions. Additionally, there are circumstances where the closure of dampers may affect critical environmental air systems. In these situations, the value of fire dampers must be determined in terms of an overall risk assessment. It has been suggested that the role of fire dampers be considered in terms of the total building fire protection system, but a quantitative approach for such an assessment has been previously unavailable. In particular, there has been no data related to the performance of a duct system when subjected to a standard two-hour fire exposure. Gewain et al. have described an equivalency approach and full-scale fire test data for the protection of duct openings in two-hour fire-resistant walls and partitions. The objective of this paper is to review and summarize the equivalency rationale and test data and describe engineering methods available to apply an equivalency approach more generally. The approach was developed for situations where horizontal steel ventilation ducts penetrate fire-rated walls and partitions. The approach does not address smoke dampers or ducts containing combustible materials.     

Fire detection in video sequences using a generic color model

In this paper, a rule-based generic color model for flame pixel classification is proposed. The proposed algorithm uses YCbCr color space to separate the luminance from the chrominance more effectively than color spaces such as RGB or rgb. The performance of the proposed algorithm is tested on two sets of images, one of which contains fire, the other containing fire-like regions. The proposed method achieves up to 99% fire detection rate. The results are compared with two other methods in the literature and the proposed method is shown to have both a higher detection rate and a lower false alarm rate. Furthermore the proposed color model can be used for real-time fire detection in color video sequences, and we also present results for segmentation of fire in video using only the color model proposed in this paper.     

A Novel Multiscale Methodology for Simulating Tunnel Ventilation Flows During Fires

This paper applies a novel and fast modelling approach to simulate tunnel ventilation flows during fires. The complexity and high cost of full CFD models and the inaccuracies of simplistic zone or analytical models are avoided by efficiently combining mono-dimensional (1D) and CFD (3D) modelling techniques. A simple 1D network approach is used to model tunnel regions where the flow is fully developed (far field), and a detailed CFD representation is used where flow conditions require 3D resolution (near field). This multi-scale method has previously been applied to simulate tunnel ventilation systems including jet fans, vertical shafts and portals (Colella et al., Build Environ 44(12): 2357–2367, 2009) and it is applied here to include the effect of fire. Both direct and indirect coupling strategies are investigated and compared for steady state conditions. The methodology has been applied to a modern tunnel of 7 m diameter and 1.2 km in length. Different fire scenarios ranging from 10 MW to 100 MW are investigated with a variable number of operating jet fans. Comparison of cold flow cases with fire cases provides a quantification of the fire throttling effect, which is seen to be large and to reduce the flow by more than 30% for a 100 MW fire. Emphasis has been given to the discussion of the different coupling procedures and the control of the numerical error. Compared to the full CFD solution, the maximum flow field error can be reduced to less than few percents, but providing a reduction of two orders of magnitude in computational time. The much lower computational cost is of great engineering value, especially for parametric and sensitivity studies required in the design or assessment of ventilation and fire safety systems.     

Fire protection of flammable work stations in the clean room environment of a microelectronic fabrication facility

An applied engineering program is described which investigates the fire safety of combustible wet stations used within microelectronic clean room fabrication facilities. The main concern involves the impact of a wet bench fire on the clean room environment of the fabrication facility. The effectiveness of the installed fire detection and suppression systems are discussed as well as the additional steps which should be taken in order to insure early detection and suppression of fires within wet benches. Reference: Fred L. Fisher, Robert Brady Williamson, Gary L. Toms and Dennis M. Crinnion, Fire Protection of Flammable Work Stations in the Clean Room Environment of a Microelectronic Fabrication Facility,Fire Technology, Vol. 22, No. 2, May 1986, p. 148.     

Findings of the International Road Tunnel Fire Detection Research Project

Fire detection systems are essential fire protection elements for road tunnels to detect fires, activate safety systems and direct evacuation and firefighting. However, information on the performance of these systems is limited and guidelines for application of tunnel fire detection systems are not fully developed. The National Research Council of Canada and the Fire Protection Research Foundation, with support of government organizations, industries and private sector organizations, have completed a research project to investigate current fire detection technologies for road tunnel protection. The project included studies on the detection performance of current fire detection technologies with both laboratory and field fire tests combined with computer modelling studies. This paper provides an overview of the findings of the project. Fire detectors, fire scenarios and test protocols used in the test program are described. A summary of the research results of the series of full-scale fire tests conducted in a laboratory tunnel facility and in an operating road tunnel as well as of the computer modelling activities will be reported.     

Vulnerability assessment of irregular steel structures under traveling fires

This paper investigates the response of tall setback irregular steel moment resisting structures under traveling fires. A seven‐story steel regular structure (RS) is first designed for gravity and seismic loads and then it is fireproofed for a fire resistance rating (FRR) of 120 min based on the ISO834 fire. Some architectural changes are then imposed on the RS to make it a setback irregular structure (SBS). Based on the traveling fire methodology, both structures are then subjected to fire curves ranging from 1% to 100% for the fire load density (q_f) of 570 MJ/m². As in the SBS, the distribution of gravity loads is not uniform; the structural fire analyses are performed twice: when the fires start from left to right and then vice versa. The results show the FRR of the RS is minimized under the fire size of 22% with the collapse time of 87.0 min. In the SBS, when the fires start from left to right and then from right to left, the FRR is minimized under the fire size of 20% with the collapse times of 75.0 and 79.0 min, respectively. This shows that the SBS is more vulnerable toward traveling fires than the RS. In order to monitor the role of q_f in the FRRs of the structures, q_f is then reduced, and the required analyses are repeated. This process continues to where no collapse is observed under all the fire sizes. The results indicate that the RS would remain stable if the q_f is decreased to 480 MJ/m², implying that a 16% increase should be considered to the required FRR. As for the SBS, the q_f should be decreased to 440 MJ/m² to make it stable, meaning that a 25% increase should be considered to the required FRR.     

Fire performance of exterior wall insulation and finish systems

It is quite possible that variations of the systems currently available on the market may require additional or different fire testing. Successfully tested and approved systems do not present a fire hazard and should be permitted on all types of construction. Note: This paper has been unanimously adopted by EIMA as an industry position concerning fire hazard.     

Performance parameters of fire detection systems

This report is a formal, functional analysis of fire detection systems' requirements. The performance parameters of fire detection systems are given as conditional probabilities. These parameters are identified by the objective analysis of the functions of a fire detection system. It is demonstrated that using the false alarm rate to specify the malfunctioning of a thresh-old-detection system is inadequate. The principal function of fire detection systems is identified as the notification of antifire agents of the probability of an unwanted fire. The evaluation of the information provided by a detector system is central to its worth.This paper is a contribution of the National Institute of Standards and Technology and is not subject to copyright.     

Guidance for Treatment of High-Temperature Creep in Fire Resistance Analysis of Concrete Structures

Concrete structures develop high levels of transient creep strain when exposed to fire, especially when temperatures in a member exceed 500°C. This high-temperature creep strain can dominate the deformation response under severe fire scenarios and needs to be properly accounted for in the fire resistance analysis. Most of the current approaches for fire resistance calculations, including advanced analysis methods, do not consider the transient creep strain to the full extent. This paper presents design recommendations for the treatment of creep in the fire resistance analysis of concrete structures. Three design alternatives are proposed for incorporating creep in fire resistance analysis depending on the conditions encountered during fire exposure. The first solution is ‘creep-not critical’ scenario where the temperature-induced creep strain can be neglected in a structural member subjected to low stress level and experiencing low sectional temperatures. In the second scenario (‘creep-implicit’), where temperature-induced creep strain is moderate, creep can be incorporated implicitly in the analysis. Finally, in situations where creep is significant (as in the case of high stress level and sectional temperatures), it needs to be incorporated explicitly in the fire resistance analysis (‘creep-explicit’ scenario). The practicality of the proposed solution in accounting for creep in the fire resistance analysis of concrete members at different levels is demonstrated using three case studies.

     

Automatic fire detection in road traffic tunnels

Fire detection experiments in a road traffic tunnel were performed in the Runehamar test tunnel 5th–8th March 2007. The Runehamar test tunnel is a full profile road traffic tunnel, 1.65 km long, located outside Åndalsnes, Norway. The goal was to examinate smoke and heat detection systems to determinate what kind of principle best suited for detecting a fire in an early stage. The systems were tested during small Heptane pool fires, varying between 0.16 m² and 1 m², giving heat release rates from 0.2 MW to 2.4 MW accordingly, and one car fire of about 3–5 MW, and with wind conditions varying from 1.1 m s^?1 to 1.6 m s^?1. The size of the fires, were designed to be in the range from impossible to difficult to detect. The results were conclusive. Earliest detection of a car fire, fire starts inside, was by smoke detection given fixed limits (3000 μg m^?3). With open pool fires, or immediate flames, continues fibre optical heat detection systems was faster given the limits 3 °C/4 min.     

Monitoring Multiple Aspects of Fire Signatures for Discriminating Fire Detection

Numerous researchers are exploring multisensor detection as the principal means of discriminating between fire and nuisance sources. Multisensor detectors can monitor multiple aspects of a wide variety of signatures produced by flaming fires, non-flaming fires, and nuisance sources. This paper describes one program of small- and large-scale experiments that has been conducted using a prototype advanced fire detector with multiple gas sensors. An elementary analysis is applied to demonstrate that spacing guidance can be rationally developed for multiple gas sensors to detect fires of a particular threshold fire size, i.e., heat release rate. Discriminating between flaming fires, non-flaming fires, and nuisance sources could be achieved using either a threshold concentration or CO₂ rate-of-rise to identify flaming fires and a CO or CO₂ rate-of-rise for non-flaming fires. Time to detection was also compared to commercial smoke detectors, and the reductions in time were noted.     

Implementing High Reliability Fire Detection in the Residential Setting

The purpose of detecting fires early is to provide an alarm prior to when there is an environment which is deemed to be a threat to people or a building. High reliability detection is based on the supposition that it is possible to utilize a small number of sensors to ascertain unequivocally that there is a growing threat either to people or to a building and provide an estimation of the seriousness of the threat. The current generation of fire detection systems is designed to respond to smoke, heat, gaseous emission or electromagnetic radiation generated during smoldering and flaming combustion. This paper will demonstrate that these same low level signals can be utilized to achieve the goal of producing earlier detection, while improving reliability. This allows us to reduce the time to detection at the same time reducing the error rate for both false alarms as well as missing fires. Large commercial fire panels are beginning to implement such advanced algorithms for reliable fast detection; however, the focus of this work is to achieve such detection in a way that can be implemented in a lost cost, low power, EPROM which will be suitable for residential systems.     

Fire detection in computer facilities

A recent fire in a computer center in Canberra, Australia, prompted an investigation of the installed smoke detection system. The opportunity was also taken to evaluate alternate detection equipment in the actual center under operational conditions. One device tested was VESDA, a new highly sensitive smoke detector developed in Australia for clean occupancies such as computer rooms and telephone exchanges. Details of the test program and the effects of high room airflows on all forms of detectors are presented. The effectiveness of VESDA in giving very early warning of fire is demonstrated. Reference: Peter F. Johnson, Fire Detection in Computer Facilities,Fire Technology, Vol. 22, No. 1, February 1986, p. 14. Note: This paper is a modified version of a CIRL Major Report No. 251, 1984, prepared for Department of Housing and Construction, Canberra, Australia.     

Fire Detection Algorithm Combined with Image Processing and Flame Emission Spectroscopy

Fire poses a significant risk to the safety, health, and property of people around the world. However, traditional ‘‘point sensor’’ fire detection techniques for indoor buildings based on air particles, air temperatures, and smoke have a low sensitivity, long response time, and poor stability. Therefore, video-based fire detection has become a particularly efficient and important method for detecting the early signs of a fire. Due to image blur, low illumination, flame-like interference and other factors, there is a certain error rate of fire recognition using video flame recognition methods. According to our previous study of a multi-feature flame recognition algorithm, a novel flame recognition algorithm based on free radical emission spectroscopy during combustion is investigated in this paper. First, multiple features are extracted from the video images by employing our proposed processing scheme. Then, the features are post-processed by a temporal smoothing algorithm to eliminate the error recognition rate, which is caused by the similar characteristics of objects between flame-like and real flame areas. In the temporal smoothing experiments, the proposed method achieves the true positive rates of 0.965 and 0.937 for butane flames and forest fire, respectively. Additionally, the spectral signals of OH, CH, C₂ and other free radicals in the combustion objects were acquired by the spectrometer. The vibrational temperature and rotational temperature are calculated after identification of the A²Δ?→?X²Π transition of the CH (410–440 nm). The flames-like are completely rejected by the proposed method in the validation experiment. In the subsequent butane combustion experiment, the vibrational temperature of the butane was 4896 K, and the rotational temperature was 2290 K. The experimental results show that real fires can be precisely recognized and that the combustion temperature can be determined from the CH emission spectroscopy. This novel method provides a new viewpoint for fire detection and recognition.     

Fire detection using smoke and gas sensors

Fire detection systems located in aircraft cargo compartments are currently based only on smoke detectors. They generate about 200 false alarms per year for US registered aircraft. The number of false alarms is growing as more planes are outfitted with smoke detectors and air travel expands. Moreover, the survivability of an aircraft in a fire scenario depends on the early detection of the fire. A fire detection system is developed based on the simultaneous measurements of carbon monoxide, carbon dioxide, and smoke. The combination of the rates of rise of smoke and either carbon monoxide or carbon dioxide concentration provides a potential fire alarm algorithm to increase the reliability of aircraft smoke detectors, and to reduce the time to alarm. The fire detection system with the alarm algorithm detected fires that were not alarmed by smoke sensors, and alarmed in shorter times than smoke sensors operating alone.     

Combined Fire Retardant and Wood Preservative Treatments for Outdoor Wood Applications – A Review of the Literature

A collaborative Australian national project funded jointly by the Commonwealth Scientific and Industrial Research Organisation and the Forest & Wood Products Research and Development Corporation has been undertaken to develop a ‘proof of concept’ for a combined fire retardant/wood preservative treatment technology for P. radiata to satisfy the requirements of both the Australian Bushfire and Wood Preservation Standards. The focus of the work was on products that found use in exposed outdoor, above-ground applications. This paper reviews the literature currently available regarding the impregnation of wood with chemical systems that offer resistance to both fire and biodegradation and are also suitable for exterior applications. We have found that in general, researchers have chosen to utilise the dual functionality of boron compounds to achieve both fire retardancy and wood preservation. Often, such systems are applied in multi-step processes, which involve an impregnation step followed by a curing step. Because of the leaching problems associated with boron, a great deal of effort has gone into the development of systems which fix the boron into wood so that its preservation properties can be maintained throughout the useful life of the material.     

Investigation on the Performance of Fire Detection Systems for Tunnel Applications––Part 2: Full-Scale Experiments Under Longitudinal Airflow Conditions

A two-year international road tunnel fire detection research project (Phase II) was completed recently. As part of this project, a series of fire tests were conducted in a laboratory tunnel facility under minimum and longitudinal airflow conditions. In addition, fire tests were also conducted in the Carré-Viger tunnel in Montreal. This paper presents the results of the full-scale experiments conducted in the laboratory tunnel under minimum airflow conditions. The performance of nine fire detection systems representing five types of fire detection technologies was investigated using representative tunnel fire scenarios. Test results showed that the response of fire detection systems to a tunnel fire was dependent on the size, location and growth rate of the fire, the type of fuel as well as the method of detection.     

A data acquisition and recording system for fire parameters

Sufficient knowledge about the statistical properties of fire parameters especially for noise influences in ambient conditions is necessary for the design and test of both fire detectors and detection algorithms for automatic fire detection systems with improved false alarm behavior. The work described in this paper shows the measuring method as a requirement to overcome the knowledge gap.

Eight data acquisition systems and adequate measuring devices were developed, produced and calibrated, monitoring two smoke measurement principles, temperature and two control measures, relative humidity and absolute air pressure. These data acquisition systems were installed in realistic ambient conditions and false alarm relevant data were recorded.