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W.K. Chow

The Hong Kong Polytechnic University, Department of Building Environment and Energy Engineering, Emeritus Professor (Architectural Science and Fire Engineering)

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W.K. Chow was appointed as Justice of the Peace in 2013, and elected as Fellow of the Hong Kong Academy of Engineering Sciences in 2012. He graduated from the University of Hong Kong with a first class honours BSc degree in 1977 and a PhD degree in Theoretical Physics in 1983

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Papers by W.K. Chow

Application of the Zone Model FIRST on the Development of Smoke Layer and Evaluation of Smoke Extraction Design for Atria in Hong Kong

Journal of Fire Sciences, 1993

Whether a smoke extraction system has to be installed for an atrium building in Hong Kong is dete... more Whether a smoke extraction system has to be installed for an atrium building in Hong Kong is determined by its volume. This article reports an evaluation of this regulation using the zone model FIRST developed at the Building and Fire Research Laboratory, NIST, U.S.A. A survey of the geometri cal configurations of the local atria is made. The general shapes of the atria are classified into three types: 1, 2 and 3, with types 2 and 3 further divided into three sub-types: A, B and C. Smoke filling in those atria is simulated by the model FIRST with the volumes of the atrium space varied from 2500 m3 to 35,000 m 3. It is illustrated that specifying only the volume of the atrium space is not good enough to determine whether a smoke extraction system has to be installed. The geometrical configuration is recommended to be included as well. A time constant is defined for the atrium with a certain design fire.

Six Dimension and the Generalized Fermat's Theorem

by W.K. Chow and Peter C.W. Fung

Fermat's Last Theorem is generalized to Six Dimension by including Temperature as an imaginary co... more Fermat's Last Theorem is generalized to Six Dimension by including Temperature as an imaginary component of time and Gravity becomes an imaginary component of energy. Temperature dimension is classical. While the imaginary energy is responsible for gravitons. When time is absent, or is a fixed value, the remaining 5D without time domains represent the enclosing boundary domain to the 6D manifold, with gravity due to the duality between energy and mass, and represent Dark Matter domains. Any mass that might exist inside behaves like Tachyons, with imaginary energy. Due to the imaginary energy, Tachyon-anti-Tachyon if present is in pairs. And they will annihilate each other and produce a static gravity potential.

A brief review on flame spread over lignocellulosic materials

Journal of Applied Fire Science, 2012

Flammability is an important factor in the selection of fire-safe materials. Flame spread is a ke... more Flammability is an important factor in the selection of fire-safe materials. Flame spread is a key component to assess the flammability of materials. It is crucial in determining the fire size, the safe evacuation time and the effectiveness of fire protection measures. Lignocellulosic materials constitute a substantial fraction to the fuel load in building fires. Numerous studies on their flame spread were reported in the literature. A brief review on standard tests and a mathematical model of flame spread over lignocellulosic materials will be reported in this paper. Different standard tests were developed to assess flame spread over materials with quantified data. Materials that passed safety testing may not be safe in a real fire. A better understanding of the mechanism based on flame spread test data is useful to assess the fire safety of materials. Many analytical models were reported in the literature, but their application is quite limited. A more detailed mathematical model should be developed as a predictive tool for selecting fire safe materials.

Experimental Study on Blocking Fire and Smoke by Water Curtain

Journal of Applied Fire Science, 2008

Fire resisting constructions can be substituted by drencher system for big construction projects ... more Fire resisting constructions can be substituted by drencher system for big construction projects in the Far East. The discharged water curtain is useful in blocking thermal radiation from the fire compartment to the neighbouring area for normal fires. There are concerns on whether smoke spreading can be blocked. Performance of water curtain on blocking heat and smoke was evaluated experimentally with a two-room structure. There would be different blocking effects on smoke emitted from burning different fuels. Better smoke obstruction of water curtain was observed for smoke with larger particles. More smoke can be blocked by discharging several water layers. Smoke filling time in the protected room can be extended upon discharging a water curtain. This is very useful for allowing longer time to evacuate occupants.

Evacuation Studies for Tall Office Buildings in Hong Kong

Journal of Applied Fire Science, 2006

The majority of the labour force in Hong Kong are now working in offices. Fire safety in such non... more The majority of the labour force in Hong Kong are now working in offices. Fire safety in such non-industrial workplaces should be watched. The most important part is to evacuate the occupants inside. The total evacuation time in office buildings should be kept at a lower value. In this paper, evacuation in the offices of tall buildings will be studied. The regulations for designing escape routes in Hong Kong, USA and UK are reviewed first. The codes and associated parameters in the three different places are compared. Provisions of means of escape in selected offices are then studied. A sample of 10 offices for small and medium enterprises was selected for analysis. The minimum total evacuation time was calculated by empirical flow models commonly used in performance-based design. Results on the evacuation time available for the occupants are used to justify the evacuation design in following the codes. Design on means of escape and the required evacuation time are discussed. It is observed that even when the code specifications are followed, the minimum total evacuation time might be longer than the limit specified in the code. Points to note for improving the evacuation codes are recommended.

Smoke Control by Air Curtain for Spaces Adjacent to Atria

Journal of Environmental Systems, 1999

Smoke control design by using air curtains in spaces adjacent to "open-design" atria was evaluate... more Smoke control design by using air curtains in spaces adjacent to "open-design" atria was evaluated using Computational Fluid Dynamics (CFD). The design mechanical installs systems for discharging air vertically downward (commonly known as an air curtain) to isolate spaces adjacent to the atrium for preventing smoke spreading to those areas. Performance of the design was evaluated by carrying out two sets of CFD simulations with heat release rates of the fire of 1 MW and 5 MW. An atrium of length 10 m, width 10 m and height 10 m with an adjacent area 6 m above the atrium floor was considered. Air speed of 1 ms-1 to 10 ms-1 discharged vertically downward, corresponding to volumetric flow rates of thirty-six air changes per hour to 360 air changes per hour of atrium volume space were studied.

Evacuation in an Underground Auditorium

Evacuation is a key issue in performance-based design for fire safety provisions. Many empirical ... more Evacuation is a key issue in performance-based design for fire safety provisions. Many empirical expressions on evacuation are commonly used with justification from field studies. However, there are doubts in using those equations for moving upstairs. In this paper, such empirical equations were applied to estimate the evacuation times for moving up an underground auditorium. Results are compared with field study. It is observed that those simple empirical equations are applicable to estimate the evacuation time for moving upstairs.

A Retrospective Survey on Elevator Evacuation of Supertall Building Under Fires

Many supertall buildings up to 500 m are constructed in the Far East. Big fires in such tall buil... more Many supertall buildings up to 500 m are constructed in the Far East. Big fires in such tall buildings during office hours are a nightmare to firemen. Lots of combustibles might be stored in crowded offices with glass facades. Big fires in tall buildings have been observed many times all over the world. Evacuation is identified as the key problem. Full evacuation is impossible for supertall buildings, taking over two hours even in a normal fire drill with good orders. Refuge floors and staged evacuation might be a solution. However, there are queries on whether refuge floors are safe under big post-flashover fires after the World Trade Center tragedy. Elevators are proposed for selective use in the case of fire for accelerating the evacuation process. Studies on elevator evacuation for tall buildings of normal height started over twenty years ago in North America. Results on smoke movement and its management in tall buildings of normal height; human behaviour and orderly evacuation; evacuation times modelling; integration with refuge evacuation; and water damage were reported. None of those works related specifically to supertall buildings under big fires. In fact, the use of elevators is included in the evacuation strategy for several supertall buildings in Hong Kong. The elevator systems, however, are not demonstrated to be safe in a fire, leading to deep concern from local fire authority. There is an urgent need to evaluate performance of such existing elevator systems for emergency evacuation in supertall buildings. Active fire protection systems should be upgraded if necessary. In this paper, concerns of elevator evacuation are summarized. Points of consideration in designing safe elevator systems in supertall buildings under big fires will be discussed with reference to the literature works.

Combining heat release rates of combustibles

Journal of Applied Fire Science, 2007

Many combustibles will be put together in a compartment. If there is a fire, not just one item wi... more Many combustibles will be put together in a compartment. If there is a fire, not just one item will burn. In fire hazard assessment, the resultant heat release rate of burning several items, instead of just one single object has to be known. The principle of superposition is commonly used for combining the heat release rate curves of burning several items. This will be further investigated by carrying out full-scale burning tests. Two combustible items, a polyurethane foam sofa and a timber partition board, were selected. Different combinations were burnt in a full-scale burning facility in the remote area of Northern China. It is found that resultant effects of the transient heat release rate curves of burning two items cannot be obtained simply by adding the individual curves together. The calculated peak heat release rate might be very different from the one determined experimentally if the time to ignition was not considered carefully. However, the curves on the transient total amount of heat released would be similar. Results suggested that the heat transfer between the two items should be considered. In testing single items, including thermal radiation heat fluxes would allow flexibility to combine heat release rate curves of different combustibles together.

Review on emergency evacuation time estimation for performance-based fire safety design

Journal of Applied Fire Science, 2006

Fire safety provisions have to be determined through performance-based design in many projects. T... more Fire safety provisions have to be determined through performance-based design in many projects. There is a need for quick estimation of evacuation time for scenario analysis in hazard assessment. The key equations on estimating evacuation time have to be better understood. An updated review on emergency evacuation will be presented in this paper. Review started from the earlier works based on hydraulic flow models. Three key parameters on crowd density, movement speed and flow rate are outlined. Design values recommended in those calculation procedures are summarized in a table and several graphs for horizontal movement, up and down stairs.

Building Fire Codes and Performance-Based Design in China: Mainland and Hong Kong

Journal of Applied Fire Science, 2005

Many big construction projects are developed in China including the Mainland and the Hong Kong Sp... more Many big construction projects are developed in China including the Mainland and the Hong Kong Special Administrative Region (formerly Hong Kong before 1 July 1997). Consequent to several big fires with serious consequences, fire safety provisions will be assessed vigorously. As there are more overseas involvements in larger-scale construction projects in these two areas, it is interesting to compare the assessment and approval procedures of fire safety designs in the two areas. In this paper, the building fire codes in Mainland and Hong Kong will be briefly reviewed first. Application procedure for new project is outlined. These codes are basically prescriptive, buildings with new architectural features might have difficulties in complying with the specifications. Implementation of performance-based design is also discussed. Problems encountered are outlined with improvements suggested.

A note on applying the displacement method in assessing fire hazard of glass systems

Journal of Applied Fire Science, 2005

Planar thermoelasticity problems have to be solved in assessing the fire hazard of glass systems.... more Planar thermoelasticity problems have to be solved in assessing the fire hazard of glass systems. The displacement method was proposed to solve such problems. The two-dimensional heat transfer equation will be solved by the Green's theorem. A potential function was derived to give the displacement, strain and stress. Similar to the Airy stress function, the displacement function used in this paper will also satisfy the set of equations concerned. Behaviour of thin glass panels in a fire is proposed to be studied by this displacement method in calculating the temperature distribution.

Survey on geometrical aspect ratios of supertall buildings

Journal of Applied Fire Science, 2005

Many supertall buildings are built in the Far East. Since prescriptive fire codes had not yet bee... more Many supertall buildings are built in the Far East. Since prescriptive fire codes had not yet been demonstrated to cover such tall buildings, performance-based designs were commonly adopted. However, fire safety objectives, scenario identification, hazard assessment and acceptance criteria were not worked out through in-depth scientific research. Fire safety is therefore a concern and further investigational works are necessary. Before working out a detailed investigational plan, existing supertall buildings have to be surveyed to understand the possible problems. The first step is to survey their aspect ratios and results are presented in this paper. A survey on 54 supertall buildings was carried out with aspect ratios calculated. Range and distribution of the aspect ratios of supertall buildings are studied. Correlations of different aspect ratios with heights are proposed. Supertall buildings in two countries, China and USA were taken out to study in more detail. The average aspect ratios are calculated and compared.

Survey on Fire Risk Factors for Offices of Small and Medium Enterprises

Journal of Applied Fire Science, 2005

Fire safety for offices of small and medium enterprises (SME) established in Hong Kong is a conce... more Fire safety for offices of small and medium enterprises (SME) established in Hong Kong is a concern. The possible fire risks should be studied before determining the fire safety provisions. A long-term research project was supported and the first step is to survey on the fire risk factors in those offices. The two key factors on fire load density and occupant load factor were studied in 25 SME offices. This sample covered a large variety of businesses in engineering, advertising and trading firms. The fire load densities for the samples were found to be from 316 to 1585 MJm-2 , giving a mean of 911 MJm-2. Both the fixed and movable fire loads were analyzed. On the occupant load factor, values were lying between 4 m 2 /person to 13.33 m 2 /person, giving a mean of 7.7 m 2 /person. These two factors are important in determining the fire safety provisions in offices, both on hardware passive constructions and active fire systems. From the results, appropriate fire safety management can be worked out.

Smoke toxicity assessment of burning video compact disc boxes by a cone calorimeter

Journal of Applied Fire Science, 2002

Video compact discs (VCD) are usually stored in plastic boxes for protection. Smoke toxicity of b... more Video compact discs (VCD) are usually stored in plastic boxes for protection. Smoke toxicity of burning VCD boxes in a cone calorimeter will be assessed in this paper. Samples of the materials commonly available in the market are burnt under different radiant heat fluxes from 10 kWm-2 to 70 kWm-2. Concentrations of carbon dioxide and carbon monoxide emitted are measured. The effects to human beings will be assessed based on the fractional exposure dose (FED) measured in the cone calorimeter. Smoke toxicity effects in real-scale fires will be estimated by some correlations. It is further confirmed that very different smoke toxicity effects will be resulted from different scenarios of burning the VCD boxes.

Assessing construction elements with lower fire resistance rating under big fire

Journal of Applied Fire Science, 2005

There are proposals on using fire resisting construction and structural elements with fire resist... more There are proposals on using fire resisting construction and structural elements with fire resistance ratings lower than the values specified in the fire codes. The equal temperature-time exposure concept or t-equivalent rule is commonly applied to support the argument. However, there are concerns in applying such approach for bigger fires as the radiative heat flux acting on the construction element is not included. Fire hazard assessment on that should be watched. This is a short note on discussing possible problems associated with fire resisting construction with lower ratings. Full-scale burning tests with bigger fires are suggested to support the argument and to demonstrate that the equal temperature-time concept would work as expected.

Preliminary Full-Scale Burning Tests of Electric Cables

Journal of Applied Fire Science, 2004

Full-scale burning tests on PVC electric cables at post-flashover stage were carried out. Real-sc... more Full-scale burning tests on PVC electric cables at post-flashover stage were carried out. Real-scale room fires were considered and the heat release rates were measured. The results on the total heat release were compared with those measured from a cone calorimeter with different heat fluxes. Language: en

Decay of Buoyant Smoke Layer Temperature Along the Longitudinal Direction in Tunnel Fires

Journal of Applied Fire Science, 2004

A simple model was reported to predict the longitudinal distribution of temperature rise for the ... more A simple model was reported to predict the longitudinal distribution of temperature rise for the smoke layer along a tunnel. The longitudinal decay of excess smoke layer temperature in dimensionless form was studied by including convective and radiative heat transfer to the boundary. An expression was derived to relate to the dimensions of the cross-section of the tunnel, the depth and the velocity of the smoke layer to the temperature. A series of full-scale tests was conducted in three vehicular tunnels to verify the model. There, temperature field and smoke layer traveling velocity were measured downstream the fire source. The decay factors for longitudinal smoke layer excess temperature distributions were predicted from the model based on the smoke layer velocities and the dimensions of the vehicular tunnel. Results are then compared with those deduced directly from the measured temperature data. Good agreement was achieved. Language: en

Evacuation Studies for Tall Office Buildings in Hong Kong

Journal of Applied Fire Science, 2006

Combining Bromofluoropropene with Water Mist for Suppressing Deep Seated Wood Crib Fires

Fire Safety Science, 2014

Application of 2-bromo-3,3,3-trifluoropropene (BTP) with water mist in suppressing deep seated wo... more Application of 2-bromo-3,3,3-trifluoropropene (BTP) with water mist in suppressing deep seated wood crib fires was reported in this paper. Performance of the combination of the two clean fire suppressants was examined by laboratory scale experiments and compared with water mist and BTP used alone. Results showed that coupling of water mist with BTP could extinguish the wood crib fires with high efficiency, in which BTP discharged first could fast extinguish the flame, and the following water mist could cool the wood surface and stop glowing combustion. As a result, a complete fire extinguishment without re-strike was achieved in short time. Furthermore, hydrogen fluoride (HF) acid gas produced in the suppression process was acceptable for the use of water mist in conjunction with BTP.

Application of the Zone Model FIRST on the Development of Smoke Layer and Evaluation of Smoke Extraction Design for Atria in Hong Kong

Journal of Fire Sciences, 1993

Whether a smoke extraction system has to be installed for an atrium building in Hong Kong is dete... more Whether a smoke extraction system has to be installed for an atrium building in Hong Kong is determined by its volume. This article reports an evaluation of this regulation using the zone model FIRST developed at the Building and Fire Research Laboratory, NIST, U.S.A. A survey of the geometri cal configurations of the local atria is made. The general shapes of the atria are classified into three types: 1, 2 and 3, with types 2 and 3 further divided into three sub-types: A, B and C. Smoke filling in those atria is simulated by the model FIRST with the volumes of the atrium space varied from 2500 m3 to 35,000 m 3. It is illustrated that specifying only the volume of the atrium space is not good enough to determine whether a smoke extraction system has to be installed. The geometrical configuration is recommended to be included as well. A time constant is defined for the atrium with a certain design fire.

Six Dimension and the Generalized Fermat's Theorem

by W.K. Chow and Peter C.W. Fung

Fermat's Last Theorem is generalized to Six Dimension by including Temperature as an imaginary co... more Fermat's Last Theorem is generalized to Six Dimension by including Temperature as an imaginary component of time and Gravity becomes an imaginary component of energy. Temperature dimension is classical. While the imaginary energy is responsible for gravitons. When time is absent, or is a fixed value, the remaining 5D without time domains represent the enclosing boundary domain to the 6D manifold, with gravity due to the duality between energy and mass, and represent Dark Matter domains. Any mass that might exist inside behaves like Tachyons, with imaginary energy. Due to the imaginary energy, Tachyon-anti-Tachyon if present is in pairs. And they will annihilate each other and produce a static gravity potential.

A brief review on flame spread over lignocellulosic materials

Journal of Applied Fire Science, 2012

Flammability is an important factor in the selection of fire-safe materials. Flame spread is a ke... more Flammability is an important factor in the selection of fire-safe materials. Flame spread is a key component to assess the flammability of materials. It is crucial in determining the fire size, the safe evacuation time and the effectiveness of fire protection measures. Lignocellulosic materials constitute a substantial fraction to the fuel load in building fires. Numerous studies on their flame spread were reported in the literature. A brief review on standard tests and a mathematical model of flame spread over lignocellulosic materials will be reported in this paper. Different standard tests were developed to assess flame spread over materials with quantified data. Materials that passed safety testing may not be safe in a real fire. A better understanding of the mechanism based on flame spread test data is useful to assess the fire safety of materials. Many analytical models were reported in the literature, but their application is quite limited. A more detailed mathematical model should be developed as a predictive tool for selecting fire safe materials.

Experimental Study on Blocking Fire and Smoke by Water Curtain

Journal of Applied Fire Science, 2008

Fire resisting constructions can be substituted by drencher system for big construction projects ... more Fire resisting constructions can be substituted by drencher system for big construction projects in the Far East. The discharged water curtain is useful in blocking thermal radiation from the fire compartment to the neighbouring area for normal fires. There are concerns on whether smoke spreading can be blocked. Performance of water curtain on blocking heat and smoke was evaluated experimentally with a two-room structure. There would be different blocking effects on smoke emitted from burning different fuels. Better smoke obstruction of water curtain was observed for smoke with larger particles. More smoke can be blocked by discharging several water layers. Smoke filling time in the protected room can be extended upon discharging a water curtain. This is very useful for allowing longer time to evacuate occupants.

Evacuation Studies for Tall Office Buildings in Hong Kong

Journal of Applied Fire Science, 2006

The majority of the labour force in Hong Kong are now working in offices. Fire safety in such non... more The majority of the labour force in Hong Kong are now working in offices. Fire safety in such non-industrial workplaces should be watched. The most important part is to evacuate the occupants inside. The total evacuation time in office buildings should be kept at a lower value. In this paper, evacuation in the offices of tall buildings will be studied. The regulations for designing escape routes in Hong Kong, USA and UK are reviewed first. The codes and associated parameters in the three different places are compared. Provisions of means of escape in selected offices are then studied. A sample of 10 offices for small and medium enterprises was selected for analysis. The minimum total evacuation time was calculated by empirical flow models commonly used in performance-based design. Results on the evacuation time available for the occupants are used to justify the evacuation design in following the codes. Design on means of escape and the required evacuation time are discussed. It is observed that even when the code specifications are followed, the minimum total evacuation time might be longer than the limit specified in the code. Points to note for improving the evacuation codes are recommended.

Smoke Control by Air Curtain for Spaces Adjacent to Atria

Journal of Environmental Systems, 1999

Smoke control design by using air curtains in spaces adjacent to "open-design" atria was evaluate... more Smoke control design by using air curtains in spaces adjacent to "open-design" atria was evaluated using Computational Fluid Dynamics (CFD). The design mechanical installs systems for discharging air vertically downward (commonly known as an air curtain) to isolate spaces adjacent to the atrium for preventing smoke spreading to those areas. Performance of the design was evaluated by carrying out two sets of CFD simulations with heat release rates of the fire of 1 MW and 5 MW. An atrium of length 10 m, width 10 m and height 10 m with an adjacent area 6 m above the atrium floor was considered. Air speed of 1 ms-1 to 10 ms-1 discharged vertically downward, corresponding to volumetric flow rates of thirty-six air changes per hour to 360 air changes per hour of atrium volume space were studied.

Evacuation in an Underground Auditorium

Evacuation is a key issue in performance-based design for fire safety provisions. Many empirical ... more Evacuation is a key issue in performance-based design for fire safety provisions. Many empirical expressions on evacuation are commonly used with justification from field studies. However, there are doubts in using those equations for moving upstairs. In this paper, such empirical equations were applied to estimate the evacuation times for moving up an underground auditorium. Results are compared with field study. It is observed that those simple empirical equations are applicable to estimate the evacuation time for moving upstairs.

A Retrospective Survey on Elevator Evacuation of Supertall Building Under Fires

Many supertall buildings up to 500 m are constructed in the Far East. Big fires in such tall buil... more Many supertall buildings up to 500 m are constructed in the Far East. Big fires in such tall buildings during office hours are a nightmare to firemen. Lots of combustibles might be stored in crowded offices with glass facades. Big fires in tall buildings have been observed many times all over the world. Evacuation is identified as the key problem. Full evacuation is impossible for supertall buildings, taking over two hours even in a normal fire drill with good orders. Refuge floors and staged evacuation might be a solution. However, there are queries on whether refuge floors are safe under big post-flashover fires after the World Trade Center tragedy. Elevators are proposed for selective use in the case of fire for accelerating the evacuation process. Studies on elevator evacuation for tall buildings of normal height started over twenty years ago in North America. Results on smoke movement and its management in tall buildings of normal height; human behaviour and orderly evacuation; evacuation times modelling; integration with refuge evacuation; and water damage were reported. None of those works related specifically to supertall buildings under big fires. In fact, the use of elevators is included in the evacuation strategy for several supertall buildings in Hong Kong. The elevator systems, however, are not demonstrated to be safe in a fire, leading to deep concern from local fire authority. There is an urgent need to evaluate performance of such existing elevator systems for emergency evacuation in supertall buildings. Active fire protection systems should be upgraded if necessary. In this paper, concerns of elevator evacuation are summarized. Points of consideration in designing safe elevator systems in supertall buildings under big fires will be discussed with reference to the literature works.

Combining heat release rates of combustibles

Journal of Applied Fire Science, 2007

Many combustibles will be put together in a compartment. If there is a fire, not just one item wi... more Many combustibles will be put together in a compartment. If there is a fire, not just one item will burn. In fire hazard assessment, the resultant heat release rate of burning several items, instead of just one single object has to be known. The principle of superposition is commonly used for combining the heat release rate curves of burning several items. This will be further investigated by carrying out full-scale burning tests. Two combustible items, a polyurethane foam sofa and a timber partition board, were selected. Different combinations were burnt in a full-scale burning facility in the remote area of Northern China. It is found that resultant effects of the transient heat release rate curves of burning two items cannot be obtained simply by adding the individual curves together. The calculated peak heat release rate might be very different from the one determined experimentally if the time to ignition was not considered carefully. However, the curves on the transient total amount of heat released would be similar. Results suggested that the heat transfer between the two items should be considered. In testing single items, including thermal radiation heat fluxes would allow flexibility to combine heat release rate curves of different combustibles together.

Review on emergency evacuation time estimation for performance-based fire safety design

Journal of Applied Fire Science, 2006

Fire safety provisions have to be determined through performance-based design in many projects. T... more Fire safety provisions have to be determined through performance-based design in many projects. There is a need for quick estimation of evacuation time for scenario analysis in hazard assessment. The key equations on estimating evacuation time have to be better understood. An updated review on emergency evacuation will be presented in this paper. Review started from the earlier works based on hydraulic flow models. Three key parameters on crowd density, movement speed and flow rate are outlined. Design values recommended in those calculation procedures are summarized in a table and several graphs for horizontal movement, up and down stairs.

Building Fire Codes and Performance-Based Design in China: Mainland and Hong Kong

Journal of Applied Fire Science, 2005

Many big construction projects are developed in China including the Mainland and the Hong Kong Sp... more Many big construction projects are developed in China including the Mainland and the Hong Kong Special Administrative Region (formerly Hong Kong before 1 July 1997). Consequent to several big fires with serious consequences, fire safety provisions will be assessed vigorously. As there are more overseas involvements in larger-scale construction projects in these two areas, it is interesting to compare the assessment and approval procedures of fire safety designs in the two areas. In this paper, the building fire codes in Mainland and Hong Kong will be briefly reviewed first. Application procedure for new project is outlined. These codes are basically prescriptive, buildings with new architectural features might have difficulties in complying with the specifications. Implementation of performance-based design is also discussed. Problems encountered are outlined with improvements suggested.

A note on applying the displacement method in assessing fire hazard of glass systems

Journal of Applied Fire Science, 2005

Planar thermoelasticity problems have to be solved in assessing the fire hazard of glass systems.... more Planar thermoelasticity problems have to be solved in assessing the fire hazard of glass systems. The displacement method was proposed to solve such problems. The two-dimensional heat transfer equation will be solved by the Green's theorem. A potential function was derived to give the displacement, strain and stress. Similar to the Airy stress function, the displacement function used in this paper will also satisfy the set of equations concerned. Behaviour of thin glass panels in a fire is proposed to be studied by this displacement method in calculating the temperature distribution.

Survey on geometrical aspect ratios of supertall buildings

Journal of Applied Fire Science, 2005

Many supertall buildings are built in the Far East. Since prescriptive fire codes had not yet bee... more Many supertall buildings are built in the Far East. Since prescriptive fire codes had not yet been demonstrated to cover such tall buildings, performance-based designs were commonly adopted. However, fire safety objectives, scenario identification, hazard assessment and acceptance criteria were not worked out through in-depth scientific research. Fire safety is therefore a concern and further investigational works are necessary. Before working out a detailed investigational plan, existing supertall buildings have to be surveyed to understand the possible problems. The first step is to survey their aspect ratios and results are presented in this paper. A survey on 54 supertall buildings was carried out with aspect ratios calculated. Range and distribution of the aspect ratios of supertall buildings are studied. Correlations of different aspect ratios with heights are proposed. Supertall buildings in two countries, China and USA were taken out to study in more detail. The average aspect ratios are calculated and compared.

Survey on Fire Risk Factors for Offices of Small and Medium Enterprises

Journal of Applied Fire Science, 2005

Fire safety for offices of small and medium enterprises (SME) established in Hong Kong is a conce... more Fire safety for offices of small and medium enterprises (SME) established in Hong Kong is a concern. The possible fire risks should be studied before determining the fire safety provisions. A long-term research project was supported and the first step is to survey on the fire risk factors in those offices. The two key factors on fire load density and occupant load factor were studied in 25 SME offices. This sample covered a large variety of businesses in engineering, advertising and trading firms. The fire load densities for the samples were found to be from 316 to 1585 MJm-2 , giving a mean of 911 MJm-2. Both the fixed and movable fire loads were analyzed. On the occupant load factor, values were lying between 4 m 2 /person to 13.33 m 2 /person, giving a mean of 7.7 m 2 /person. These two factors are important in determining the fire safety provisions in offices, both on hardware passive constructions and active fire systems. From the results, appropriate fire safety management can be worked out.

Smoke toxicity assessment of burning video compact disc boxes by a cone calorimeter

Journal of Applied Fire Science, 2002

Video compact discs (VCD) are usually stored in plastic boxes for protection. Smoke toxicity of b... more Video compact discs (VCD) are usually stored in plastic boxes for protection. Smoke toxicity of burning VCD boxes in a cone calorimeter will be assessed in this paper. Samples of the materials commonly available in the market are burnt under different radiant heat fluxes from 10 kWm-2 to 70 kWm-2. Concentrations of carbon dioxide and carbon monoxide emitted are measured. The effects to human beings will be assessed based on the fractional exposure dose (FED) measured in the cone calorimeter. Smoke toxicity effects in real-scale fires will be estimated by some correlations. It is further confirmed that very different smoke toxicity effects will be resulted from different scenarios of burning the VCD boxes.

Assessing construction elements with lower fire resistance rating under big fire

Journal of Applied Fire Science, 2005

There are proposals on using fire resisting construction and structural elements with fire resist... more There are proposals on using fire resisting construction and structural elements with fire resistance ratings lower than the values specified in the fire codes. The equal temperature-time exposure concept or t-equivalent rule is commonly applied to support the argument. However, there are concerns in applying such approach for bigger fires as the radiative heat flux acting on the construction element is not included. Fire hazard assessment on that should be watched. This is a short note on discussing possible problems associated with fire resisting construction with lower ratings. Full-scale burning tests with bigger fires are suggested to support the argument and to demonstrate that the equal temperature-time concept would work as expected.

Preliminary Full-Scale Burning Tests of Electric Cables

Journal of Applied Fire Science, 2004

Full-scale burning tests on PVC electric cables at post-flashover stage were carried out. Real-sc... more Full-scale burning tests on PVC electric cables at post-flashover stage were carried out. Real-scale room fires were considered and the heat release rates were measured. The results on the total heat release were compared with those measured from a cone calorimeter with different heat fluxes. Language: en

Decay of Buoyant Smoke Layer Temperature Along the Longitudinal Direction in Tunnel Fires

Journal of Applied Fire Science, 2004

A simple model was reported to predict the longitudinal distribution of temperature rise for the ... more A simple model was reported to predict the longitudinal distribution of temperature rise for the smoke layer along a tunnel. The longitudinal decay of excess smoke layer temperature in dimensionless form was studied by including convective and radiative heat transfer to the boundary. An expression was derived to relate to the dimensions of the cross-section of the tunnel, the depth and the velocity of the smoke layer to the temperature. A series of full-scale tests was conducted in three vehicular tunnels to verify the model. There, temperature field and smoke layer traveling velocity were measured downstream the fire source. The decay factors for longitudinal smoke layer excess temperature distributions were predicted from the model based on the smoke layer velocities and the dimensions of the vehicular tunnel. Results are then compared with those deduced directly from the measured temperature data. Good agreement was achieved. Language: en

Evacuation Studies for Tall Office Buildings in Hong Kong

Journal of Applied Fire Science, 2006

Combining Bromofluoropropene with Water Mist for Suppressing Deep Seated Wood Crib Fires

Fire Safety Science, 2014

Application of 2-bromo-3,3,3-trifluoropropene (BTP) with water mist in suppressing deep seated wo... more Application of 2-bromo-3,3,3-trifluoropropene (BTP) with water mist in suppressing deep seated wood crib fires was reported in this paper. Performance of the combination of the two clean fire suppressants was examined by laboratory scale experiments and compared with water mist and BTP used alone. Results showed that coupling of water mist with BTP could extinguish the wood crib fires with high efficiency, in which BTP discharged first could fast extinguish the flame, and the following water mist could cool the wood surface and stop glowing combustion. As a result, a complete fire extinguishment without re-strike was achieved in short time. Furthermore, hydrogen fluoride (HF) acid gas produced in the suppression process was acceptable for the use of water mist in conjunction with BTP.

Green Building Fire: Solar Chimney as an Example

With so many green constructions to develop in many places, conflicts between fire safety and gre... more With so many green constructions to develop in many places, conflicts between fire safety and green buildings have to be handled properly. Solar chimney design is a good example. Smoke exhaust in green building with solar chimney has to be designed carefully. Buoyancy can be reduced if glass walls are heated up as explained years ago. More works on further studying the possibility of compromising green and fire safety were reported by the group. Implementing safety culture is a solution to achieving fire safety with green buildings.

Is Temperature a Sixth Dimension Variable?

If Temperature is treated as the 6th dimension on top of the 5D space-time, then the 6 dimension ... more If Temperature is treated as the 6th dimension on top of the 5D space-time, then the 6 dimension manifold obeys a 4th power sum rule in place of the Fermat's quadratic sum. The Universe is contained in infinite empty 3D space and then with multi-time-dependent 5D homogenous Fermat's initiated manifolds which will continuously expand to cover the infinite 3D space. While Matters, charges, life: through the 2D nitrogenous molecular bases and intelligence representing reality are created by space-time symmetry breaking mappings by thermally exciting the Diagonal-long-range-order (DLRO) magnetic monopoles Higgs Bosons from its Temperature independent Quantum primordial Bose-Einstein condensed vacuum created in sequential times in multiple homogenous 5D space-time with arbitrary Temperature valued Fermat's manifolds. All these homogenous 5D manifolds due to Quantum theory require a rigid boundary where no eigenvalue exists. It is shown this boundary is a 4D plus Temperature enclosing boundary to these 5D homogenous space-time plus Temperature manifolds in the Universe and they are the Black Hole regions where no photons exist and masses if present behave as Tachyons.

What If Fermat's Sum is NOT the Complete Formula for the Homogenous 5D Universe Space-Time Manifold?

The Fermat's quadratic sum rule has been assumed for the Single space-time homogenous Universe ma... more The Fermat's quadratic sum rule has been assumed for the Single space-time homogenous Universe manifold such that the Universe is assumed started from a Big Bang on the initial creation of such a 5D manifold, where Maxwell's Electromagnetic vector potentials plus orthogonal monopole potentials exist. Therefore masses are created later from the space dimension projection of the monopole potentials into the inhomogeneous 4D Lorentz manifolds, as such massive objects cannot travel with a speed exceeding the speed of light 'c'. With the imposition of Quantum Uncertainty Principle, it leads to the existence of Monopole massless charge neutral Bosons with a primordial spectrum that then occupies a Higgs vacuum, such that the inhomogeneous 4D Lorentz manifold with matters can be created from a Perelmann Ricci-flow-entropy mapping. Such a thermal topological process obviously requires the Temperature parameter introduced through the Boltzmann Theorem. Such a T dimension changes the quadratic Fermat's in space-time to a 4th power equation. On the other hand in terms of Energy-momenta representation, as T becomes infinite, independent of the time of the Universe, there exists a tachyon region as postulated in science fictions with regards to astronomical space travel such as in the TV series 'Star Track' there the speed limitation can be broken by the spaceship, leading to the speculative tachyon theory. Hence, in this paper we extended the form for the homogenous 5D manifold by changing the Fermat's sum from quadratic to the 4th order, and show mathematically how such an inhomogeneous 4D manifold can exist where region masses can be tachyons when 1/T approaches 0. This domain is disjoint to the Lorentz manifold and cannot be crossed over, but serves as a light and monopole bosons reflector boundary in the partitioned homogenous 5D Universe into separated galaxies and might be verifiable from telescopic observation data of galaxies and black holes.

Minutes of the AOAFST Meeting 2021

Minutes of the AOAFST Meeting 2021 Time and Date: AEST 00:15 – 01:10 (8 December 2021) CET ... more

Several Aspects of the Big Ministorage Fires

A big ministorage fire lasting for 108 hours occurred on 21 June 2016 in Hong Kong which killed t... more A big ministorage fire lasting for 108 hours occurred on 21 June 2016 in Hong Kong which killed two firefighters. Positive pressure ventilation (PPV) was employed in the firefighting with criticisms that operating PPV led to a more hazardous fire environment rather than improving the visibility or reducing the temperature inside. Several aspects of this big fire will be reported in this talk. Firstly, different views on operating PPV for firefighting and rescue will be summarized. Ventilation arrangements including the locations of PPV and exhaust openings in a room should be carefully investigated for better understanding the efficiency of PPV in firefighting. Secondly, action of operating PPV in a room fire studied by physical scale modelling will be discussed in this talk. Temperature changes and fire spread patterns were captured. It is found that the presence of an opposite vent resulted in fire of smaller size and shorter duration. Thirdly, fire investigation should be supported by full-scale burning tests in the fire investigation report, not just by Computational Fluid Dynamics (CFD) because of storing so much combustibles in limited space. Free CFD software is commonly used and there is no guarantee that the software is appropriate for simulating such big room fires. Problems identified in the application of CFD will be discussed.

Several Safety Aspects Inside Passenger Planes

Several points to note for passenger planes safety will be presented in this talk. Firstly, possi... more Several points to note for passenger planes safety will be presented in this talk. Firstly, possible fire hazards due to using batteries, particularly the common lithium-ion batteries (LIB) are discussed. Fire or even explosion starting from batteries always occurred. Consequences of burning the combustibles inside should be watched. Smoke toxicity to human was ignored.

Ventilation provision in aircraft cabins for COVID-19 control will then be discussed. Common design equations for supporting adequate ventilation rate of 6 ACH will be introduced. Smoke management is another key point, though fire protection focusing on detection, alarm & warning, and suppression only. Nothing mentioned on removing smoke away from the aircraft cabin pressurised to 1 atmospheric pressure at high altitudes. Smoke management systems should be considered and might be integrated with ventilation control.

Fire Safety Briefing at the Hong Kong Special Administrative Region

Invited Speech at 2nd SHE Alumni Association High-Level Forum – Enterprise Compliance System Construction, 2022

The fire safety aspect of the Hong Kong Special Administration Region is briefly introduced in th... more The fire safety aspect of the Hong Kong Special Administration Region is briefly introduced in this talk. Passive protection and active firefighting are held responsible by two departments. These codes are basically prescriptive, but fire engineering approach similar to performance-based design is allowed for those projects failed to comply with the requirements. Safety culture should be enhanced.