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Fire Protection and Prevention
Published in W. David Yates, Safety Professional’s, 2015
An employer is responsible for ensuring that the inspection, maintenance, and testing of all portable fire extinguishers are conducted. Portable fire extinguishers shall be visually inspected monthly. Furthermore, the employer shall ensure that each portable fire extinguisher is serviced annually and tested in accordance with Table 10.2.2
Working safely in an engineering environment
Published in David Salmon, Penny Powdrill, Mechanical Engineering Level 2 NVQ, 2012
If a fire is tackled when it is small there is less chance of it getting out of control. You can tackle a small fire with a portable fire extinguisher. Care must be taken to select and use the appropriate type of extinguisher for the type of fire, as it can be dangerous to use an inappropriate appliance, particularly if there is an electrical supply in the fire. When fighting a fire always ensure your escape route is clear. Fire extinguishers work by either preventing the oxygen from reaching the flames or by removing the heat from the fuel; some types of fire extinguishers work in both ways. The most common types of fire extinguishers only last for about 20–45 seconds so they must be used efficiently and with care for best results. Shown below are the most common types of extinguisher, together with the types of fire for which they are most effective.
Unilateral Blow-Off and Periodic Smoldering Holes in Upward Flame Spread Over Thin Charring Material
Published in Combustion Science and Technology, 2022
Wenlong Wang, Jun Fang, Luyao Zhao, Yue Zhang, Jinjun Wang, Yongming Zhang
To sum up, the surface smoldering is more remarkable in high carbon dioxide diluted environments such as the fire scene after the application of the carbon dioxide fire extinguisher. The persistent and stable existence of these smoldering regions brings enduring security risks below conventional detection to the fire site and can evolve into flaming again once the external ventilation conditions are improved, resulting in a secondary fire hazard. Based on the above analysis, it is suggested that a secondary fire extinguishment using cold water or silver sand is essential to thoroughly eradicate the potential solid-phase smoldering regions after the elimination of the visible gas-phase flame, ensuring the intrinsic safety of the fire site.
Development of interaction model on the risk assessment method for nuclear facilities using a system model with a multi-layer structure
Published in Journal of Nuclear Science and Technology, 2021
Kenji Mori, Hitoshi Muta, Yasuki Ohtori
Basic EPLs are extracted from the constructed multi-layer. Figure 12 shows 4 EPLs, namely EPL1 to EPL4, as examples of extracted EPLs. Each EPL is explained below. EPL1:A fire breaks out from the GB A and the heat propagates through the processing room. The propagated heat is detected by Fire detector A, and the temperature information of the processing room is transmitted to the supervisor. The supervisor instructs the ARCs A to extinguish the GB A fire, and the ARCs A move on the Access route while reporting the status to the supervisor. Simultaneously, the heat transmitted from the processing room to the Access route A affects the ARCs A. A small Loop is formed between the supervisor and the ARCs A, but no Loop is formed between the GB A and the supervisor, therefore, EPL1 can be defined as an Unclosed Line, and there is a possibility that the GB A fire cannot be extinguished in this situation.EPL2: Same as the EPL1, other than replacing ‘A’ with ‘B.’EPL3: A fire breaks out from the GB A and the heat propagates through the processing room. The propagated heat is detected by Fire detector A, and the temperature information of the processing room is transmitted to the supervisor. The supervisor instructs the ARCs A to extinguish the GB A fire. The ARCs A extinguish the GB A fire by operating the fire extinguisher A in the processing room and releasing the fire extinguishing agent (i.e. fire extinguishant or fire extinguishing composition) from Fire extinguisher A while reporting the status to the supervisor. The supervisor recognizes the fire extinguishing status of the GB A by the information from Fire detector A and the report of ARCs A. The heat in the processing room affects the ARCs A and Fire extinguisher A. This EPL forms a Loop.EPL4: Same as the EPL3, other than replacing ‘A’ with ‘B.’
Sensitivity analysis of risk assessment for continuous Markov process Monte Carlo method using correlated sampling method
Published in Journal of Nuclear Science and Technology, 2023
Yuki Morishita, Akio Yamamoto, Tomohiro Endo
The following procedure is used to analyze the state of the system using the CMMC and the correlated sampling methods. At the initial state of the analysis, the function of the normal cooling systems of the two spent fuel pools are assumed to be lost (LUHS). At time , the fire extinguisher pumps in SFP 1 and 2 are intact and the fire trucks in SFP 1 and 2 are on standby.Calculate the failure probability of the fire extinguisher pumps within a time step when the fire extinguisher pumps are intact.Calculate the startup rate of a fire truck when the fire extinguisher pump is broken. The startup rate (probability of startup per unit time) of a fire truck depends on the status of another SFP. The startup rate is decreased when another SFP has reached the fuel damage. This dependency will be explained in section 3.3.At each time step, determine the state of the equipment at the next time step by comparing the failure probability and startup probability with the uniform random numbers between 0 and 1. For a fire extinguisher pump, failure is assumed when (random number) < (failure probability), and for a fire truck, the startup is assumed when (random number) < (startup probability). If the inequality is not satisfied, the condition in the current time step is unchanged.Update the weights of the correlated sampling method from the failure and startup rates, their perturbation rates, and time step widths. Equations (6) or (7) are used to calculate weights.Repeat steps (2) through (5) until the end of analysis time to obtain accident scenarios and weights for each time step.Repeat steps (1) through (6) for the number of samples to obtain accident scenarios and weights.From the accident scenarios and the weights for each time step, 1) the existence probability of each system state in the base and perturbed conditions, 2) the cumulative failure probability of each component, and 3) the fuel damage frequency in each SFP are obtained. The average water temperature and water level at each time step in the base condition are also obtained.From the existence probabilities of each system state, the following quantities are obtained: (i) the cumulative failure probabilities of the fire extinguisher pumps, (ii) the cumulative startup probabilities of the fire truck, (iii) the fuel damage frequencies in the base and perturbed conditions, (iv) the change of these probabilities or frequencies between the base and the perturbation conditions.