Fire

Petrochemical fires pose severe threats to public safety and environmental sustainability, necessitating urgent advancements in efficient and eco-friendly fire suppression technologies. This study systematically investigated the influence of gas–liquid ratio (GLR) on the foam properties and fire suppression efficacy of a novel short-chain fluorocarbon (PFH-BZ) foam fire extinguishing agent. Through comprehensive experimental analysis, the underlying mechanism governing foam performance was elucidated, and the burn-back resistance of optimized formulation was evaluated. The results indicate that GLR significantly impacts PFH-BZ foam performance. Foaming capacity and structural stability exhibit a positive correlation with increasing GLR until reaching a plateau. Low GLRs result in insufficient foam formation and thermal stability, while inducing detrimental combustion intensification. Conversely, excessively high GLRs impair foam spreading capacity, hindering rapid extinguishment. The optimal fire extinguishing performance is achieved at a GLR of 12, where PFH-BZ foam attains an excellent balance among drainage characteristics, spreading capacity, and structural stability. This optimized formulation achieves complete extinguishment within 26.16 s and maintains burn-back resistance of 662.37 s while effectively mitigating the vapor explosion phenomenon. These findings provide critical guidance for the application of a PFH-BZ-based foam extinguishing agent and deepen understanding of the influence of system parameters on suppression performance.

To improve the fire safety performance of fire protection renovation projects for existing public buildings, this paper systematically sorts out and analyzes relevant research studies, accident reports, and fire protection renovation codes and guidelines. It constructs a fire performance evaluation system for such projects, including 4 first-level indicators—”Building Characteristics”, “Building Fire Protection and Rescue”, “Fire Facilities and Equipment”, and “Heating, Ventilation, Air Conditioning (HVAC) and Electrical Systems”—and 19 second-level indicators such as “Building Usage Function”. The subjective–objective combined weighting method of Analytic Hierarchy Process (AHP)-CRITIC is adopted to determine the weights of indicators at all levels. Four high-weight second-level indicators are selected as core remediation objects: average fire load density, floor layout, automatic fire alarm and linkage control system, and electrical systems. Meanwhile, the evaluation system is converted into a Bayesian Network model, with an empirical verification analysis carried out on a shopping mall in Chaoyang District, Beijing, as a case study. Results show that the approach of combining partial codes with the rectification of high-weight indicators can reduce the fire occurrence probability of the mall from 78%, before renovation, to 24%. Therefore, the constructed evaluation system and Bayesian Network model can realize the accurate quantification of fire risks, provide scientific and feasible technical schemes for the fire protection renovation of existing public buildings, and lay a foundation for enriching and improving fire protection assessment theories.

Firefighting requires high and multidimensional fitness to ensure operational readiness and public safety. In Portugal, there is limited data regarding firefighters’ fitness and exercise programs to improve readiness are lacking. This study evaluated the effects of a 6-month minimal-equipment exercise program on the physical fitness of firefighter recruits. Thirty-five male subjects (23.0 ± 2.72 years) were assessed at baseline,3 and 6 months for body composition, handgrip strength, running speed, cardiovascular endurance, anaerobic power, and upper- and lower-body strength. The intervention entailed daily sessions with 15 min of continuous running (50–65% HRmax) and active stretching, followed by alternating routines, including endurance running, free weights, interval sprints, calisthenics, and drills. A repeated-measures ANOVA and Bonferroni adjusted post hoc comparisons identified time-based changes. Significant improvements occurred across all fitness variables. Body fat fell by 8.4% and VO₂max increased (p < 0.001), surpassing occupational thresholds required for extended suppression tasks. Bench press and sit-up performance improved by 88% and 81%, respectively, while countermovement jump showed double-digit gains (13%), all of which can translate directly to hose advancement, victim rescue, and forcible entry. These results highlight that resource-constrained departments can implement effective, low-cost exercise programs for enhancing pivotal fitness components, supporting policy initiatives to include structured training throughout firefighters’ careers.