A low-cost and easily-realized sensing device used for the detection of gas mixtures at different concentrations is presented. Its sensing part includes a small critical nozzle, a laminar structure, and a differential pressure sensor. When gas flows through the laminar structure, there is a pressure drop between both ends of it, and for different components of gas, the pressure drop is different. Based on this feature, the concentration detection is achieved. Concentration tests for two types of fire extinguishing agents CBrF₃ and C₃HF₇ are presented. The results show the characteristics of fast response/recovery time, high accuracy, and good repeatability. Based on the theoretical analysis, the effects of the design parameters on the sensing performance to concentration detection are discussed in detail.

As research on the concentration distribution for evaluating the effectiveness of a gas fire extinguisher system is quite important, the proper sensing technology is necessary. Here, a simple method used for measuring the concentration of agent is introduced, and the manufacture of the sensing part is described clearly. The sensing unit is composed of a pressure reducing structure and pressure sensor element. The detection was achieved by sensing the change of pressure difference caused by gas flow. In order to verify the theory and characterize the sensing performance, two types of fire extinguishing agents, bromotrifluoromethane (CBrF ₃ ) and heptafluoropropane (C ₃ HF ₇ ), were used in the experiments. The results showed a high sensitivity from 0 to 100%, good repeatability and fast response/recovery time. Furthermore, the effect of operating temperature, humidity and geometric structure on the response were investigated. Measurements showed, for CBrF ₃ , that the temperature had a linear impact on the response and the influence of humidity in the sensor was negligible. Through the analysis of the geometry parameter, it was found that the sensing performance could be greatly improved through adjusting the geometry structure. This technique provides a low-cost and highly reliable sensor for the detection of gaseous extinguishing agent that can be easily fabricated.

It is very important to understand the heat transfer process between storage tanks in a tank farm under a fire scenario, which is one of the key factors in determining the consequences of accident development. In this paper, a CFD simulation is used to study the heat transfer process and emergency protection of tanks under a fire scenario. The simulated results show that the changes in wind speed can affect the heat transfer of the tank farm. The highest temperature of the tanks at 5.3 m/s (wind speed) is 1432 K, while the highest temperature at 17.1 m/s (wind speed) is 1556 K. At the same time, the changes in wind direction can also affect the heat transfer of the tank farm. For the 45° east by north (wind direction), almost all tanks in the tank farm are affected by the fire. When the water curtain was applied as an emergency protection measure, the simulated highest temperature of the tanks decreased to 779 K (the cooling water intensity 6 L/min·m²), while the highest temperature of the tanks was 1432 K without water curtain protection under the actual fire conditions. The simulated highest temperature of the tanks decreased to 671 K when the emergency thermal insulation coating was sprayed on the surface of the tanks, which can effectively protect the adjacent tanks from being destroyed.