Experimental determination of glazing efficiency in case of indoor explosions caused by accidents

Introduction. The authors present the results of testing single and double glazing, used as explosion relief structures (ERS) to ensure the explosion resistance of buildings and structures in case of indoor explosions caused by accidents. The criterion of comparative effectiveness of ERS is the value of maximum pressure inside the premises caused by an emergency deflagration explosion and the response of an explosion relief structure. The lower the maximum pressure under otherwise equal conditions (the volume of the room, the area of the relief opening, the type of the explosive mixture), the higher the ERS effectiveness. Goal and objectives. The purpose of this study is to experimentally determine the effectiveness of glazing used as an explosion relief structure in case of emergency deflagration explosions inside buildings. It is necessary to solve the following tasks to attain the pre-set goal: experimentally determine the relief pressure of ERS, or single and double glazing during an indoor deflagration explosion; determine the maximum pressure inside the explosion chamber using glazing as ERS; conduct the comparative (also numerical) analysis of the results of experimental studies to confirm the accuracy of the ERS relief pressure value; compare the results of experimental studies with the calculated values of the ERS relief pressure obtained using the methods recommended in the regulatory documents. Research methods. In the course of ERS testing, an explosion chamber, having the operating volume of 8 m3 and the relief opening area of 1.3 m2 was used. Hence, the specific area of the ERS was 0.16 m2 per 1 m3, which is 3.2 times higher than that recommended in the regulatory documents. Therefore, any pressure, exceeding the threshold values (5–7 kPa) inside the explosion chamber, unambiguously shows the ERS inefficiency. Results and their discussion. The results of testing the 4 mm single glazing and the area of 1 m2 (meeting the requirements of paragraph 6.2.30 of SP (Construction Regulations) 56.13330.2021) show that such glazing is ineffective as the ERS. Excessive relief pressure and maximum pressure in a room with an extra area of the relief opening have high values: Prel = 11 kPa; Pmax = 12 kPa. Such loadings are destructive for industrial buildings and structures. High values of relief and maximum pressures (14.7 and 17.7 kPa) in a chamber (17.7 and 20.5 kPa) allow drawing a conclusion about the inefficiency of double glazing as ERS. In the course of testing both single and double glazing, considerable glass fragment dispersion (up to 30 m deep and up to 13 m wide) was observed, which could result in the injury of people near the building during an accident. Conclusions. Experiments have shown that the assumed (calculated) glazing deflagration pressures, recommended by a number of regulatory documents and research publications, may differ significantly from the actual values, which may cause building collapses as a result of indoor explosions.