## 3 Results
This leads to a decrease in pressure, the rate of which is determined by the area of the additional opening. For instance, if the area of the additional opening is 3.34% of the overall EVS surface, or 0.1 m\({}^{2}\) (curve B, Figure 9), the pressure does decrease, although insignificantly. If the area of the additional opening is increased to 0.25 m\({}^{2}\), which constitutes 8.35% of the total EVS surface area, a significant drop in pressure occurs, and the maximum explosion pressure does not exceed the protective-structure-collapse pressure at the additional opening, \(P_{shd}\) (curve C, Figure 9). A further increase in the area of the additional opening, up to 0.5 m\({}^{2}\), which is 16.7% of the total EVS surface area, leads to an abrupt decrease in explosion pressure at the moment of panel opening (curve D, Figure 9). In terms of the blast resistance of the building, a further increase in the area is unreasonable. Let us take a look at how the parameters of the devices covering the additional opening affect the level of explosion loads. Figure 10 provides explosion-pressure relationships in a kitchen with various dimensions assumed at the first portion of calculations (Figure 9). The total area of the opening is 3 m\({}^{2}\). The response rate of the EVS covering the opening is 0.5 kPa (about 50 kT/m\({}^{2}\)). Figure 10 (relationship A) demonstrates explosion-pressure dynamics inside a room with an EVS-equipped opening (dimensions indicated). Curve B (Figure 10) depicts explosion pressure if an EVS with an additional opening is used. The area of the additional opening is 0.25 m\({}^{2}\), which is 8.33% of the total opening area. The additional opening is equipped with EVSs with a response rate of 0.5, 0.25, 0.125, and 0.05 kPa, which open up when the pressure reaches 2.05 kPa, and the EVSs have divisions (100 elements each). The explosion-pressure values, which will be registered in the kitchen when the indicated protection structures are used, are shown in Figure 10 (curve B). The explosion pressure observed when the additional opening is covered with a crushable membrane (crushes when pressure equals 2.05 kPa) is given in Figure 10 (curve C). Apart from that, Figure 10 shows the relationship between the explosive pressure inside the premises and previously and fully open discharge windows (curve 1, Figure 10). When using EVSs with fewer division applied to the additional opening, the pressure-dropdown effect is less significant. This is illustrated by the calculations shown in Figure 11, which provides explosive-pressure values when an EVS with no divisions is used in the additional opening. The EVS opening pressure is 2.05 kPa, and the response rates of the structure are 0.05 and 0.125 kPa. It can be deduced from Figure 11 that the best effect is achieved when the additional opening (quite small vent window) in the overall structure of the main sheddable window is cleared almost instantly. This can be achieved by multiple divisions of the covering material used on the additional opening of the EVS or by using a crushable membrane,  
Figure 11: Excessive pressure of an explosion inside a kitchen: A—non-upgraded EVS; I—additional opening is covered with an EVS with a response rate of 0.05 kPa; II—additional opening is covered with an EVS with a response rate of 0.125 kPa; I—explosive pressure inside the kitchen with a fully open window area. Figure 10: Excessive pressure of an explosion inside a kitchen: (**A**) non-upgraded EVS; (**B**) EVS equipped with an additional 0.25 m\({}^{2}\) opening covered with an EVS that opens when pressure reaches 2.05 kPa; response rates are 0.5, 0.25, 0.125, and 0.05 kPa; (**C**) opening covered with a crushable membrane (glass); I—explosive pressure inside the kitchen with a fully open window area. like glass, for instance, which breaks down into multiple fragments. From the physical perspective, an EVS with multiple divisions has a high response rate (curve C, Figure 10).