Bulletproof aluminum windows – are a product being one of the answers to the growing interest in construction joinery with an enhanced level of security. Next to anti-burglary safeguards, the level of protection against firearm discharge is a significant parameter of the window joinery in many buildings.
It is no accident that bulletproof windows are included in the group of special purpose glass-aluminum products. Bulletproof windows are tasked with protecting people and property against the effects of firearm discharge, which is why the design of such partitions, depending on their bullet resistance class, should guarantee resistance to perforation by various types and calibers of bullets discharged by different types of firearms throughout their entire surface. All components of a bulletproof window meet very high quality requirements, so every joint between these components must ensure real protection against penetration of the structure by bullets. Windows of this type are installed in places at particular risk of assault with the use of firearms or terrorist attack.
- in situations that are difficult to imagine in daily life - ensure direct protection of human life and health. The bullet resistance class of partitions adapted for protection against firearm discharge is a critical issue. The parameter of resistance to bullet penetration, characterizing construction joinery products, is given in standard EN 14351, which pertains to windows and doors. The degree of window protection against firearm discharge is defined by classification standard EN 1522, and the method of testing windows’ resistance to bullet penetration is set forth in testing standard EN 1523. The bullet resistance of window fillings – requirements for and classification of glazings – is given in standard EN 1063. The appropriate bullet resistance class of glazings is required to ensure the bullet resistance class of the entire window structure.
is subject to standard EN 1522. It divides all partitions, including windows, into eight bullet resistance classes; seven basic bullet penetration resistance classes, as well as an additional class for hunting firearms. Designations from FB1 to FB7 are assigned to the basic bullet resistance classes, and the FSG designation is assigned for hunting firearms. These classes are graded from 1 to 7, meaning that class FB1 covers window designs with the weakest resistance to bullet penetration, and class FB7 covers the windows with the best protection against bullets discharged from firearms. A lot of data is taken into account when classifying windows into the appropriate bullet resistance class. This data includes the types of firearms, bullet type and material, bullet design, mass and shape, the caliber of the firearm and barrel length. Besides this, the distance of firing and bullet velocity are also taken into consideration. Every factor has an influence on the determination of a partition’s resistance to bullet penetration. Firearm type and caliber; short-barreled guns (handguns) in the form of pistols and revolvers, long-barreled guns in the form of rifles, and in the case of hunting firearms - shotguns. The mass and velocity of bullets, as well as the distance to the target, have an influence on the kinetic energy that must be neutralized by the structure of the bulletproof window. The material from which the bullet is made (lead, copper, steel), its construction (core) and shape (flat, rounded, conical, pointed) are equally important factors. The lowest class, FB1, ensures protection against firing from a sports firearm of caliber 5.6 mm of lead bullets with a rounded shape and a mass of 2.6 grams, fired from a distance of 10 meters at a velocity of 360 m/s. The highest class, FB7, affords protection against a 7.62 mm caliber rifle with a barrel rifled over a length of at least 254 mm, firing pointed, hard-core steel bullets with a mass of 9.8 grams at a velocity of 820 m/s from a distance of 10 meters. Bulletproof windows should withstand firing from various types of firearms, hence their precise classification, making it possible to specify the parameters of resistance to bullet penetration and facilitate selection and application adequate to the threat level.
in every bullet resistance class is based on reinforcement of the frame, glazing with bulletproof glass of the appropriate class and sealing of the contact edge between the frame and the glass against bullet penetration. The frame of a bulletproof window fundamentally differs from a typical window frame; it is clad or filled with materials absorbing bullets’ kinetic energy and preventing perforation. Moreover, in higher bullet resistance classes, window frames are additionally reinforced at the corners. Windows are glazed with glass classified according to standard PN-EN 1063 into a class corresponding to the designed bullet resistance class of the entire structure according to standard PN-EN 1522. Bulletproof glass constitutes a glazing that is very well thought out in a technological sense and consists of properly selected layers of glass combined into a single pane by lamination. According to standard PN-EN 1063, bullet penetration resistance is divided into seven basic classes; from the lowest, BR1, to the highest, BR7, and a class for hunting firearms, SG2. It is accepted that the minimum bullet resistance class of glazings applied in window designs should correspond to the bullet resistance class of windows according to standard PN-EN 1522. For example, glazing of class BR1 or higher should be applied for a window of class FB1. A window of class FB2 must be filled with glass of at least class BR2, and an analogous scheme of glazing selection pertains to windows in classes FB3, FB4, FB5, FB6 and FB7. Glazing of class SG2 is applied in windows of class FSG. Besides the classification of bullet penetration resistance, bulletproof glass is designated as “S” - unprotected against splintering during firing, and as “NS” – i.e., non-splintering. The proper mounting of the glazing in the bulletproof window frame is a very important issue, particularly protection of the contact edge between the glazing and window frame. Even bulletproof glass of a high class will not provide an adequate ballistic screen if it is not properly installed.
Bulletproof aluminum windows find applications in buildings at risk of assault with the use of firearms and terrorist attacks. Prior to classification into a specific bullet resistance class, every type of window is tested very precisely according to standard PN-EN 1523. Prior to commencement of ballistic tests, the window’s design is analyzed in order to identify its potential weak points, and on this basis, targeting areas are designated during bullet penetration tests under laboratory conditions. Thus, every type of window must earn its bullet resistance class with its design solutions, materials and glazing applied, and precision of manufacture. Bulletproof windows are commonly applied in military, police and sporting shooting ranges. They are also installed in penitentiaries and jails. They also serve for securing currency exchanges, jewelry stores, banks and post offices. In military facilities, bulletproof windows are installed in guard buildings, offices of the on-duty officer, and as serving windows in offices and arms warehouses. Modern bulletproof designs not only protect people and property against firearm discharge but are also characterized by a very high level of anti-burglary protection.