Glass can be a dangerous material. When standard annealed glass breaks, it forms potentially lethal shards and splinters. The reputation for dangerous fragility is however fast disappearing.
Glass manufacturers have developed a range of safety glasses adding strength and integrity to this beautiful building material and allowing glass to be used in areas where safety is critical and in unprecedented situations.
Security is now also possible with glass. A range of high performance glasses allows light and vision into areas formerly excluded from natural light. Situations where customer interface and high security must coexist, need no longer seem threatening and unfriendly. There is a glass in the DUAL SEAL GLASS range to meet virtually any safety and security needs.
Safety glass is defined as glass which must have passed an impact test (currently EN12600:2002 pendulum impact test for glass in buildings) and either must not break or must break safely.
There are three levels of impact: 1, 2 and 3, 1 being the highest. Each involves the glass being impacted by a twin tyre design. (The test roughly simulates the impact of a child weighing 100lbs [45kg] hitting the glass with varying degrees of force.)
Three generic types of glass meet the requirement of this British Standard:
- Laminated Glass (B)
- Toughened Glass (C)
- Wired Safety Glass(only to a limited extent see Wired glass)
All Security Glasses (see following section) automatically qualify as level 1 safety glasses.
There are two types of laminated glass: PVB laminated and cast resin laminated glass. PVB laminated is the more commonly used variety.
PVB laminated safety glass
Two or more sheets of glass are bonded together with one or more layers of polyvinyl butyral (PVB), a plastic interlayer in sheet form. The principal benefit of laminated glasses is their performance under impact.
The glass may fracture but any broken fragments will remain firmly bonded to the interlayer.
The interlayer also absorbs impact energy, reducing the risk of penetrating the panel. When properly glazed, even safety grade laminates will resist attack, acting as a deterrent to burglars and normally remaining in place until replacement is convenient.
Depending on the arrangement, number and thickness of glass sheets and interlayers in the construction of the laminated glass, different levels of protection are possible including against firearms and explosions.
The interlayer in laminated glass provides two additional benefits:
- sound transmittance is reduced, particularly at the higher frequencies
- Ultra-violet radiation (between 320 and 380 nanometres) is reduced by up to 99%.
For more information on the PVB laminated glass range from DUAL SEAL GLASS please contact technical sales office.
Resin laminated safety glass
Resin laminated glass is manufactured by pouring liquid resin into the cavity between two sheets of glass which are held together until the resin cures.
Also sometimes referred to as cast-in-place laminated glass, this method is ideal for laminating glass having a heavily textured or patterned surface.
It is also possible to add a wide variety of colours to the resin for decorative effect. Not all resin laminates have safety performance. They are principally used for decorative and acoustic purposes, where safety performance is normally of secondary importance.