Glass fire protection: Pyran S borosilicate glass can be installed in facades. Formats of up to 3.6 × 1.8 m are possible without additional mechanical support in the form of clamping.
In the following interview with GW-News, Juliane Brandt-Slowik and Helmut Kugelmann from Schott Technical Glass Solutions GmbH (TGS) discuss the special features of borosilicate glass compared to standard soda-lime glass. Their special focus will be on the thermal and mechanical properties as well as the possibilities borosilicate glass offers as fire-resistant glass.
GW-News: Ms Brandt-Slowik, what distinguishes borosilicate glass from soda-lime float glass, which is the standard product in the flat glass industry?
Here is a glass roof in which Pyran S borosilicate glass from Schott was used.
Juliane Brandt-Slowik: Soda-lime glass is the widely used standard glass in many applications such as architectural and automotive. In contrast, borosilicate glass, such as Borofloat 33, is characterised by outstanding chemical and thermal properties. It is particularly resistant to aggressive chemicals and temperature changes, which makes it the first choice in laboratories.
GW-News: How does the structure of the glass affect its properties?
Juliane Brandt-Slowik: The structure of a glass depends on its composition. In borosilicate glass, a cross-linked network of silicon dioxide and boron oxide forms a stable structure. In comparison, the high proportion of network modifiers, such as sodium oxide and calcium oxide in soda-lime glass, leads to a less stable structure.
GW-News: Can you tell us something about the thermal properties of borosilicate glass?
Juliane Brandt-Slowik: The coefficient of thermal expansion of borosilicate glass is lower than that of soda-lime glass, which makes it more resistant to thermal shock. This thermal stability also makes borosilicate glass an ideal choice for fire-resistant glazing.
Helmut Kugelmann: Due to the fact that the softening point is at higher temperatures, the glazing remains stable in fire tests. This makes it possible to use large glass formats (e.g. 3.6 × 1.8 m) without the need for additional mechanical support in the form of clamping. With mechanical clamping, on the other hand, it is possible to withstand the fire for 120 minutes due to the low flow behaviour.
Borosilicate glass is more resistant to scratching and abrasion than soda-lime glass. It can withstand higher loads before cracks appear.
Schott
GW-News: So borosilicate glass is also suitable for larger glass formats, e.g. for facades?
Schott
Pyran S borosilicate glass can protect buildings from the spread of flames from floor to floor (horizontally & vertically) as well as from one building to the next.
Helmut Kugelmann: Yes, the unique composition and structure of borosilicate glass makes it possible to combine large dimensions of glass with simple frame systems. This offers the architect and designer creative freedom in favour of the aesthetics and appearance of the building. The Schott borosilicate glass Pyran S can ideally protect buildings from the spread of flames from floor to floor and from one building to the next (horizontally & vertically).
GW-News: Which applications benefit from borosilicate glass, and in which thicknesses?
Helmut Kugelmann: In the fire protection sector, Pyran S is used not only in buildings but also in ship and railway glazing as well as glazing for lift doors.
Juliane Brandt-Slowik: Borosilicate glass is used in many areas, including laboratories and household appliances such as pyrolytic ovens. At Schott, floated borosilicate glass, for example Borofloat 33, is available in a comprehensive range of thicknesses from 0.7 to 25.4 mm and has been manufactured in Germany for 30 years.
The composition and structure of borosilicate glass allows for large dimensions, so pane formats of 3.6 × 1.8 m are currently available from Schott.
Schott
GW-News: How do you assess the future use of borosilicate glass, will demand increase?
Juliane Brandt-Slowik: With its exceptional properties, borosilicate glass will continue to be in demand for a wide range of applications. Further research and development with the glass could lead to even more versatile applications. In addition, it can be said that a Schott Borofloat 33 has a significantly higher scratch and abrasion resistance and a higher load is required to trigger cracks in the material. In the basalt grit impact test, it is more resistant, which also leads to reduced haze.
Helmut Kugelmann: Future applications for Pyran S can be seen in glass smoke barriers, for example in department stores and underground stations, to keep escape routes smoke-free.
The questions were asked by Matthias Rehberger
About the interviewees
Juliane Brandt-Slowik
is Business Development and Sales Manager at Schott Technical Glass Solutions (TGS).
Schott
Helmut Kugelmann
is Head of Product Group Fire Resistant and Security Glazing Schott Technical Glass Solutions (TGS).
