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Metal fused sight glasses- Metaglas®

Sight glass luminaires

Sight glass fittings /
techincal glass

What is Metaglas?

Since it was developed in the 1970s, METAGLAS® has been known as the safest sight glass in the world. A number of chemical and manufacturing companies (Bayer, Hoechst, BASF) collaborated to create METAGLAS, and to establish the standard with which it complies and by which all other sight glass is measured, a standard now called DIN7079.

METAGLAS was created to improve safety conditions within plants that handled corrosive chemicals, chemicals worked at high temperatures and those worked under high pressures. The safety concerns became serious enough that competing companies joined forces to create METAGLAS.

How it IS Made?

METAGLAS products are made by melting glass inside a circular metal frame, thereby fusing the glass and metal. As the glass cools and solidifies, the difference in the linear coefficient of thermal expansion between glass and metal creates a uniform compressive stress throughout the glass. The glass prevents the metal ring from shrinking back to its theoretical size upon cooling and it remains in tension.

The high degree of mechanically induced compressive stress caused by this physical relationship between the metal and glass makes METAGLAS the strongest and most secure glass for sight window or visual flow indicator applications.

Even at the most extreme temperatures (as high as 280°C/536°F) or in overpressure situations, sudden, total failure – that involves explosive shattering of the glass – has never been reported.

The Veriety of MeTAGLAS

METAGLAS sight windows are available in numerous products including visual flow indicators, sight glass windows, sanitary fittings and gauge glass. These glass elements provide a level of safety and duration of service that goes well beyond that provided by conventional tempered glass or plastic.



In addition to offering excellent transparency, METAGLAS mechanically prestressed windows are considered the strongest, most secure sight glass elements available


Advantage Metaglas

METAGLAS was created during a period of industry-wide collaboration where competitor companies worked together to devise a product that would make their manufacturing facilities safer. Herberts Industrieglas has expanded the use of METAGLAS to encompass nearly every industrial situation in which visual observation is required where dangerous chemicals are used, or used at high temperatures or high pressures. The use of METAGLAS has significantly reduced the risks to workers in and around these plants.

METAGLAS  is really one thing: safe. Conventional sight glasses cannot withstand a crack. METAGLAS  only cracks on the surface so no failure occurs in the event of damage.

Unpopular cleaning an deposit problems can be solved because METAGLAS is free of dead spaces aswell as it is flush with the wall.
METAGLAS is also very inexpensive. Aside from that it can be installed without any problems, has a long service life and offers the most effcient operational reliabitlity.

See video made by L.J. Star on youtube: Link

What is special about Metaglas Sight Glass?

Metal fused sight glasses consist of a viewing window that is sorrounded by a metal ring. The different coefficients of thermal expansion of glass and metal create a homogeneous state of compressive stress in the glass body. If the metal heats up, the glass melts and bonds with the steel. When the steel cools down, it contracts and thus shrinks the glass. The sight glass is therefore to be understood as a composite.

Any Questions?

We are happy to take the time to create an individual solution for you and to advise you extensively. Leave your contact details and we will contact you!