Glass  |  Tempering Lines  | Heat Soak Test Furnaces
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Specifications subject to change without notice.
Max. Operating Temperature : 350C
Temperature Control : By a PLC
Temperature Uniformity : By high speed circulation fans
Switching Device : Contactor with Surge Suppression / SSR - Solid State Relay (optional)
Thermocouple : Type J (Fe-Const)
Thermal Insulation : Rockwool
Safety : A switch de-energizes heating elements when the door is open
Door Opening : Manual
Truck Movement : Manual by man power / By mechanical drive (optional)
Body Construction : Welded steel structure
Coating : Thermoset powder coat
Standard Color : Beige (RAL 7032 W) + Orange (RAL 2004 W) - Other colors on request.
Connection : Three Phase + Neutral + Earth
During the toughening process the glass is heated up to temperatures of 620C. The NiS changes from beta phase to alpha phase at 380C which in turn changes its volume. When the glass is rapidly cooled during the air quench, the NiS does not have time to return to the beta phase and is therefore 'frozen' in an unstable form. Over a period of time the alpha phase will slowly convert to the beta phase with an increase of about 2 - 4% in volume. If the NiS is in the central tensile zone and the increase in size is big enough, it will initiate a crack which will propagate and cause glass breakage. As the rate of change from alpha - beta phase is temperature/time dependent, the hotter the glass the quicker the reaction takes place and the sooner the breakage will occur (This is the theory behind the Heat Soak Test).