High temperature borosilicate sight glass designed for furnaces, gauges, sight windows and industrial equipment. It offers low thermal expansion, good thermal shock resistance and high light transmission. Custom sizes and 2–30 mm thicknesses are available for different applications.
High temperature borosilicate sight glass is a heat-resistant glass product designed for observation windows, sight glasses, gauges, level indicators, and other industrial applications exposed to elevated temperatures. Made from borosilicate glass, it combines low thermal expansion, good thermal stability, thermal shock resistance, and high light transmission.
The glass can be supplied as a sight glass, sight window, gauge glass, or high temperature glass sheet according to the requirements of different equipment and applications. Customized sizes and thicknesses from 2 to 30 mm are available for industrial equipment that requires reliable visual observation under elevated temperatures.
| Property | Specification |
| Material | Borosilicate Glass |
| Product Type | High Temperature Sight Glass |
| Maximum Working Temperature | <550°C |
| Available Thickness | 2–30 mm |
| Size / Shape | Customized |
| Coefficient of Expansion (20–300°C) | 3.3 ± 0.1 × 10⁻⁶ |
| Softening Point | 820 ± 10°C |
| Thermal Shock Resistance | ≥125 K |
| Refractive Index (nd) | 1.47384 |
| Light Transmission | 92% (thickness ≤4 mm); 91% (thickness ≥5 mm) |
High Temperature Resistance
High temperature borosilicate glass is designed for applications where glass components are exposed to elevated operating temperatures. The maximum working temperature of this product is below 550°C, while its softening point is approximately 820 ± 10°C.
This makes the glass suitable for observation and inspection applications in industrial equipment where ordinary glass may not provide the required temperature performance.
Low Thermal Expansion
The coefficient of expansion is 3.3 ± 0.1 × 10⁻⁶ at 20–300°C. Its low thermal expansion helps maintain dimensional stability when the glass is exposed to changes in temperature.
Low thermal expansion is particularly important for sight glass and observation window applications, where the glass may be installed in equipment that experiences repeated heating and cooling.
Good Thermal Shock Resistance
The thermal shock resistance of this borosilicate glass is ≥125 K. This property helps the glass withstand temperature changes without easily experiencing thermal stress-related damage.
For high temperature equipment, thermal shock resistance is an important consideration when selecting glass for observation windows, gauges, and other viewing components.
High Light Transmission
High temperature glass used for observation purposes needs to provide sufficient optical clarity for operators to observe equipment or processes.
This borosilicate glass provides light transmission of up to 92% for thicknesses of 4 mm or less and 91% for thicknesses of 5 mm or more. This allows it to be used for applications where visual inspection through the glass is required.
Our high temperature borosilicate glass is available in sheet and plate forms for industrial applications that require good thermal stability and resistance to temperature changes. With a low coefficient of thermal expansion of 3.3 ± 0.1 × 10⁻⁶ (20–300°C), the glass can help reduce stress caused by temperature fluctuations.
The glass can be supplied in 2–30 mm thicknesses, with customized dimensions and shapes available according to application requirements. Its high light transmission, up to 92% for thicknesses of 4 mm or less, also makes it suitable for applications where clear visual observation is required.
Depending on the equipment design and operating conditions, high temperature glass sheets can be processed into components such as observation panels, protective windows and other transparent parts for industrial equipment.
High temperature borosilicate glass can be used as a sight glass, sight window or gauge glass in equipment where operators need to observe processes, materials or liquid levels at elevated temperatures.
Typical applications include:
Industrial furnace observation windows – for viewing materials or processes inside furnaces and heating equipment.
High temperature sight windows – used in industrial equipment that requires visual inspection while operating at elevated temperatures.
Gauge and level glass – suitable for certain level indicators and process observation equipment where transparency and thermal stability are required.
Industrial process equipment – used as transparent viewing components in equipment exposed to heat and temperature changes.
For applications such as furnace sight glass or high temperature inspection windows, the appropriate glass thickness, dimensions and processing should be selected according to the actual operating temperature, thermal shock conditions and equipment design.
Qingdao Vatti Glass supplies customized borosilicate glass for different industrial applications. High temperature glass sheets and sight glass products can be manufactured according to customer requirements for size, shape, and thickness.
Available thicknesses range from 2 to 30 mm, while the dimensions can be customized for different equipment and installation requirements.
When requesting a quotation, customers can provide the required:
· Glass type or material
· Length and width
· Thickness
· Shape
· Quantity
· Application
· Working temperature
· Other technical requirements
Providing detailed application information helps us recommend a suitable glass specification for the intended use.
Qingdao Vatti Glass Co., Ltd. is a professional manufacturer and supplier of glass and specialty glass products. Our product range includes borosilicate glass, quartz glass, ceramic glass, tempered glass, laminated glass, insulated glass, and other glass products for industrial and commercial applications.
We have independent import and export rights and serve customers in international markets including Europe, America, Africa, and Asia.
Our production and quality management processes focus on product consistency, dimensional accuracy, and meeting customer specifications. We also provide customized glass solutions for customers with different size, thickness, shape, and application requirements.
For high temperature sight glass, heat-resistant glass sheets, gauge glass, and customized borosilicate glass products, please contact us with your required specifications and application details.
Looking for high temperature sight glass, sight windows or borosilicate glass sheets for your equipment?
Qingdao Vatti Glass can provide customized glass in different sizes and thicknesses according to your application requirements.
Contact us to discuss your glass specifications, dimensions, thickness and application, and get a suitable solution for your project.
1.What is high temperature sight glass?
High temperature sight glass is a heat-resistant glass component used to provide visual access to equipment operating at elevated temperatures. It can be used as a sight window, observation window, gauge glass, or other transparent viewing component.
2.What is the maximum working temperature of this borosilicate glass?
The maximum working temperature listed for this product is below 550°C. The actual glass selection should also consider the equipment design and other operating conditions.
3.What thicknesses are available?
The available thickness range is 2–30 mm. Customized dimensions and thickness requirements can be discussed according to the application.
4.Can the high temperature glass sheet be customized?
Yes. The glass can be supplied in customized sizes and shapes according to the requirements of different equipment and applications.
5.Can this glass be used for furnace sight windows?
Yes. High temperature borosilicate glass can be used for furnace observation windows and other high-temperature viewing applications when the operating conditions are within the applicable specification.
6.What is the difference between high temperature glass and ordinary glass?
High temperature glass is designed for applications involving elevated temperatures and temperature changes. Borosilicate glass has a low coefficient of thermal expansion and good thermal shock resistance, making it suitable for applications where ordinary glass may not provide the required thermal performance.