Product Overview
Tempered borosilicate stepped sight glass is used for direct visual inspection in pressurized process equipment. It is selected where clear visibility, low thermal expansion, and strong resistance to thermal cycling are required.
This product is also commonly described as stepped sight glass, borosilicate sight glass, transparent sight glass, and tempered sight glass. It is manufactured in 3.3 borosilicate glass and is intended for applications where chemical resistance and low thermal expansion are important.
Typical Applications
Stepped sight glass is used in process vessels, transparent level gauge assemblies, and boiler sight-glass service where visual inspection of the medium is required. Technical information states that this type of sight glass is used under pressure and thermal or chemical stress, and that glass attack can increase significantly with temperature and pH in aqueous service.
Material and Performance
The material data sheet for tempered borosilicate sight glass lists a thermal expansion coefficient of 3.3 × 10⁻⁶/K, density of 2.23 g/cm³, thermal shock resistance of 230 K, transformation temperature of 560°C, and highest short-term working range of 500°C. The same data sheet also lists hydrolytic resistance HGB 1, acid resistance class S1, and alkaline resistance class A2.
Key Advantages
This sight glass is designed for stable visual monitoring in demanding industrial service. The data shows low thermal expansion, high short-term heat resistance, and DIN 7080-controlled dimensional and optical checks, including bubble control, marking checks, edge tolerance checks, and limits on crystalline inclusions.
Technical Parameters
| Item | Specification |
|---|---|
| Material | 3.3 borosilicate glass |
| Product type | Stepped sight glass / tempered sight glass / borosilicate sight glass |
| Standard | DIN 7080 |
| Thermal expansion coefficient | 3.3 × 10⁻⁶/K |
| Density | 2.23 g/cm³ |
| Refractive index | 1.472 |
| Transformation temperature | 560°C |
| Highest short-term working range | 500°C |
| Thermal shock resistance | 230 K |
| Hydrolytic resistance | HGB 1 |
| Acid resistance | Class S1 |
| Alkali resistance | Class A2 |
| Quality checks | Bubbles, markings, edge tolerances, viscous knots, crystalline inclusions |
| Special dimensions | Available on request |
Common Sizes
| Diameter / Length | Thickness | Visible Diameter | Pressure Resistance |
|---|---|---|---|
| 63 mm | 10 mm | 48 mm | 16 bar |
| 80 mm | 12 mm | 65 mm | 16 bar |
| 100 mm | 15 mm | 80 mm | 16 bar |
| 125 mm | 15 mm | 100 mm | 10 bar |
| 125 mm | 20 mm | 100 mm | 16 bar |
| 150 mm | 20 mm | 125 mm | 10 bar |
| 150 mm | 25 mm | 125 mm | 16 bar |
| 175 mm | 20 mm | 150 mm | 10 bar |
| 175 mm | 25 mm | 150 mm | 16 bar |
| 200 mm | 20 mm | 175 mm | 8 bar |
| 200 mm | 25 mm | 175 mm | 10 bar |
| 200 mm | 30 mm | 175 mm | 16 bar |
| 250 mm | 25 mm | 225 mm | 8 bar |
| 250 mm | 30 mm | 225 mm | 10 bar |
