Flat Quartz Sight Glass
Quartz (fused silica) circular sight glasses excel in high-temperature environments due to their superior clarity and resilience to thermal shock. Their low thermal expansion makes them perfect for use in furnaces, boilers, and reactors, where maintaining visibility is critical.
OUR WARRANTY
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Douglass warrants merchandise against defective workmanship and materials that become apparent within a period of 12 months from the date of receipt of invoice by the purchaser (hereinafter referred to as the warranty period). All liabilities under the warranty provisions shall expire when the warranty period has expired. Please feel free to contact us if you have any questions or comments.
SHIPPING AND PACKAGING
At Douglass, we use a unique and patented packaging method that minimizes the risk of glass damage during shipping. This system ensures your products arrive in perfect condition, just as we would like to receive them ourselves.
We understand that not all glass is the same, so we tailor our packaging techniques based on the type and quantity of products you order. This ensures maximum protection for every shipment.
Quartz (fused silica) circular sight glasses excel in high-temperature environments due to their superior clarity and resilience to thermal shock. Their low thermal expansion makes them well suited for use in furnaces, boilers, and reactors, where maintaining visibility is critical. These glasses withstand rapid temperature changes, making them reliable for monitoring processes in demanding industrial settings. The circular design ensures easy installation and clear, unobstructed viewing, enhancing safety and operational efficiency.
Quartz sight glass — Technical information
Physical properties
| Property | Testing method | Obtained value |
|---|---|---|
| Thermal expansion coefficient | ISO 7991 | 6.2 × 10⁻⁷ ºK |
| Density at 25ºC | SN 7005 13 | 2.20 g/cm³ |
| Refractive index (λ = 587.6 nm) nd | — | 1.425 |
| Maximum annealing temperature | ISO 7884-8 | 1500 ºC |
| Short-term maximum temperature | ISO 7884-7 | 1450 ºC |
| Thermal shock resistance | ISO 7884 | 500 K |
| Young's modulus | — | 68.0 MPa |
| Poisson constant | — | 0.17 |
| Thermal conductivity 20ºC – 100ºC λ | — | 0.003 CAL |
| Photoelastic constant | DIN 52314 | (4.00 × 10⁻⁶) (mm²/N) |
| Specific electrical resistance 10⁸ Ωcm | DIN 52326 | 250 ºC |
| Dimensional tolerances diameter | DIN 8902 | PASS |
Optical properties
| Property | Testing method | Obtained value |
|---|---|---|
| Bubble on glass | DIN 7080 | PASS |
| Marks on glass | DIN 7080 | PASS |
| Chamfer tolerance | DIN 7080 | PASS |
| Viscous knots | DIN 7080 | No visible |
| Glass inclusions | DIN 7080 | Less than 0.2 mm |
Quartz sight glass — Main uses and applications
Applications in ovens
Quartz sight glasses are essential in high-temperature ovens where visibility into the oven chamber is crucial for monitoring processes. They are used to observe internal conditions without compromising safety or performance. Quartz's high thermal resistance ensures durability under extreme temperatures, allowing operators to view the state of the materials being processed without opening the oven door. This capability is vital in industries like ceramics and glass manufacturing, where precise temperature control and visual monitoring are necessary for quality assurance.
Applications in burners
In burners, quartz sight glasses provide a clear view of the combustion process. They are used to observe the flame and ensure proper combustion conditions. Quartz is highly resistant to thermal shock and chemical exposure, making it ideal for environments where high temperatures and corrosive gases are present. This allows for real-time monitoring and adjustments to maintain optimal burner performance in industrial heating and power generation.
Processes above 500°C
Quartz sight glasses are designed to withstand environments where temperatures exceed 500°C. They provide a transparent view into high-temperature processes such as metal forging or high-temperature reactors. Their ability to endure extreme heat without deforming or degrading makes them indispensable where precise temperature monitoring and control are required.
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