In high-demand industrial applications, equipment durability and operational safety are non-negotiable. One critical yet often overlooked component that plays a pivotal role in process observation is the sight glass. Specifically, tempered sight glasses have become essential in industries such as chemical processing, oil and gas, food and beverage, pharmaceuticals, and power generation.
A tempered sight glass is a type of viewing window made from heat-treated glass designed to resist thermal stress, mechanical impact, and chemical corrosion. These sight glasses are commonly installed in pipelines, tanks, and pressurized vessels to provide real-time visual inspection of fluid flow, level, and clarity—without compromising system integrity.
Tempered borosilicate flow
Tempered borosilicate cylinders, utilized in 360° view sight flow indicators, combine high chemical and thermal resistance with the strength needed for demanding industrial applications.
Borosilicate glass, known for its low coefficient of thermal expansion, allows these cylinders to withstand temperature variations and aggressive chemicals without compromising integrity. The tempering process further enhances their durability, making them ideal for observing fluid dynamics in real time from any angle, a crucial feature for processes involving hazardous or high-temperature fluids.
These indicators are indispensable in chemical processing, pharmaceuticals, and petrochemical industries, where continuous monitoring of fluid flow, color, and clarity is essential. The 360° visibility offered by these cylinders ensures comprehensive monitoring, facilitating improved process control and safety.
| Property | Testing method | Obtained value |
|---|---|---|
| Thermic dilatation coefficient | ISO 7991 | 3.3 × 10⁻⁶ |
| Density at 25°C | SN 7005 13 | 2.23 g/cm³ |
| Refractive index (λ = 587.6 nm) nd | — | 1.472 |
| Maximum annealing temperature | ISO 7884-8 | 1040 ºF |
| Short-term maximum temperature | ISO 7884-7 | 932 ºF |
| Thermal shock resistance | ISO 7884-4 | 5.67 ºF |
| Young's modulus | — | 63 150 MPa |
| Poisson constant | — | 0.2 |
| Thermal conductivity 20°C – 100°C λ | — | (1.2) (w·m⁻¹)(K⁻¹) |
| Photoelastic constant | DIN 52314 | (4.00 × 10⁻⁶) (mm²/N) |
| Specific electrical resistance 10⁸ Ωcm | DIN 52326 | 482 ºF |
| Dimensional tolerance diameter | DIN 7080 | PASS |
| Property | Testing method | Obtained value |
|---|---|---|
| Hydrolytic resistance | ISO 719 | HGB 1 |
| Acid resistance | ISO 1776 | CLASS S1 |
| Alkaline resistance | ISO 695 | CLASS 2 |
| Chemical composition SiO₂ | — | Minimum content 80% |
| Chemical composition B₂O₃ | — | Minimum content 13% |
| Chemical composition Na₂O + K₂O | — | Minimum content 4.5% |
Tempered soda lime
Tempered soda lime circular sight glasses are designed for durability and impact resistance, widely used in less extreme industrial environments.
Soda lime glass, after undergoing a tempering process, significantly increases its strength and resistance to physical shock, making it a cost-effective option for general applications. These glasses are particularly valued for their clear visibility and robustness, suitable for various applications including water treatment facilities, low-pressure vessels, and environmental monitoring equipment.
Their circular shape allows for versatile installation and easy viewing, supporting safe and efficient process monitoring. While not as resistant to high temperatures and chemicals as quartz sight glasses, they offer a reliable and economical solution for a broad range of industrial needs.
| Property | Testing method | Obtained value |
|---|---|---|
| Thermic dilatation coefficient | ISO 7991 | 8.72 × 10⁻⁷ ºK |
| Density at 25°C | SN 7005 13 | 2.49 g/cm³ |
| Refractive index (λ = 587.6 nm) nd | — | 1.472 |
| Maximum annealing temperature | ISO 7884-8 | 1040 ºF |
| Short-term maximum temperature | ISO 7884-7 | 302 ºF |
| Thermal shock resistance | ISO 7884-3 | 33.67 ºF |
| Young's modulus | — | 63 150 MPa |
| Poisson constant | — | 0.2 |
| Thermal conductivity 20°C – 100°C λ | — | (1.2) (w·m⁻¹)(K⁻¹) |
| Photoelastic constant | DIN 52314 | (4.00 × 10⁻⁶) (mm²/N) |
| Specific electrical resistance 10⁸ Ωcm | DIN 52326 | 482 ºF |
| Dimensional tolerance diameter | DIN 7080 | PASS |
| Property | Testing method | Obtained value |
|---|---|---|
| Bubbles in glass | DIN 7080 | PASS |
| Chamfer tolerance | DIN 7080 | PASS |
| Viscous knots | DIN 7080 | PASS |
| Glass inclusions | DIN 7080 | Less than 0.2 mm |
Tempered borosilicate
Manufactured from 3.3 borosilicate glass, these scopes are used in various applications where good chemical resistance and a low coefficient of thermal expansion are required. Poor chemical resistance can cause the glass to react and release unwanted substances in the process, such as arsenic which forms when non-borosilicate glass reacts with water.
Special scope dimensions are available upon request, where the minimum diameter is 2/5″ and the maximum diameter is 13.78″. Thickness can be manufactured from a minimum of 1/8″ and a maximum of 1 3/8″.
| Property | Testing method | Obtained value |
|---|---|---|
| Thermic dilatation coefficient | ISO 7991 | 3.3 × 10⁻⁶ |
| Density at 25°C | SN 7005 13 | 2.23 g/cm³ |
| Refractive index (λ = 587.6 nm) nd | — | 1.472 |
| Maximum annealing temperature | ISO 7884-8 | 1040 ºF |
| Short-term maximum temperature | ISO 7884-7 | 932 ºF |
| Thermal shock resistance | ISO 7884-4 | 5.67 ºF |
| Young's modulus | — | 63 150 MPa |
| Poisson constant | — | 0.2 |
| Thermal conductivity 20°C – 100°C λ | — | (1.2) (w·m⁻¹)(K⁻¹) |
| Photoelastic constant | DIN 52314 | (4.00 × 10⁻⁶) (mm²/N) |
| Specific electrical resistance 10⁸ Ωcm | DIN 52326 | 482 ºF |
| Dimensional tolerance diameter | DIN 7080 | PASS |
| Property | Testing method | Obtained value |
|---|---|---|
| Hydrolytic resistance | ISO 719 | HGB 1 |
| Acid resistance | ISO 1776 | CLASS S1 |
| Alkaline resistance | ISO 695 | CLASS 2 |
| Chemical composition SiO₂ | — | Minimum content 80% |
| Chemical composition B₂O₃ | — | Minimum content 13% |
| Chemical composition Na₂O + K₂O | — | Minimum content 4.5% |
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