Product Overview
This product is commonly searched as soda-lime reflex gauge glass, soda lime sight glass, reflex sight glass, reflex level gauge glass, disc sight glass, and level indicator glass. Reflex level gauges use a prismatic glass surface so the wetted zone appears dark and the vapor zone appears bright, which makes liquid level easier to read.
Typical Applications
Soda-lime reflex gauge glass is used in process vessels, tanks, and pipeline level indicators where visual inspection must be ensured under pressure but the service remains within low thermal and chemical load conditions. Published DIN 8902 guidance gives an operating temperature of 150 °C.
Material and Specification
DIN 8902 soda-lime glass data states a coefficient of expansion of 9.5 × 10⁻⁶ K⁻¹ at 20 °C / 300 °C, thermal shock resistance of 150 °C, hydrolytic resistance class 4, acid resistance class 1, and alkali resistance class 2. The same specification describes the glass as thermally toughened, ground, and polished.
Technical Parameters
| Item | Specification |
|---|---|
| Material | Tempered soda-lime glass |
| Product type | Soda-lime reflex gauge glass / reflex sight glass / disc sight glass |
| Standard | DIN 8902 |
| Operating temperature | Up to 150 °C |
| Pressure | Depends on diameter and thickness |
| Coefficient of expansion | 9.5 × 10⁻⁶ K⁻¹ |
| Thermal shock resistance | 150 °C |
| Water resistance | DIN ISO 719/720, hydrolysis class 4 |
| Acid resistance | DIN 12116, acid class 1 |
| Alkali resistance | DIN 52332, alkali class 2 |
| Surface finish | Ground and polished |
| Heat treatment | Thermally toughened |
Common Sizes
The standard DIN 8902 round sight-glass sizes below are published with admissible pressure values.
| Diameter × Thickness (mm) | Viewing Diameter (mm) | Max. Pressure (bar) |
|---|---|---|
| 45 × 10 | 32 | 40 |
| 63 × 10 | 48 | 16 |
| 80 × 12 | 65 | 16 |
| 100 × 15 | 80 | 16 |
| 125 × 15 | 100 | 10 |
| 125 × 20 | 100 | 16 |
| 150 × 15 | 125 | 8 |
| 150 × 20 | 125 | 10 |
| 150 × 25 | 125 | 16 |
| 175 × 20 | 150 | 10 |
| 175 × 25 | 150 | 16 |
| 200 × 20 | 175 | 8 |
| 200 × 25 | 175 | 10 |
| 250 × 20 | 225 | 4 |
| 250 × 25 | 225 | 8 |
Dimensional Tolerances and Quality Control
Published DIN 8902 tolerances are ±0.5 mm for diameters up to 125 mm, ±0.8 mm for diameters from 125 to 200 mm, and ±1.0 mm above 200 mm. For thickness, the tolerance is ±0.50 mm from 10 to 20 mm and ±0.80 mm above 20 mm. Permissible material defects include round bubbles up to 2 mm maximum diameter, while tapered bubbles are not permitted.
Advantages
Soda-lime reflex gauge glass is a practical choice for low-temperature level indication when cost control and clear reading are important. It is suited to standard reflex gauge service where the process conditions stay within the DIN 8902 limits and the operator needs a fast, high-contrast level reading.
