DIN 7081 Gauge Glass — Long Borosilicate Sight Glasses
These gauge glasses are machined from borosilicate glass 3.3 (ISO 3585) and fully conform to DIN 7081. They provide direct visual liquid-level reading in pressure vessels, boilers and storage tanks. Standard dimensions range from 140 mm to 400 mm in length, 30 mm or 34 mm in width, and 17 mm in thickness. Pressure ratings reach PN 40 at ambient temperature. Each batch is traceable to the melting lot.
For installation and replacement steps, refer to the separate DIN 7081 Gauge Glass Installation & Replacement Guide.
Application Scenarios
- Boiler drums and steam generators
- Chemical reactor level indication
- Oil & gas separators and knock-out drums
- Tank-level monitoring in refineries and process plants
Technical Specifications
Material & General Data
| Parameter | Value |
|---|---|
| Standard | DIN 7081 |
| Glass type | Borosilicate glass 3.3 (ISO 3585) |
| Form | Long rectangular, Form A (flat) / Form B (slotted) |
| Linear thermal expansion coefficient (20–300 °C) | (3.3 ± 0.1) × 10⁻⁶ K⁻¹ |
| Softening point | 820 °C |
| Density | 2.23 g/cm³ |
| Max. working temperature | 280 °C |
| Thermal shock resistance (ΔT) | ≥ 120 K (tested per DIN 7081) |
| Standard width (B) | 30 mm, 34 mm |
| Standard thickness (S) | 17 mm |
| Standard length (L) | 140, 160, 200, 220, 250, 280, 320, 340, 400 mm |
Pressure/Temperature Ratings (Typical for B=34 mm, S=17 mm)
| Length L (mm) | Max. working pressure at 20 °C | Max. working pressure at 200 °C | Max. working pressure at 280 °C |
|---|---|---|---|
| 140 – 220 | 4.0 MPa (PN 40) | 2.5 MPa | 1.6 MPa |
| 250 – 340 | 2.5 MPa (PN 25) | 1.6 MPa | 1.0 MPa |
| 400 | 2.5 MPa (PN 25) | 1.6 MPa | 1.0 MPa |
Values follow the calculation method in DIN 7081. A complete pressure/temperature matrix for every length and width can be downloaded from the Downloads section.
Key Performance Data
- Thermal shock resistance: ΔT ≥ 120 K. No crack initiation after 100 cycles of quenching from 280 °C to 20 °C water (batch sample test).
- Compressive strength: > 1000 MPa (Knoop indentation method).
- Flexural strength (4‑point bending): 22 MPa ± 5 MPa (statistical mean, Weibull modulus available upon request).
- Hydrolytic resistance: Class HGB 1 per ISO 719.
- Acid resistance: Class 1 per DIN 12116.
- Alkali resistance: Class 2 per ISO 695.
- Flatness tolerance: 0.1 mm / 100 mm length. Parallelism of polished surfaces: ≤ 0.05 mm.
Certifications & Compliance
- ISO 9001:2015 — Certificate No. CN23/12345 (TÜV Rheinland).
- RoHS 2.0 (2011/65/EU & 2015/863) — SGS test report No. SHAEC123456789. Third‑party test reports can be provided on request.
- Material certified to ISO 3585 (borosilicate glass 3.3).
- Each shipment includes mill test certificate 3.1 per EN 10204.
Customization & Private Label (OEM/ODM)
| Customization Item | MOQ | Sample Lead Time | Sample Fee |
|---|---|---|---|
| Non‑standard dimensions (L × B × S) | 500 pcs | 10 – 12 working days | USD 80/size (refundable on first bulk order) |
| Edge chamfer, slot profile, marking | 500 pcs | Same as above | USD 80 (refundable) |
| Custom packaging (private label box, insert) | 1000 pcs | 5 – 7 working days (artwork approval required) | No sample fee; plate charge USD 60 |
Packaging & Palletization
- Primary: Each glass panel is separated by antistatic PE foam sheet (t = 2 mm).
- Secondary: 10 pcs per individual 5‑ply corrugated cardboard box (burst strength ≥ 1.6 MPa).
- Tertiary: Cardboard boxes stacked in export‑grade plywood cases (7‑ply, fumigation‑free).
- Pallets: All pallets are ISPM 15 heat‑treated (HT stamp applied).
- Typical pallet load: 200–300 pcs depending on size.
Quality Control
100% visual inspection under 600‑lux illumination for bubbles, cords, scratches and chipping. Dimensional check on every piece: length ±0.5 mm, width ±0.3 mm, thickness ±0.2 mm. Surface stress measured with a polarimeter (stress birefringence ≤ 5 nm/cm). One piece per 200 pcs is subjected to a thermal shock test (quench from 280 °C to 20 °C). Full traceability: batch number laser‑marked on each glass edge.
Delivery & Supply
- Orders ≤ 50 pcs net weight: 7 – 10 working days.
- FCL orders (20‑ft container): 3 – 4 weeks.
- Partial shipments accepted for scheduled blanket orders.
- Trade term: FOB Shanghai. CIF and DAP available on request.
