Long borosilicate glass according to and similar to DIN 7081
Product specification: Long sight glass panels
Material: Borosilicate glass thermally toughened (hardened)
Removal rates and further information on the glass can be found in our info data sheet and in our brochure.
MAXOS® borosilicate glass safety sight glasses are required wherever visual inspection of processes in containers must be ensured under pressure, thermal and chemical stress.
The high level of safety is achieved by using a special borosilicate glass with good chemical resistance, extraordinary purity and homogeneity. In combination with the low thermal expansion typical of this borosilicate glass, thermal tempering (hardening) leads to a particularly high thermal shock resistance.
Production and quality checks in the process sequence guarantee the property values of the glasses and the close dimensional tolerances. With these outstanding safety properties, MAXOS® safety sight glasses can be used for extreme conditions.
Operating conditions:
The pressure-temperature assignment in the INFO data sheet must be observed! The following table is for orientation purposes only.
Calculation of the pressure resistance: TOOL - Glass consultant borosilicate glass DIN 7081
| Operating method: | Max. operating pressure: | Max. operating temperature: |
| Unprotected reflex and transparent sight glasses with saturated steam or hot water pressure | 35 bar / 500 psi | 243 °C / 470 °F |
| Mica-protected transparent sight glasses with saturated steam or hot water pressure | 103 bar / 1500 psi | 320 °C / 608 °F |
| Reflex sight glasses when used without steam and without technically significant glass attack | 280 bar / 4000 psi | 38 °C / 100 °F |
| For media without technically significant glass attack for transparent sight glasses | 345 bar / 5000 psi | 38 °C / 100 °F |
| High-pressure transparent sight glasses in special fittings | 414 bar / 6000 psi | 38 °C / 100 °F |
Chemical resistance:
Water resistance DIN ISO 719/720: Hydrolysis class 1
Acid resistance DIN 12116: Acid class 1
Alkali resistance DIN 52332: Alkali class 2
Technical information:
Coefficient of expansion at 20 °C / 300 °C (68 °F / 572 °F) : 4.1 x 10–6 K–¹
Young's modulus: 67 x 103 N/mm²
Thermal conductivity at 90 °C / 194 °F: 1.2 W/(m·K)
Stress-optical coefficient K: 3.2 x 10–6 mm²/N
Thermal shock resistance: 265 °C / 509 °F
Permissible material defects:
Round bubbles enclosed in the glass may have a maximum diameter of 2 mm. Oval bubbles must not exceed the value (length + width)/2 = 2 mm. Pointed bubbles are not permitted.
Permissible bubble frequency
| bubble diameter. (d3) | Permissible bubble frequency | Permissible bubble frequency |
| ≤ 250 mm | > 250 mm | |
| d3 < 0,3 | 3 pieces per cm² visible surface | 3 pieces per cm² visible surface |
| 0,3 ≤ d3 ≤ 0,5 | 10 pieces per glass | 15 pieces per glass |
| 0,5 < d3 ≤ 1 | 4 pieces per glass | 6 pieces per glass |
| 1 < d3 ≤ 2 | 2 pieces per glass | 3 pieces per glass |
Dimensional tolerances:
The dimensional tolerances are in accordance with DIN 7081 for borosilicate glass sight glasses. The parallelism is ≤ 0.08 mm for standard sight glasses and ≤ 0.05 mm for high-pressure sight glasses.
Dimensional tolerances according to DIN 7081
Dimensional tolerances for longitudinal glass width 34 mm:
| Tolerance | |
| Length (95 ... 400 mm) | + 0 mm / – 1,5 mm |
| Wide (34 mm) | + 0,2 mm / – 0,8 mm |
| Thickness(17,5 mm) | + 0 mm / – 1,0 mm |
Dimensional tolerances for longitudinal glass width 30 mm:
| Length(115 ... 340 mm) | Tolerance |
| up to 250 mm | ± 0,8 mm |
| over 250 mm | ± 1,0 mm |
| Wide (30 mm) | + 0,5 mm / – 0,8 mm |
| Thickness(17,5 mm) | + 0 mm / – 1,0 mm |
