Round borosilicate glass according to and similar to DIN 7080
Product specification: Round sight glass plates
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:
Temperature:
- 280 °C / 536 °F long-term
- 300 °C / 572 °F short-term (<300 h)
- 320 °C / 608 °F with mica protected
Pressure: depending on diameter and thickness
Calculation of the pressure resistance:: TOOL - Glass consultant borosilicate glass DIN 7080
Technical informations:
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
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
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 |
| d3 < 0,3 | 3 pieces per cm² visible surface |
| 0,3 ≤ d3 ≤ 0,5 | 10 pieces per sight glass plate |
| 0,5 < d3 ≤ 1 | 4 pieces per sight glass plate |
| 1 < d3 ≤ 2 | 2 pieces per sight glass plate |
Dimensional tolerances:
The dimensional tolerances are in accordance with DIN 7080 for sightglass plates made of borosilicate glass.
Dimensional tolerances according to DIN 7080
| Diameter | | tolerance |
| up to 135 mm | ± 0,5 mm |
| 150 to 200 mm | ± 0,8 mm |
| over 200 mm | ± 1,0 mm |
| Thickness | |
| up to 20 mm | + 0,50 mm / – 0,25 mm |
| over 20 mm | + 0,80 mm / – 0,40 mm |
