What characterizes round borosilicate glass according to DIN 7080?
Sight glass plates made of borosilicate glass are thermally tempered and specifically designed for use in applications with high pressure as well as thermal and chemical stresses. They are characterized by high thermal shock resistance and chemical durability, and they are manufactured under strict production and quality controls.
Properties of Borosilicate glass according to and based on DIN 7080
Product specification: Circular sight glass plates
Material: Borosilicate glass thermally tempered (hardened) according to DIN 7080
Removal rates and further information on the glass can be found in our information data sheet and in our brochure.
MAXOS® Borosilicate glass according to DIN 7080: Safety sight glasses are required wherever visual inspection of processes in containers must be ensured under pressure, with thermal and chemical stress .
The high safety is achieved through a special borosilicate glass with good chemical resistance, extraordinary purity, and homogeneity. In combination with the characteristic low thermal expansion of this borosilicate glass, thermal tempering (hardening according to DIN 7080) leads to particularly high temperature cycling resistance.
Through production and quality inspections during the process flow, the property values of the glasses and the tight dimensional tolerances are guaranteed. With these excellent safety properties, MAXOS® safety sight glasses according to DIN 7080 can be used in extreme conditions.
Operating Conditions:
Temperature:
- 280 °C permanently
- 300 °C temporarily (<300 h)
- 320 °C mica protected
Pressure: depending on diameter and thickness
Calculation of pressure resistance: TOOL - Glass Advisor Borosilicate glass DIN 7080
Technical Information:
Coefficient of expansion at 20 °C/300 °C: 4.1 x 10– ⁶ K–¹
Modulus of elasticity: 67 x 103 N/mm²
Thermal conductivity at 90 °C: 1.2 W/(m·K)
Photoelastic coefficient K: 3.2 x 10– ⁶ mm²/N
Temperature cycling resistance: 265 °C
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:
Circular 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. Tapering bubbles are not permissible.
Permissible Bubble Frequency
| Bubble diameter d3 | | Permissible Bubble Frequency |
|---|---|
| d3 < 0.3 | 3 pieces per cm² of sight area |
| 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 based on DIN 7080 for sight glass 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 |
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