Circular sight glass fitting type 321 DIN 28121 PN 10/25 for flange mounting

Borosilicate glass 3.3 is one of the most commonly used and well-known types of heat resistant glass. Its high silica content and significant boron oxide doping make it exceptionally stable. The material can be milled, drilled, ground, and toughened without losing its structural integrity. These characteristics, combined with its borosilicate glass strength, make it suitable for both industrial and scientific uses. This type of boro glass performs reliably at elevated temperatures and is thermally stable up to 450 °C under continuous use. Its borosilicate glass temperature stability is a primary reason why it is frequently selected for laboratory setups and chemical reactors. Additionally, borosilicate glass 3.3 maintains excellent mechanical strength even in low-temperature conditions, with operational capability down to -196 °C, making it compatible with cryogenic substances like liquid nitrogen. For optimal safety, the temperature difference during thawing should not exceed 100 K; typically, operation down to -70 °C is recommended. Thanks to its outstanding chemical resistance, this borosilicate glassware is impervious to water, acids, alkalis, and most organic solvents. As such, it is extensively used in pharmaceutical manufacturing, scientific research, and chemical processing plants. The borosilicate glass properties of type 3.3 also make it a material of choice for borosilicate glass dishes, beakers, flasks, and other laboratory vessels. Suprax 8488, Pyrex, Boronorm & Borofloat Other types of borosilicate glass, such as Suprax 8488, Pyrex, and Boronorm, offer comparable borosilicate glass hardness and resistance to chemical and thermal stresses. Suprax 8488 is known for its consistency and is often used in technical lighting and optical applications. Pyrex, a widely recognized brand name, is commonly found in consumer borosilicate glass products like cookware and bakeware. These borosilicate glass dishes resist staining, cracking, and thermal deformation, making them ideal for use in ovens and microwave environments. Borofloat is another premium borosilicate glass variant designed for optical, display, and semiconductor applications. Its exceptionally smooth surface and excellent flatness, combined with its inherent borosilicate glass strength, make it indispensable in high-tech industries. Whether used in analytical instruments or microelectronics, Borofloat ensures consistent performance under stress. Applications of borosilicate glass The variety of borosilicate glass applications is as vast as its properties. It is widely used in: Laboratory borosilicate glassware (beakers, test tubes, measuring cylinders) Domestic borosilicate glass products (bakeware, cookware, coffee carafes) Pharmaceutical containers (vials, ampoules) Chemical processing equipment (reactors, pipelines) Optical components (lenses, filters) High-intensity lighting systems (projector lamps, automotive bulbs) Solar energy systems (glass tubing, photovoltaic module covers) Display technology (substrates for TFT and OLED displays) The heat resistance of glass in these applications is crucial for maintaining dimensional stability and ensuring longevity. For instance, borosilicate glass dishes used in kitchens can transition directly from freezers to ovens without risk of breakage due to the material’s thermal shock resistance. Why choose borosilicate glass? To summarize, borosilicate glass combines chemical inertness, high mechanical strength, and remarkable temperature resistance, making it one of the most versatile materials available. Its hardness, clarity, and processability further enhance its desirability across numerous industries. Whether you are selecting materials for a high-performance optical lens, a laboratory flask, or a heat-resistant baking dish, borosilicate glass delivers outstanding performance. We supply a full range of borosilicate glassware and custom borosilicate glass products tailored to your specific needs. With several types of borosilicate glass available, including borosilicate glass 3.3, Suprax, Borofloat, and Pyrex, our product line meets the highest standards in modern engineering and design. Composition SiO2  80 % B2O3  13 % Na2O  4 % Al2O3  2 % K2O  1 %   Standard thicknesses and tolerances Thickness Tolerance Thickness Tolerance 0,70 mm ±0,1 7,5 mm ±0,3 1,10 mm ±0,1 8,0 mm ±0,3 1,75 mm ±0,2 9,0 mm ±0,3 2,00 mm ±0,2 13,0 mm ±0,5 2,25 mm ±0,2 15,0 mm ±0,5 2,75 mm ±0,2 16,0 mm ±0,5 3,30 mm ±0,2 17,0 mm ±0,5 5,00 mm ±0,2 18,0 mm ±0,5 5,50 mm ±0,2 19,0 mm ±0,5 6,50 mm ±0,2 21,0 mm ±0,7   Properties: Density (@ 20 °C) 2 230 kg/m3 Bending strength 160 N/mm2 Surface compressive stress 100 N/mm2 Young’s modulus  64 GPa Poisson’s ratio 0,2 Hardness 5.5 Mohs, (470 Knopp, 580 Vickers) Thermal conductivity 1,2 W/(m K) Specific Heat 0,83 kJ/(kg K) Coefficient of linear expansion 3,3 ±0,1 * 10 -6 °C Index of refraction (@ 380 - 780 nm) 1,48  Softening point 815 °C Annealing Point 560 °C Max. working temperature: Non-tempered glass    - long term 450 °C  - temporary(< 10h) 500 °C Tempered glass    - long term 280 °C  - temporary(< 10h) 500 °C   Chemical properties: Hydrolytic Resistance   Acc.  ISO 719 (w 98 °C): class HGB 1    Acc.  ISO 720 (w 121 °C): class HGA 1  Alkali resistance   Acc. DIN 52 322 (ISO 695): class A2 Acid resistance   Acc. DIN 12 116: class 1 Electrical properties Volume resistance    at 25°C = 6.6 x 1013 Ω cm    at 300°C = 1.4 x 106 Ω cm Dielectric properties Electric Volume Resistivity         8,6 x 1013 Ωcm (at   25 °C)   1.4 x 106   Ωcm (at 300 °C) Dielectric dissipation fraction   38  10-4 (at 1 MHz, 20 °C) Dielectric constant εr   4.6 (at 1 MHz, 20 °C)   Optical properties Index of Refraction Spectral Transmission    λ = 587,6 nm nD = 1,4724    λ = 480,0 nm nF = 1,4782    λ = 546,0 nm nE = 1,4740    λ = 644,0 nm nC = 1,4701    Borosilicate glass 4.3 SiO2  78 % B2O3  10% Na2O  7 % Al2O3  3% ZrO2  2 %   Properties: Density (@ 25  °C) 2 280 kg/m3 Flexural strength 25 MPa Modulus of elasticity (Young’s) 67 GPa Poisson’s ratio 0,20 Thermal conductivity (@ 90 °C) 1,2 W/(m K) Specific heat 0,83 kJ/(kg K) Coefficient of linear expansion  (@ 20 °C - 300 °C) 4,3  * 10 -6 °C Index of Refraction (λ=587,6 nm) 1,484  Softening point 810 °C Annealing point 580 °C Glass temperature for density dPas 1013,0    560 °C10 7,6    800°C10 4,0   1200°C Working temperature:  - maximum 500 °C  - in a heavy duty conditions 280 °C   Chemical properties   Hydrolytic Resistance   Acc.   ISO 719 (@ 98 °C): class HGB 1    Acc.   ISO 720 (@ 121 °C): class HGA 1  Alkali resistance   Acc. DIN 52 322 (acc. ISO 695): class A2 Acid resistance   Acc. DIN 1776: class 1 Electrical properties Volume resistance    @ 25°C = 6.6 x 1013 Ω cm    @ 300°C = 1.4 x 106 Ω cm Dielectric properties @ 25° C and 1 MHz:    Dielectric constant εr=4,6    Dielectric loss factor tgδ =1,4x10-2   Optical properties Index of Refraction Spectral Transmission    λ = 587,6 nm nD = 1,4816    λ = 480,0 nm nF = 1,4869    λ = 546,0 nm nE = 1,4831    λ = 644,0 nm nC = 1,4802      While every attempt has been made to verify the source of the information, no responsibility is accepted for accuracy of data. In this text you will learn about borosilicate glass: properties, strength, thermal and chemical resistance, types, and applications in laboratory, industrial, optical, and domestic environments. Properties and applications of borosilicate glass Borosilicate glass is a specialized type of glass that contains significant amounts of silica (SiO₂) and boron trioxide (B₂O₃), making it highly resistant to thermal shock and chemical corrosion. Known for its durability, clarity, and stability under temperature fluctuations, borosilicate glass is widely used in laboratory, industrial, and domestic applications. Often referred to as boro glass, this material exhibits unique performance characteristics that set it apart from conventional soda-lime glass. One of the key properties of borosilicate glass is its exceptional resistance to temperature changes. This heat resistant glass can withstand both extremely high and low temperatures, making it suitable for demanding environments. The borosilicate glass temperature resistance allows it to endure up to 450 °C during long-term use and down to -196 °C when in contact with substances like liquid nitrogen. These attributes are a result of its low coefficient of thermal expansion, which ensures the glass does not crack or deform when exposed to rapid temperature changes. Another significant feature is the borosilicate glass strength and durability under mechanical and thermal stress. The typical hardness of borosilicate glass is rated at 5.5 on the Mohs scale, with corresponding values of 470 on the Knoop scale and 580 on the Vickers hardness test. These measures confirm the high borosilicate glass hardness, making it ideal for situations that demand both precision and resilience. The versatility of borosilicate glass arises from the ability to modify its chemical composition by incorporating various metal oxides. These variations result in a broad range of borosilicate glass products, each tailored for specific applications. The boron oxide content in the glass batch—i.e., the mix of raw materials used in the production process—plays a crucial role in defining not only the borosilicate glass properties, but also the behavior of the molten glass during manufacturing. At our facility, we offer several types of borosilicate glass, including: Borosilicate glass 3.3 (DIN 7080) Borosilicate glass 4.3 Suprax 8488 Pyrex Boronorm Borofloat Each of these borosilicate glass types features unique compositions and is suited for various borosilicate glass applications, from laboratory glassware and cookware to high-performance optics and chemical equipment. To work in an environment of steam and hydrostatic applications we offer borosilicate glass 4.3. Resistance to chemicals and thermal expansion permit the use of a high level of hardening, so that the glass are characterized by high resistance to thermal shock. Is suitable for operation at low temperatures. Can withstand the temperature to about -196 °C (is suitable for use in contact with liquid nitrogen). During thawing ensure that the temperature difference does not exceed 100 K. In general is recommended for use down to -70 °C.

Cross-sectiondrawing Dimensions Dimensions: Size     3 4 5 6 7 8 9 10 11 12 13 Nominal width  DN   50 80 100 125 150 200 250 300 350 400 500 Glass Ø  D [mm]    100 125 150 175 200 250 300 upon request Clear view  d1 [mm]    80 100 125 150 175 225 280 Wiping circle Ø  d2 [mm]    75 95 120 145 170 220 275 Glass thickness  S [mm]  Operating pressure max. PS [barü] Height  H [mm]                    116 15 8 5 4 3 2 / / 111 20 12 8 5 5 4 2 1 106 25 20 12 8 8 5 4 2 121 30 25⁴ 20 12 12 8 5 3 116 35 / 25⁴  21 15 11 7 4 111 40 / / 25⁴  20 14 9 6 106 45 / / / 25⁴  18⁴  11 7 111 55 ³   3) 55 mm on request4) higher pressures on request The sight glass wipers of type SGW are designed for the on-demand manual cleaning of glass plates in round sight glass fittings. They are suitable for applications under pressure and can also be easily retrofitted into existing sight glass fittings. Made of high-quality stainless steel, the wipers also meet the requirements in the food and drinking water sector. Various materials are available for the wiper blade: PTFE, silicone, or EPDM. The sight glass wipers are particularly effective in combination with the spray device SVI or SVIII.

Cover flange Glass cushion Sight glass PTFE coated encased corrugated ring gasket Base flange Screws Our round sight glasses type 321A are screwed onto flanges according to ASME B16.5 to allow for observation or illumination of the container interior. ACI sight glasses of type 321A are constructed according to DIN 28121 for operating pressures up to 20 barg. Between two high-quality stainless steel flanges and a media-side PTFE-coated corrugated gasket, a sight glass made of chemically highly resistant MAXOS® borosilicate glass DIN7080 is clamped. Since this gasket is in force shunt, the flange parts of the sight glass lie directly on top of each other and thus protect the glass plate as effectively as possible. The type 321A is delivered pre-assembled from the factory and can be screwed directly onto a flange according to ASME B16.5 without any additional effort. Should the unlikely event occur that the glass is damaged during operation, the entire fitting can be replaced with little effort. Our sight glasses of type 321A are made from high-quality stainless steels 1.4571 (316Ti) or 1.4404 (316L). As glass material, the industrially proven MAXOS® borosilicate glass according to DIN 7080 is used. The sealing in force shunt prevents settling of the gaskets, so that re-tightening of the tension screws on site is no longer necessary. The PTFE-coated gasket makes the sight glass type 321A suitable for food, acids, alkalis, and most aggressive chemicals. If the borosilicate glass DIN 7080 does not meet your requirements, or if the process conditions themselves pose a problem for the highly resistant borosilicate glass, a custom-fitted mica protection disc offers additional protection against temperature and steam. FEP or Halar® coatings additionally protect the borosilicate glass from aggressive chemicals or alkalis. Like other sight glass fittings, the type 321A can be equipped with a wiper type SGW, spraying devices SVII, or lights upon request. Cross-sectiondrawing Dimensions NPS 2“ 3“ 4“ 5“ 6“ 8“ Di [mm] 65 80 100 125 125 150 H [mm] 41 50 59 66 66 66 Da [mm] According to ASME B 16.5 L [mm] K [mm] Weight [kg] 3.8 8 13.5 17.4 23 36.7  

Cover flange Glass cushion Sight glass Gasket Base flange Screws The container sight glass type 322 for high-pressure applications is a solid fitting based on the design principles set forth in the industrial standard DIN 28121. Through the significantly reinforced flange and the use of glass plates beyond the standard dimensions of DIN 7080, it is possible for us with type 322 to achieve operating pressures of up to 160 barg. The tensioning of the glass occurs similarly to our proven type 322 through pre-tensioning screws. This ensures that the fitting only needs to be properly attached to the carrier flange in your system to achieve the necessary sealing. An execution for elevated temperatures is also feasible through the use of appropriate seals and glass materials. Due to the high operating pressure, the installation of wipers and spraying devices is unfortunately not possible with type 322. Lighting based on LED lighting elements is available from us. Should the borosilicate glass not meet your requirements similar to DIN 7080, or if the process conditions themselves pose a problem for the highly resistant borosilicate glass, a mica protective disc specifically adapted for the fitting offers additional protection against temperature and steam. FEP or Halar® coatings additionally protect the borosilicate glassagainst aggressive chemicals or caustics. Cross-sectiondrawing Dimensions DN 40 50 80 100 Di [mm] 40 50 80 100 H (PN 40) [mm] 84 84 84 104 H (PN 63) [mm] 84 84 84 104 H (PN 100) [mm] 84 104 104 104 H (PN 160) [mm] 94 104 104 121 Da [mm] According to DIN EN 1092-1 L [mm] K [mm]  

Cover flange Glass cushion Sight glass Graphite composite gasket Base flange Screws The ACI sight glass type 323 is a variation of type 321, designed for an expanded range of applications, especially at higher temperatures. They serve to observe and illuminate the interior of sealed containers (container, boilers, tanks, silos, etc.). The PTFE-coated corrugated ring gaskets typically used in type 321 are no longer reliably usable above a temperature of 200 °C. To eliminate this disadvantage, we use high-quality graphite composite seals in type 323, so that the operating range of the borosilicate glass plates according to DIN 7080 can be fully utilized up to 280 °C, or even 320 °C with a mica disc. Even at temperatures above the limits of DIN 7080, type 323 can be used without problems with untempered borosilicate glass plates up to 400 °C. For higher temperatures, please inquire. With the sealing in the force shunt, type 323 offers you the same advantages as our proven type 321. Here, too, the glass plate is best protected over the entire circumference, and the fitting can be easily installed or exchanged as a single component. The fitting is completely assembled at the factory and can, upon request, be tested for pressure resistance and tightness, so you can rely 100% on our quality. Like type 321, type 323 can also be supplied with LED lighting upon request. Cross-sectiondrawing Dimensions DN 40 50 80 100 125 150 200 Di [mm]PN 10 48 65 80 100 125 125 150 H [mm]PN 10 36 38 46 46 54 54 54 Da [mm]PN 10 150 165 200 220 250 285 340 L [mm]PN 10 18 18 18 18 18 22 22 K [mm]PN 10 110 125 160 180 210 240 295 Weight [kg]PN 10 3,8 4,6 8,2 9,3 13,8 19,5 28,7 H [mm]PN 25 38 41 50 59 66 66 66 Da [mm]PN 25 150 165 200 235 270 300 360 L [mm]PN 25 18 18 18 22 26 26 26 K [mm]PN 25 110 125 160 190 220 250 310 Weight [kg]PN 25 4 5 8,9 14 20 26,9 39,3