Clamp connection sight glass type 328 Clamp connection according to DIN 32676

Material: Base flange and cover flange: RSt 37-2, H II, C 22.8, P250GH, P265GH, 1.4306 (F304L), 1.4404 (F316L), 1.4462 Duplex (F51), 14539 (Alloy 904 L), 1.4541 (F321) , 1.4571 (F316Ti) or according to customer specifications Sight glass:  borosilicate glass acc. to DIN 7080 Soda-lime glass acc. to DIN 8902 Seal:  Klingersil or as desired Screws:  A4-70 Shape:  according to DIN 28120 Nominal size: DN25 - DN250 Nominal pressure:  PN 10/16  (depending on size and material composition) Temperature:  with soda lime glass up to max. 150 ° C with borosilicate glass up to max. 280 ° C  with borosilicate & mica shield up to 320 ° C Higher operating temperatures on request Options:  Optional versions are possible.   Special construction/options: With wiper blades SWI or SWII With spray nozzle SV1 Double glass Double Glass with heating element With LED or halogen lights, ATEX certification available With protective coating, variant B of DIN 28120 With O-Ring seal High Temperature Version with quartz window Impact protection plexiglass shield More special constructions available on request   DN Da Di h1 h2 s kg Nm 25 115 48 16 25 10 2,9 30 40 150 65 16 30 12 5,0 55 50 165 80 16 30 15 6,0 55 80 200 100 20 30 20 10,3 55 100 220 125 22 30 25 11,5 55 125 250 150 25 30 25 15,2 64 150 285 175 30 36 30 23,5 107 200[1] 340 225 35 36 30 30,7 125 250[1] (similar to DIN) 395 280 40 40 45 44,6 107   [1] PN 10 only   Use our 360° 3D view to get a perfect allround look at our product. Our round sight glasses type 320 are welded on or in a container wall to allow for observation or illumination of the inside of the container. A sight glass made of chemically highly resistant borosilicate glass DIN7080 is clamped between two high-quality stainless steel flanges and proven quality seals.  Beyond the definitions of DIN 28120, we also offer type 320 in special sizes of DN 250 and DN 300. These sizes, not specified in the standard, have also been constructed in accordance with DIN 28120.  Our sight glasses type 320 are made from high-quality stainless steel 1.4571 (316Ti), which our customers have appreciated for years. The glass material used is the tried-and-tested borosilicate glass according to DIN 7080 (or according to customer specifications).  The sealing of the fitting is done with flat seals tailored to your needs from a comprehensive range of materials. In addition to the common fiber seals, this also offers more demanding materials such as PTFE (Teflon®), NBR, novaphit® MST-XP, KlingerSil® C4400, and many other brand seals. If the maximum operating temperature of borosilicate glass DIN 7080 does not meet your requirements, or if the process conditions pose a problem even for the highly resistant borosilicate glass, a mica protection disk specially adapted for the fitting 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, type 320 can be equipped upon request with sight glass wiper type SGW and SWII, spray devices SVI, or lights.

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.

The method of sizing:   DiameterD [mm] Widths [mm] Pressure[bar] Notes 24 10 150 disc special size 30 12 150 disc special size 15 200 disc special size 31,6 12,75 150 disc special size   Aluminosilicate 33 14 150 disc special size 33,12 15,95   Aluminosilicate 34 17 200 disc special size   Aluminosilicate 35 7 25 disc special size 40 10 40 disc special size 12 50 disc special size 44 10 40 disc special size 12 50 disc special size 45 10 40 acc. DIN 7080 12 50 acc. DIN 7080 50 10 25 acc. DIN 7080 12 40 acc. DIN 7080 55 6,5 6 disc special size 10 25 disc special size 60 10 16 acc. DIN 7080 12 25 acc. DIN 7080 15 40 acc. DIN 7080 20 95 disc special size 63 8 8 disc special size 10 16 acc. DIN 7080 12 25 acc. DIN 7080 15 40 acc. DIN 7080 65 10 12 disc special size 15 40 disc special size 70 12 16 disc special size 15 25 disc special size 75 12 16 disc special size 80 10 10 disc special size 12 16 acc. DIN 7080 15 25 acc. DIN 7080 20 40 acc. DIN 7080 86 12 10 disc special size 90 10 8 disc special size 92 10 8 disc special size 94 12 10 disc special size 95 10 6 disc special size 15 16 disc special size 100 10 7 disc special size 12 10 disc special size 15 16 acc. DIN 7080 20 25 acc. DIN 7080 25 40 acc. DIN 7080 105 15 16 disc special size 110 12,5 10 disc special size 20 25 disc special size 113 15 10 disc special size 115 15 10 disc special size 120 10 4 disc special size 15 10 disc special size 18 16 disc special size 125 15 10 acc. DIN 7080 20 16 acc. DIN 7080 25 25 acc. DIN 7080 30 40 disc special size 130 15 10 disc special size 135 15 8 disc special size 25 25 acc. DIN 7080 140 15 8 disc special size 150 10 2 disc special size 15 8 disc special size 20 10 acc. DIN 7080 25 16 acc. DIN 7080 30 25 acc. DIN 7080 160 20 12 disc special size 170 15 5 disc special size 20 10 disc special size 175 20 10 acc. DIN 7080 25 16 acc. DIN 7080 30 25 acc. DIN 7080 200 20 8 acc. DIN 7080 25 10 acc. DIN 7080 30 16 acc. DIN 7080 210 25 10 disc special size 250 20 4 disc special size 25 8 acc. DIN 7080 30 10 acc. DIN 7080 265 30 8 acc. DIN 7080   Note: if in the column Notes otherwise stated, borosilicate glass "extra hard" is used Round sight glasses are delivered separately or in a set with gaskets and mica shield. If you can not find the size - please contact us. Tolerances Diameter (d1):d1 ≤ 125 mm125 mm < d1 ≤ 200 mm d1 > 200 mm  ± 0,5 mm± 0,8 mm± 1,0 mm     Thicknes (s):s ≤ 20 mm s > 20 mm  + 0,5 mm / -0,25 mm+ 0,8 mm / -0,40 mm  Flatness (e):d1 ≤ 100 mm100 mm < d1 ≤ 150 mm 150 mm < d1 ≤ 200 mmd1 > 200 mm 0,05 mm0,08 mm0,12 mm0,15 mm    Parallelity (p):d1 ≤ 100 mm100 mm < d1 ≤ 200 mm d1 > 200 mm 0,20 mm0,25 mm0,30 mm Calculation of the glass thickness s - theoretical minimum glass thicknes [mm] dm => (d1+d2)/2 => average sealing diameter [mm]d1 - glass and sealing outside diameter [mm]d2 - sealing inside diameter [mm]p - permisible presure [bar] δbB - min. value of surface comressive stress [N/mm2] S - safety factor        Our offer includes sight glasses made of various materials, depending on environmental conditions (temperature, pressure, aggressive media). The properties of various glass materials are described on page Types of materials in chapter Our offer/Technical glass. The basic types of materials used for the manufacture of sight glasses are: soda-lime glass - widely available, cheap, working temperature up to 280 °C,  borosilicate glass - particularly suitable for use in aggressive environments (acids, alkalis, water vapor), working temperature up to 350 °C, aluminosilicate glass -  working temperature up to 660 °C, glass-ceramics - thermal shock resistant, working temperature up to 750 °C, quartz glass - with a broad spectrum light transmittance (from ultraviolet to infrared), working temperature up to 1100 °C, sapphire products - working temperature up to 2000 °C. To improve the strength, the machined glass is subjected to toughening and annealing. In order to increase the resistance of sight glasses on the aggressiveness of the working environment and in the use of high temperatures and pressures, additional use of mica shield is recommended. Mica disc working as shields are described here.  If you need this solution - please contact us. Round sight glasses are delivered separately or in a set with gaskets. Gaskets for sight glasses are described here. We offer sight glasses manufactured by leading brands such as: Spectraglass, Klinger or Maxos, which guarantees high quality and stability of parameters.   Safety precautions when using sight glass discs: Whenever a sight glass assembly has been taken apart it is urgently recommended in accordance with DIN 7080/ DIN 8902 that the glass disc and gaskets are replaced by new ones. That is particularly important in the case of pressure vessels and/or aggressive media. The following extract from DIN 7080/DIN 8902 text is verbatim: Sight glass discs may only be installed by personnel who have been informed fully about the following requirements: care in handling sight glass discs cleaning of recesses, sight glass discs, gaskets and other parts i. e. removal of foreign bodies (e. g. swarf), prior to installation/reassembly even tightening of retaining bolts Sight glass discs that have been removed after operating use must not be re used. Planned maintenance:Sight glass discs should be included in routine maintenance and periodically checked visually or using ultrasound wall thickness measuring means. In the event of damage, a glass disc must be promptly exchanged, with the plant first having been brought to a standstill. The service life of a sight glass, relative to the particular vessel in which it is mounted, should be established by regular and careful visual check of its condition.Caution: Completely demineralised water may dissolve glass – especially intensive periodical inspection required! Breakage of a sight glass:In spite of careful installation and recommended use, sight glass discs can, on rare occasions, suffer breakage through external influences. In order to prevent the entry of glass particles into products of a critical nature, e. g. foodstuffs, appropriate safety precautions should be taken by the plant manufacturer or user.  

Material: Welded end: WN 1.4404 or 1.4301 Locknut:  WN 1.4404 or 1.4301 Glass plate: borosilicate glass (220 ° C max.) Soda-lime glass (150 ° C max.) Liner: aramid / PTFE Seal:  NBR / Silicone / Viton / EPDM / PTFE Enveloped Shape:  similar DIN 11851 Nominal size:  DN50-DN200 Nominal pressure: Operating pressure: max. 10 bar Operating pressure with wiper SWI: max. 6 bar Vacuum: max. 1,3 mbar Temperature: Temperature: max. 220 ° C Below you can see 3D models of this sight glass.   Screwed sight glass type 327 for areas with high hygiene requirements The ACI screwed sight glass, based on DIN 11851 / EN 10357, is specifically designed for use in the food industry, medicine, and other areas with high hygiene demands. The threaded socket of the sight glass is welded with an open pipe socket according to DIN 11851 and EN 10357, creating a stable, permanently tight connection with the rest of the system. On the media-contacting side, a borosilicate glass disc seals the sight glass reliably according to DIN 7080. The sealing is done via a specially shaped O-ring made of NBR, EPDM, silicone, FKM (Viton®), or PTFE for milk pipe connections. A slotted nut ensures a secure grip and firm seating of all components. If the maximum operating temperature of borosilicate glass according to DIN 7080 does not meet your requirements, or if the process conditions present a problem even for the highly resistant borosilicate glass, a mica protective disc tailored for the fitting offers additional protection against temperature and steam. FEP or Halar® coatings further protect the borosilicate glass from aggressive chemicals or caustics . Like our container sight glasses, the screwed sight glass type 327 can be equipped, if needed, with sight glass wipers or with LED lights for illuminating the interior.

Material: Base flange: 1.4404 / 1.4539 /1.4571 / 1.4541 / 2.4602 / 2.4605 / other materials on request Cover flange:  1.4404 / 1.4539 /1.4571 / 1.4541 / 2.4602 / 2.4605 / other materials on request Sight glass: Borosilicatglass DIN 7080 Shape: DIN 28121 Nominal size: DN40 up to DN200 Nominal pressure: PN10 or PN25 / for higher pressures see type 322 Temperature:  Max. 200 ° C for higher temperatures see type 323 Seal: PTFE-enclosed resilient gasket (max. 200°C) Take advantage of our 360 degree 3D view for a perfect all-round view of our product.   Our round vessel sight glasses type 321 are screwed onto flanges according to DIN EN 1092-1 to allow for observation or illumination of the interior of the vessel. ACI vessel sight glasses of type 321 are designed according to DIN 28121 for operating pressures up to 10 or 25 barg. Here, a sight glass made of chemically highly resistant borosilicate glass DIN 7080 is clamped between two high-quality stainless steel flanges and a media-side PTFE-coated corrugated ring gasket. Since this gasket is situated in the force shunt, the flange parts of the sight glass are directly aligned with each other, thus protecting the glass plate as much as possible. The type 321 is delivered pre-assembled from the factory and can be mounted directly onto a flange according to DIN EN 1092-1 without additional effort. Should the unlikely event occur that the glass is damaged during operation, the entire fitting can be replaced with little effort. Our vessel sight glasses of type 321 are made from high-quality stainless steels 1.4571 (316Ti) or 1.4404 (316L). The glass material used is the industry-proven MAXOS® borosilicate glass according to DIN 7080. The sealing in the force shunt prevents settling of the gaskets, making it unnecessary to retighten the tension screws on site. The PTFE-coated gasket makes the vessel sight glass type 321 suitable for food, acids, alkalis, and most aggressive chemicals. If the borosilicate glass DIN 7080 does not meet your requirements or the process conditions themselves pose a problem for the highly resistant borosilicate glass, a custom-made mica protection plate for the fitting provides additional protection against temperature and steam. FEP or Halar® coatings additionally protect the borosilicate glass from aggressive chemicals or alkalis. As with other sight glass fittings, type 321 can be equipped upon request with a sight glass wiper type SGW, spray devices SVII, or lights.