Kunyo supplies standard DIN 7080 sight glass discs as well as customized circular glass components. Special diameters, thicknesses, holes, steps, grooves and edge-processing options can be manufactured according to drawings or samples.

Key Features and Advantages

• Excellent Chemical Resistance Resistant to water, acids, alkalis and many industrial chemicals for reliable service in demanding environments.
• High-Temperature Performance Borosilicate glass offers excellent thermal stability and resistance to rapid temperature changes.
• Pressure-Resistant Construction Thermally toughened glass provides improved mechanical strength for use in compatible pressure-rated sight glass assemblies.
• Clear Process Observation High light transmission and polished surfaces provide a clear view of liquid level, flow, color and process conditions.
• Clean and Stable Material The glass does not contaminate the process medium, making it suitable for water, food, pharmaceutical and chemical applications.
• Precision Machining Precisely ground edges and polished surfaces support accurate installation and uniform sealing.
• Standard and Custom Sizes Available in standard DIN 7080 dimensions, with custom diameters, thicknesses and machining options upon request.

Technical Specifications

Parameter	Specification
Material	Premium Borosilicate Glass 3.3
Standard Compliance	DIN 7080
Maximum Operating Temperature	Up to 280°C (536°F) – Higher with specific designs
Thermal Shock Resistance (ΔT)	265°C (depending on product specification)
Bending Strength	≥ 150 N/mm²
Surface Finish	Ground and polished
Pressure Rating	Varies significantly with diameter and thickness (e.g., DN 80 x 12mm for 16 bar)

Size

DIN 7080 borosilicate sight glass discs are available in multiple outside diameters and thicknesses for industrial tanks, vessels, reactors and pipeline sight glass fittings. Select the required size from the table below or contact us for custom dimensions.

Product Code	D (mm)	T (mm)	Pressure (bar)	Size* (mm)
SD01	30	12	150	30×12
SD02	30	15	200	30×15
SD03	40	10	40	40×10
SD04	40	12	50	40×12
SD05	45	10	40	45×10
SD06	45	12	50	45×12
SD07	50	10	25	50×10
SD08	50	12	40	50×12
SD09	55	10	25	55×10
SD10	60	10	16	60×10
SD11	60	12	25	60×12
SD12	60	15	40	60×15
SD13	60	20	95	60×20
SD14	63	10	16	63×10
SD15	63	12	25	63×12
SD16	63	15	40	63×15
SD17	65	10	12	65×10
SD18	65	15	40	65×15
SD19	70	12	16	70×12
SD20	70	15	25	70×15

Product Code	D (mm)	T (mm)	Pressure (bar)	Size* (mm)
SD21	75	12	16	75×12
SD22	80	10	10	80×10
SD23	80	12	16	80×12
SD24	80	15	25	80×15
SD25	80	20	40	80×20
SD26	90	10	8	90×10
SD27	95	10	6	95×10
SD28	95	15	16	95×15
SD29	100	10	7	100×10
SD30	100	12	10	100×12
SD31	100	15	16	100×15
SD32	100	20	25	100×20
SD33	100	25	40	100×25
SD34	105	15	16	105×15
SD35	110	20	25	110×20
SD36	113	15	10	113×15
SD37	115	15	10	115×15
SD38	120	15	10	120×15
SD39	125	15	10	125×15
SD40	125	20	16	125×20
Product Code	D (mm)	T (mm)	Pressure (bar)	Size* (mm)
SD41	125	25	25	125×25
SD42	125	30	40	125×30
SD43	135	25	25	135×25
SD44	150	15	8	150×15
SD45	150	20	10	150×20
SD46	150	25	16	150×25
SD47	150	30	25	150×30
SD48	175	20	10	175×20
SD49	175	25	16	175×25
SD50	175	30	25	175×30
SD51	200	20	8	200×20
SD52	200	25	10	200×25
SD53	200	30	16	200×30
SD54	210	25	10	210×25
SD55	250	25	8	250×25
SD56	250	30	10	250×30
SD57	265	30	8	265×30
*other customized size not in this chart is available.	*other customized size not in this chart is available.	*other customized size not in this chart is available.	*other customized size not in this chart is available.	*other customized size not in this chart is available.

Industrial Applications

Circular sight glasses are indispensable in industries where visual process control and safety are paramount.

• Chemical & Pharmaceutical Processing: Monitoring reactions, mixing, and filtration in vessels and pipelines, especially with aggressive media.
• Food & Beverage Industry: Ensuring product quality, hygiene, and process integrity in sanitary applications.
• Power Generation: Observing boiler drums, condensate lines, and other critical points in power plants.
• Petrochemical & Refining: Visual inspection of various fluids and processes in high-pressure and high-temperature environments.
• Water Treatment: Monitoring filtration, aeration, and chemical dosing processes.
• Any pressure vessel requiring visual access: Where a secure, clear window into the process is essential.

Frequently Asked Questions (FAQ)

Q: When should borosilicate sight glass be selected?

A: Borosilicate sight glass is recommended when the application involves:

Continuous operating temperatures up to 280°C- 300°C

Rapid temperature changes of up to approximately ΔT 230°C

Continuous or cyclic liquid or gas pressure

Contact with water, steam, acids or many industrial chemicals

The permissible working pressure of borosilicate sight glass is not a single fixed value. It must be determined according to the glass diameter, thickness, clear viewing diameter, operating temperature and mounting arrangement.

Q: What is the difference between borosilicate, aluminosilicate, quartz and soda-lime sight glass?

A: The main differences are operating temperature, pressure capability, thermal shock resistance and cost.

Soda-lime sight glass is an economical option for general, low-temperature observation applications. Its typical operating temperature is up to approximately 150°C, and it is primarily used in low-pressure systems.

Borosilicate sight glass offers good chemical resistance and thermal shock resistance. It is suitable for most industrial tanks, pipelines and process equipment, with a typical operating temperature of up to 280–300°C. Specially designed assemblies may withstand pressures up to 200 bar.

Aluminosilicate sight glass provides higher mechanical strength and is suitable for elevated-temperature and high-pressure applications. Its typical maximum operating temperature is approximately 375°C. Properly designed assemblies may operate at pressures up to 225 bar.

Quartz sight glass provides excellent high-temperature and thermal shock resistance, with a typical operating temperature of up to 1,000–1,100°C. It is commonly used in furnaces, reactors and thermal-processing equipment. However, quartz does not automatically provide the highest pressure resistance.

All pressure values are for reference only. Actual allowable pressure depends on the glass diameter, thickness, edge finish, mounting assembly, gasket, operating temperature and required safety factor.

Q: What information is required for a quotation?

A: Please provide the following information:

Material

Outside diameter

Thickness

Quantity

Operating temperature

Operating pressure

Process medium

Hole size and position, if required

Drawing or sample, if available