Definition and purpose
The sight glass is generally made of high-quality heat-resistant glass, processed through special techniques, and features high transparency, high temperature resistance, high pressure resistance, and good chemical stability. It is mainly used for observing and monitoring production conditions and is an essential component in chemical, metallurgical, steel mill, and pipeline industries.
Classification
High-temperature resistant sight glass: With excellent temperature resistance, it can be used under high-temperature conditions ranging from 350℃ to 1500℃ without cracking. Its thermal shock resistance temperature is between 180℃ and 1100℃, and its bending strength ranges from 80 to 220Mpa. It is a dedicated glass for various high-temperature windows or viewports.
High-pressure resistant sight glass: With high compressive strength and flexural strength, and stable mechanical properties, it can meet the working conditions under 1-30Mpa. With a flexural strength of 100-220Mpa, it is a dedicated product for various high-pressure vessel sight glasses or windows.
High-temperature and high-pressure resistant sight glass: It not only withstands a certain amount of pressure but also exhibits excellent resistance to both heat and cold. It remains unbroken even in rapidly changing temperature environments, with a maximum temperature tolerance of up to 1500℃. Its thermal expansion coefficient is extremely low, equivalent to only 1/12 to 1/20 of that of ordinary glass.
Performance Characteristics
Corrosion resistance: The sight glass material is dense and not easily corroded by water, acids, or alkalis. Except for hydrofluoric acid and hot phosphoric acid, it is resistant to all inorganic and organic acids. Its surface is not easily scratched or stained.
High transparency: It has a high light transmittance, generally above 85%-90%, allowing clear observation of the flow of internal media.
Selection considerations
When selecting sight glass, it is necessary to comprehensively consider factors such as the temperature, pressure, and chemical corrosion of the usage environment. If the operating temperature is below 500°F, borosilicate glass can be used; if it exceeds 500°F, such as in high-temperature steam environments, quartz or sapphire glass is recommended; for non-critical applications with temperatures below 300°F, soda-lime glass can be used. Additionally, the thickness and diameter/area of the glass should be determined based on the pressure of the container.
