一、 Basic Definition
Flange sight glass is a commonly used visual accessory for tanks, reaction vessels, and pressure vessels; Relying on the upper and lower flange bolts to clamp the mirror glass, the flange is directly welded to the equipment cylinder for intuitive observation of the internal material status (liquid level, flow, reaction, foaming, turbidity, crystallization, etc.) without opening the equipment.
二、 Infrastructure composition
1，Flange body: compression flange+base flange,
2，Mirror glass (core)
Tempered borosilicate glass: mainstream, temperature resistance ≤ 280 ℃, cold and hot shock resistance,
Quartz glass: High temperature working conditions, short-term maximum 800 ℃, higher price
3，Sealing gasket: PTFE PTFE, silicone EPDM、 Graphite gasket (anti-corrosion/high temperature selection)
bolts fastener
三、 Mainstream classification
1，Flat neck flange mirror (most commonly used)
Two flanges are directly clamped onto the glass and welded to the flat area of the tank body; cost-effective DN50~DN200。
2，Neck flange sight glass (JB595/HG/T21620)
Add a short neck at the bottom of the flange for connecting pipes; Isolate welding stress, suitable for curved heads and high-pressure vessels, to prevent glass leakage caused by welding deformation.
3，Derivative allocation options
Flange mirror with light: equipped with explosion-proof LED spotlight, for observation inside a dark tank
Equipped with scraper mirror: The medium is prone to scaling and sticking to the wall, and the built-in scraper is used to clean the glass
Square rectangular flange mirror: large observation field, used for large storage tanks
四、 Common material selection
Flange shell
304 stainless steel: food, general chemical, water, oil products
316/316L stainless steel: weak acid and weak alkali, pharmaceutical, fine chemical industry
WCB carbon steel: non corrosive atmospheric pressure condition, low cost
window glass
Tempered borosilicate glass: industry standard
Quartz glass: high temperature, strong ultraviolet working conditions
gasket
PTFE (tetrafluoroethylene): resistant to the vast majority of corrosion; Commonly used in food and medicine (can meet FDA requirements)
Silicone/EPDM: Room temperature pure water, food medium
Graphite gasket: High temperature working condition
五、 General Technical Parameters
Nominal diameter: DN50, DN65, DN80, DN100, DN125, DN150, DN200
Pressure rating: PN0.6/PN1.0/PN1.6/PN2.5 MPa
Operating temperature:
✅ Borosilicate glass: -20~280 ℃
✅ Quartz glass: ≤ 800 ℃
六、 Application industry
Petrochemical, fine chemical, biopharmaceutical, food and beverage, water treatment, coatings, lithium battery slurry, daily chemical reaction kettle, fermentation tank.
Observation contents: liquid level, mixing flow, reaction color change, presence or absence of foam, precipitation, material stratification.