一，basic definition
Flange sight glass is an observation device installed on pipelines or equipment through flange connection, mainly composed of stainless steel frame and transparent window, used to observe the internal medium status (liquid flow, reaction process, liquid level height, etc.) in real time, ensuring production safety and quality control.
二，Core structure and working principle
1. Structural composition
Mirror glass: a core observation component, usually made of tempered borosilicate glass or quartz glass
Stainless steel frame: made of 304/316L material, with strong corrosion resistance
Sealing system: PTFE gasket, high temperature resistant, corrosion-resistant, in compliance with FDA standards
Compression device: Internal hexagonal bolt, evenly tighten two flanges
2. Working principle
Fix the sight glass on the equipment or pipeline through flange connection to form a pressure resistant sealed observation window. Operators can directly observe the internal medium state through high-strength tempered glass without disassembling the equipment
三 、 Technical parameters and performance characteristics
Key parameters
| parameter | standard range | special specifications |
| caliber | DN40-DN200 | Up to DN300 |
| work pressure | ≤2.5MPa（25bar） | High pressure type can reach 10MPa |
| Operating Temperature | Ordinary glass: 0-120 ℃ Borosilicate glass: -20-230 ℃ Quartz glass: -50-550 ℃ | Special material can withstand higher temperatures |
| 材质 | Shell: 304/316L stainless steel Window: Tempered glass/Tempered borosilicate glass/Quartz glass Sealing: PTFE/FKM | PFA lined for extremely corrosive environments |
2. Core advantages
Comprehensive observation: clear field of view, no blind spots
Safe and reliable: Tempered glass has an impact strength 3-5 times that of ordinary glass, and when broken, it forms obtuse angled particles, making it less likely to harm people
Strong adaptability: acid and alkali corrosion resistance, high temperature resistance, suitable for various harsh working conditions
Easy installation: flange connection for easy maintenance and replacement
四、 Key points for installation
1. Installation steps
Identify a location on the device that is easy to observe, avoiding welds and obstacles
Ensure that the flange contact surface is clean and undamaged, and install PTFE sealing gaskets
Place the mirror between two flanges and align the bolt holes
Tighten the bolts evenly diagonally to avoid uneven force that may cause glass breakage
