Double Window Sight Glass for Pipelines with Large & Medium Diameters

Double window sight glass is a simple assembly consisting of two glasses and a cast body. It allows operators to observe and monitor the industrial fluids passing through the pipeline without affecting the normal operation of the system.

It is generally used for spot inspection and view of process parameter as it offers great dynamic visual monitoring of fluidity of fluids.

As a result, it can be used in chemical towers with high temperature, strong corrosion, and easy crystallization to ensure work safety. Featured by small drive torque, and quick, easy operation, it performs good flow regulation function and has great sealing properties.

Double window sigh glasses are generally applicable to pipelines with large & medium diameters and low & medium pressures, for example, it can be used to check water level, chemical, coolant and oil conditions in various industrial sectors.

Double window sight glass

Double window sight glass


  • It keeps fluids warm and prevent liquid from crystallizing.
  • Easy installation & maintenance. Gauge glasses and the body are connected through flanges, easy to dismantle, maintain and clean.
  • High accuracy. The integral structure of double window sight glass eliminates the occurrence of false level readings and improves the accuracy of observation.
  • Safety guarantee. It has good sealing performance and is suitable for chemical towers with high danger factor to reduce the leakage of chemicals and safeguard the personal safety of workers.
  • High temperature resistant and good corrosion resistant.
Specification of Double Window Sight Glasses
Nominal Diameter (DN) 15–200 mm
Body Material Carbon steel, stainless steel, FRP, carbon steel lined with fluorine, FRPP
Gauge Glass Material Soda lime glass, high borosilicate glass, quartz glass, organic glass
Operating Pressure 0.6–2.5 MPa
Operating Temperature 0 °C to +550 °C
Gasket Material NBR, PTFE, graphite composite
Way of Connection Flange
Surface Treatment Anti-corrosion paint treatment for carbon steel; pickling or polishing treatment for blackened stainless steel
Notes: Double window sight glasses with large diameter and high pressure are available upon request.


Double window sight glass structure diagram

Double window sight glass structure diagram

  1. Body
  2. Stud & Nut
  3. Glass
  4. Cover
  5. Gasket

Working Principle

Double window sight glasses are mounted on pipelines horizontally or vertically through flanges. When the industrial fluid flows through the gauge, the color, turbidity, and other characteristics of the fluid can be observed.


Double window sight glasses are widely used in food, chemical, petroleum, pharmaceutical industries, etc.

  • In the food industry, it is mainly used in the pipeline inspection of chocolate and sauces production processes.
  • In the chemical industry, it is mainly used to monitor the media for organic chemical production.
Double window sight glass for sauce production pipelines in sauce factories.

For sauce production pipelines in sauce factories.

Double window sight glass for chemical production in chemical plants.

For chemical production in chemical plants.

An array of tubular gauge glass is vertically placed on the desk.

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