Sight Glass

The objective of a sight glass is to provide a window into a pressure vessel, a hot temperature or corrosive process environment, for machine vision or live observation. We manufacture and distribute sight glasses, sapphire and quartz windows as well as laser window assemblies. Encole offers stock and custom high pressure sight glasses for energy, food processing and pharmaceutical applications. We also offer sight windows for ultra high vacuum in semiconductor applications. Sight windows available through the catalog cover a broad spectrum of transmitted wavelengths, from infrared to ultraviolet.

Listed sight glasses in the table are products released to production. These are stable designs that have been fully engineered, tested and proven in the field in various uses.

Sight glass manufacturers offer custom configurations upon request. The most common custom designs are high temperature and high pressure sight glasses. These are typically NPT or Flanged sight windows where the glass is brazed to the housing. For applications requiring higher operating temperatures, above 500 degrees C, the window is typically made from sapphire. It is sealed into the housing with a metal C-seal, made from Inconel(R), Alloy 718, or Waspaloy(R).

Fused sight glasses with borosilicate glass are commonly used in heaters, oil tank sights, liquid level applications where operating temperatures do not exceed 300 degrees C. For excellent optical clarity we recommend viewports and sight windows with quartz or sapphire windows polished to minimum 40-60 S-D. These sight glasses are typically used in imaging systems or in conjunction with laser sensors. Use the Filter to the left of the table to select the right sight glass based on the application parameters.