side profile rectangular sight window
rectangular sight glass front view
Rectangular Sight Glass — Flat Rectangular Sight Window - Image 3
edge detail rectangular sight glass
Rectangular Sight Glass — Flat Rectangular Sight Window - Image 5

Rectangular Sight Glass — Flat Rectangular Sight Window

Rectangular sight glass and rectangular sight windows for inline inspection. Flanged and weld-on options, borosilicate or tempered glass, custom sizes. Datasheet & COA available.

Category:

Description

Rectangular sight glass provides a wide, flat viewing area for tanks, vessels and process lines. Designed for clear visual inspection over longer spans, our rectangular sight windows combine durable borosilicate glass with stainless housings. They fit flanged, weld-on and cartridge-style assemblies. Download the datasheet or request a custom quote below.

Why choose a rectangular sight glass?

  • Wide view: The flat shape gives a continuous field of view across height or width.
  • Durable materials: Borosilicate or tempered glass paired with 304/316 stainless steel bodies.
  • Flexible mounting: Flanged, weld-on, threaded or cartridge options for fast installation.
  • Custom sizes: Made to order to match your opening or inspection requirement.
  • Tested & traceable: Batch COA and pressure/temperature testing available.

Typical specifications

 

Rectangular Sight Glass — Specifications

Product type Rectangular sight glass / flat sight window
Window material
  • Toughened sodium silicate glass to DIN 8903 (max. 100 °C)
  • Toughened borosilicate glass to DIN 7081 (max. 243 °C)
Body material RSt 37-2 or Hll (boiler plate) /AlSl 316 Ti stainless steel
Gaskets:
  • KLINGERsil C4400/Neoprene
  • PTFE/Viton
Certificates: To be supplied against an extra charge to DIN EN 10204.
Options:
  • Version with closed base frame (drawing left) to be used as an external liquid level gauge with top and bottom pipe connections. For this application, the base frame will be supplied appropriately drilled and tapped.
  • Radiused base frame to suit the vessel wall
  • Clear(transparent)glass plate
  • Alternative versions in shape and size
Operating temperatures:
  • 100℃ max. with sodium silicate glass to DlN 8903
  • 243℃ max. with borosilicate glass to DlN 7081

Note: The above indicated temperatures refer to the use of unprotected glass plates, with no protective mica sheets.
Operating conditions:
  • Nominal pressure 16 bar
  • Vacuum

Note: The nominal pressure indicated refers to the design base of the sightglass. When welded into the vessel concerned, the base frame becomes part of the vessel wall. lt is necessary, therefore, that appropriate strength calculations are made on all vessels concerned with respect to the design pressure and size of the vessel and in accordance with the relevant design code. if found to be necessary, reinforcement of the vessel wall has to be carried out.

Need a custom size or specific material? Contact us for a quote.

Features & benefits

  • Continuous inspection: See the level, flow, and surface condition across a flat area.
  • Low contamination risk: Glass window avoids metallic debris in process lines.
  • Easy maintenance: Replace cartridges or glass packs without cutting pipework (three-piece models).
  • Coatings & treatments: AR, anti-fog, or scratch-resistant coatings available.

Applications

Rectangular sight windows suit chemical vessels, mixers, separators, food & beverage sight lines, and process tanks where a broad field of view is required.

Ordering information

Provide: rectangular opening size (W x H), glass thickness, flange type, material, and operating conditions (pressure, temperature, media). For custom quotes, upload drawings via Request Quote — Upload DWG/STEP.

Downloads

Rectangular Sight Glass — Datasheet (PDF): rectangular-sight-glass-datasheet

FAQ

1. What is the best glass for high abrasion?
Borosilicate or tempered glass is a good choice. For extreme abrasion, consider protective coatings or laminated solutions
2. Can you make custom rectangular sizes?
Yes. Provide DWG/STEP or dimensions; we will confirm manufacturability and lead time
3. Do you supply flanges to match ANSI/DIN/GB?
Yes — specify your required flange standard and drilling when ordering.

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