Visilume Sight Glasses

Visilume supplies a wide range of sight glasses for viewing the contents and also the level of tanks, vessels or pipelines. Sight glasses allow you to monitor liquid flow either manually or at a distance.

The Description About Visilume Sight Glasses

Sight glasses can be installed by welding, bolting or clamping into your equipment. Sight glasses are assembled to suit the needs of your specific plant and vary in pressure from high vacuum through atmospheric to high pressures up to 250 bar. There is a very wide range of applications so there are sight glasses suitable for each application from cryogenic through to furnaces.

Sight glasses can be as small as 6mm and as large as 600mm. Sight glass surrounds are made of diverse materials to suit your process, these include aluminum, carbon steels, stainless steels, duplex stainless steels and hastelloy.

We have a wide range of sight glasses to suit different processes and environments:

Visilume Limited is a 100% employee owned company.

Having remained an independent company since it was founded in 1984; Visilume has built up a strong UK and International customer base by prioritising customer service and providing easy access to technical expertise.

In 2014, we transferred a controlling stake of the company to employees, and in 2021 we became fully employee-owned. We have now created a structure that will secure the long-term future of the company, and the core objectives of continued independence and providing excellent customer service.

Visilume Sight Glasses Products

Visilume Sight Glasses

Sight Glass Fittings

Sight glasses, also called sight windows or view ports, comprise two flanges, bolted together, surrounding a glass disc sealed with gaskets and provides a means of viewing the inside of a process vessel or tank. They are typically used to visually verify stages of a process, inspect process media, and to observe liquid levels. Common applications include the viewing of internals of pressure vessels, tanks, silos, stirred vessels, separators pipelines etc.

Light Fittings & Cameras

Our sight glass light products (also called” luminaires”) illuminate process vessel interiors in pharmaceutical, food processing, and chemical plants. Available in standard and explosion-proof {ex-lights} housings as well as halogen or LED designs.

Please note:

Halogen bulbs are being gradually discontinued. This is the final stage of a European Union directive (EC 244/2009) that has progressively banned less efficient light sources, with the aim of improving energy efficiency and cutting carbon emissions across the EU. Halogen light bulbs fall foul of the regulations as they use much more energy than alternatives such as LEDs. They also have a relatively short lifespan of around 2,000 hours – approximately two years when used for around three hours per day.

The output of a typical halogen bulb is 15% light and 85% heat, with the heat coming from the infrared light the bulb produces, which can’t be seen by the naked eye. Unlike halogens, LED luminaires produce 55.6 lumens per watt of electricity consumed while producing little or no heat. In contrast with halogen lights, which have fragile filaments, LED’s are vibration and impact resistant, offering dramatically longer lifetimes for lower maintenance costs and fewer process interruptions.

Flow Indicators

A sight flow indicator is used in process pipelines to observe the flow of liquid, powder or gas. It is comprised of a body with one or more viewing windows. It is the most reliable way to verify flow for direction and approximate rate, colour and clarity. We offer standard view and full-view sight flow indicators for industrial, sterile and hygienic applications.

Our range, with a choice of materials including stainless steel, carbon steel and duplex bodies, suit industrial applications with working temperatures up to 250ºC and working pressures up to 16 bar for the standard range and 40 bar for the high pressure range, and up to 250 bar for custom applications.

Custom Sight Glass Fittings

Custom sight glasses are uniquely designed to suit your application. Available for a wide range of pressures and temperatures, which are dictated by the viewing area, material specification and working environment.

Pressure Vessel Clamps

Quick release pressure vessel clamps offer an economic and safe alternative to conventional bolting when assembling pressure vessels and pipelines. They offer the following benefits to manufacturers of pressure vessels, reactors (including glass lined vessels), filter housings and a wide range of pressure equipment

Level Indicators

Magnetic Level Gauges are ideal for toxic, corrosive or flammable liquids and suitable for both hazardous and safe areas, with an enclosed unit that guarantees process plant and operator safety. With stabilised indicator flags that ensure reliable and accurate operation unaffected by vibration. The indicator is available in a wide range of sizes with many material and connection options, including remote switching options for integration into plant control system. Operating pressures up to 250 bar and temperature from -200°C to +400°C.

Bursting Discs

Due to their construction, composite bursting discs (composite rupture disks) are ideal for use at low to medium burst pressures. Using the latest laser technology, we cut special predetermined breaking points in foils of stainless steel, nickel, nickel-based materials (Inconel, Hastelloy)* or tantalum with the highest precision and can set the exact bursting pressure required by our customers. It is therefore possible to achieve low pressures from 20 mbar (at an operating temperature of 20 degrees Celsius). If the operating pressure exceeds the permitted value, the foil will tear segmentally or fragment-free in a hinge-like pattern. So they can easily be installed in front of a safety valve.


Metaglas can replace conventional glass in many applications including circular flange assemblies for welding into vessels, weld neck & nozzle flanges and sight flow indicators.

  • In addition, Metaglas cover flanges can be mounted onto flat face base flanges, these are available for all international flange connections including ANSI & BS. Existing installations can therefore be easly retrofitted to improve safety and extend plant life. The unique pro­perties of Metaglas  also make it ideal for use with sanitary mounting systems.
  • Metaclamp’s are available as sight glass caps for sanitary clamp and In-line systems and sight glasses and Luminaire adaptors for sterile flush mount designs such as the NA-Connect system and Triclamp fittings.
  • Metaglas has been subjected to the most rigorous tests by specific testing facilities in the chemical industry and has subsequently been integrated into their works standards.


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