VTL-5 Furnace Viewing Television System

This system provides a cost-effective method of viewing the interior of an operating furnace or boiler, providing high-quality colour pictures of furnace contents and flame pattern.

A miniature solid-state colour television camera is contained within a watercooled housing that is inserted through the furnace wall or roof to view the interior from a position that is effectively at the hot face of the refractory.

Features and Benefits

  • There are no windows between the lens and the furnace interior and the picture quality therefore remains excellent without the need for any routine cleaning or maintenance.
  • A special lens views directly into the furnace through a small aperture in the housing, which is provided with a refrigerated air purge which exhausts through the viewing aperture and provides front-end cooling for the lens as well as keeping it clean. The unique design of the housing ensures that the purge air seal is maintained during camera removal until the camera and lens assembly is withdrawn sufficiently that there is no thermal hazard from the loss of cooling air.
  • A local junction box houses camera power supplies and alarm circuits and provides interface facilities for fixed site cabling. A local video test point and mains power outlets for test equipment are also provided within the box.
  • Camera temperature is continuously monitored by a thermocouple sensor and an alarm is generated if this exceeds a preset limit.
  • Other sensors monitor air pressure and cooling water flow and have individual alarm channels. An alarm is indicated by a warning lamp on the camera junction box, and separate volt-free changeover contacts are provided for integration with plant alarm systems.
  • All alarm systems are designed to be failsafe in the event of a power loss or other system failure.
  • The pictures are presented on a metal-cased industrial video monitor at the operator's location, and the only connection between the monitor and camera positions is  single coaxial cable. (Alarm connection is to user's choice depending on plant operating systems)

Scope of supply

The system as supplied includes all hardware required for a complete operating system, the only user-provided items are cabling between the camera and monitor, and required alarm connection, and electrical, air and water services.

Optional items include: automatic retraction systems to withdraw the housing from the hot zone in the event of an alarm being detected; remote alarm panels and annunciators; panel, wall or ceiling mounting of monitor; and a complete installation and commissioning service.

VTL-5 is one of a range of furnace and boiler viewing systems that is the most comprehensive available anywhere. Video Technology Ltd also manufactures a wide range of other industrial video systems and optical data gathering instruments; if there is no standard system available to do what you require, we will design and manufacture one for you.


Camera: Solid-state unit with 1/3" CCD sensor
PAL/NTSC format as appropriate
Lens: Auto-iris with 75°, 55° or 45° horizontal field of view
Housing: Stainless-steel double reverse flow design, with special protective coating. Length to suit furnace wall and refractory thickness, typically 800mm
Diameter 90mm
Weight (full) approximately 15kg
Junction Box: Size 500mm (h) x 500mm (w) x 210mm (d) Stainless steel for corrosion resistance
Monitor: (Standard) 36cm (14") picture tube metal-cased industrial unit
Size 318mm (h) x 347mm (w) x 388mm (d) - other sizes available
Services: Water: Minimum 5 litres/min with inlet temperature of 35°C or less
Should be reasonably free of sediment
Air: 240 litres (8ft³)/min free air inlet pressure of 5-7 bar (60-100 psig)
Filters are supplied to ensure suitable air quality when fed from plant air supply
Electrical: Junction Box: 90-260V AC, 47-63Hz
Normal current drain less than 0.5A but local mains outlet for test equipment means that at least 2A supply should be installed.
Monitor: 240/110V 50Hz or 115V 60Hz as appropriate
Approximately 65 watts
Cabling: A 75 ohm coaxial cable is required between junction box and monitor locations; alarms will depend on local requirements, but for full duplication at remote point a 9 core cable is required
There is no practical limit on the distance between camera and monitor, but if this is very large (above 400 metres) additional equipment is required to process and amplify the signal.

Due to our policy of continual product development, specifications may change without notice.

All Video Technology products are designed and built in Britain.