Longwave infrared camera detects gaseous pollutants

This success has led to further product development and the introduction of an infrared camera specifically for detecting greenhouse gases that are not visible in the mid-wave infrared band; sulphur hexafluoride and anhydrous ammonia are typical examples. This new camera is the ThermaCAM GasFind IR LW, which is based on the standard model but, as its name suggests, it operates in the longwave infrared band.

Sulphur hexafluoride (SF6) is a relatively expensive man-made chemical used in, for example, electrical substations as an electrical insulator. It is also used as a cover gas in the magnesium industry, in the manufacture of semiconductors, for thermal and sound insulation, as a tracer gas for ventilation efficiency and in medical applications.

Although SF6 is extensively recycled, leakage is still a concern - and new equipment must be checked for leaks during commissioning. Excessive exposure can harm human health and, of all the internationally monitored greenhouse gases, it has by far the greatest global warming potential – 23,000 times that of CO2.

European Pollutant Emission Register

SF6 is included in the European Pollutant Emission Register that requires affected industrial plants to identify leaks from a range of 50 pollutants that they emit into the air or water in quantities over a given threshold. The ThermaCAM GasFindIR LW enables users to see - and hence tackle - the emission of sulphur hexafluoride with ease.

Although the detection of SF6 is a key selling point for this new camera, it is not by any means the only gas that it can detect. It is designed to detect a wide range of other gases too, including anhydrous ammonia that is widely used as a refrigerant in large cold-storage facilities.

The new ThermaCAM GasFindIR LW actually shows any leakage point or points of sulphur hexafluoride gas in real time. It can detect small leaks from several metres away and big leaks from hundreds of metres away and in trials has proved able to see leaks that have eluded a traditional active laser system. In addition to making leaks visible, the camera is able to scan large areas quickly, thereby greatly increasing inspection speed and improving overall plant safety. It can also be used without stopping any operation or process.

At the heart of the cooled ThermaCAM GasFindIR LW is a 320 x 240 quantum well infrared detector (QWIP) that is optimised to detect sulphur hexafluoride and other gases. Due to their absorption characteristics, the gas leaks appear as black smoke on the camera's viewer and the events can be captured on video for easy documentation or emailing.

Operating conditions

In common with its forerunner, this model is designed for operation in harsh environments and in a wide temperature range from -50 to 15degC. It has an industrial shock rating of 40G and can detect gas levels down to 5g/hr. A scan rate of 50Hz (50 frames per second) enables the efficient inspection of dynamic events without image distortion; a 25mm lens with 22degree field of view is provided as standard, but 11 and 5.5degree lenses are also available.

Weighing under 2.3kg, the ThermaCAM GasFindIR LW has an NETD of