Video: TC721

Video transcript

Which gases this camera makes visible, how it differs from a camera for SF₆, and how to use it to survey a plant. A leak of methane, propane or solvent vapour is invisible. Every one is lost product and a fugitive emission, and many of these gases are combustible. What is needed is a way to see the leak from a distance, while the plant keeps running. The camera looks at infrared radiation in a narrow band,

from 3.2 to 3.5 micrometres. That is where methane, propane and the other hydrocarbons absorb strongly. Where the gas is, part of the radiation from the background is missing, and the escape appears on screen as a moving plume. So the band decides the gas. The TC721 is tuned to hydrocarbons and volatile organic compounds. SF₆ absorbs far away, near 10 and a half micrometres: for SF₆ in switchgear, the camera is the TC706.

Methane, ethane, propane, butane, pentane and hexane. And beyond them, ethylene and propylene, benzene, toluene and xylene, methanol and ethanol, and dozens more of the volatile compounds found in refineries and chemical plants. This is the camera's own recording at a process plant. What leaves the vent drifts and changes shape, frame by frame, and always from the same point. In a still image it is easy to miss. In motion, it is obvious.

Faint plumes need a sensitive detector. The TC721 uses a cooled quantum well array of 320 by 256 pixels, with a thermal sensitivity of 15000ths of a degree. It detects 4 10ths of a gram of methane an hour, at two metres. There are two detection modes: standard, and a multi-level high sensitivity mode for the smallest leaks. And when the job is temperature, the same camera measures from minus 40 to 500 degrees.

Where hydrocarbons leak, the air around may be explosive. The TC721 carries an Ex certification for gas group two C, temperature class T4, so it can go into the hazardous areas of petrochemical and gas plants. On the camera: the infrared lens, with motorised focus. The 5 megapixel visible camera, between its two lights. The carrying handle, and the buttons on top. The OLED viewfinder, and the 5 inch touchscreen, which folds out from the side. It is built to be carried round a plant.

Four hours of continuous work on the lithium battery, a touchscreen or a viewfinder, a laser pointer to show a colleague the leak, GPS on the files, and a fill light for dark corners. Before a survey, charge the battery, and switch the camera on early: the detector has to cool down, which takes up to 7 minutes. Then choose the detection mode, a palette that suits the background, and check there is room on the card. Then walk the plant and scan it slowly, line by line.

Look for what drifts and changes shape, rather than what is simply warm or cold. Leaks are located from up to 80 metres, without shutting anything down. The palette matters. 11 are built in, from white hot and black hot to iron and rainbow, with automatic or manual contrast and brightness. On a busy background, a change of palette is often what makes the plume stand out from what is behind it. For thermography, it measures at up to 10 points and 10 areas at once,

along a line or as a difference, with isotherms and alarms. Emissivity, background and atmosphere are all corrected. Every finding is documented: infrared images with the measurement data inside, infrared and visible video, and a voice or text note with each image. Files leave the camera over Wi-Fi, Bluetooth or the video output. Oil and gas production and natural gas networks, petrochemical and chemical plants handling hydrocarbons, VOC leak surveys, and inspection around energised substations, with the equipment in service.

Gas leak detection, from Amperis.