SF6 portable devices

Photo - acoustic infrared detectors operate based on the pressure waves emitted by SF6 molecules when they are illuminated by monochromatic infrared light. Specialized microphones detect the acoustic signal, which is directly proportional to the energy absorbed. Sensitivities as low as 0.01 μl/l can be attained, far surpassing those of other methods. However, the response time of approximately 15 s restricts the use of this device for leak localization.

Electron capture detectors utilize a ß - particle source to ionize a pumped sample. The ion current between electrodes is then measured. An inert gas carrier is commonly employed. This method is expensive and significantly less portable compared to item 3. Sensitivities down to 0.1 μl/l (0.1 ppmv) of SF6 in air can be achieved.

Corona discharge cells apply a high voltage (1 - 2 kV) to a point - plane electrode configuration. The discharge current is measured and is used in a variety of highly portable, battery - powered units that are relatively low - cost. Sensitivities below 10 μl/l can be achieved, although not with all available units.

Items 1 and 2 are generally utilized for leak tracing and quantification. Item 3 is suitable for either determining whether an area contains SF6 or for leak detection.