It now helps utilities identify leaks of sulfur hexafluoride at their substations. SF 6 is widely used as an insulator in electrical equipment, particularly in high-voltage circuit breakers and switchgear. The gas is an ideal dielectric, or nonconductor of electricity, but although it is chemically inert, has been assessed as a contributor to the greenhouse effect. Recently, the U.S. Environmental Protection Agency in Washington has begun requesting electric utilities to voluntarily reduce SF6 leaks at their plants. This involves de-energizing the equipment, and spraying liquid soap on it.
Gas leaks create bubbles.
Sniffers are gas detection units that vacuum air samples from equipment to detect the presence of SF6. Both techniques require the leak inspector to be in close proximity to the equipment, which often means excessive climbing and reaching if the equipment is off the ground. A decade ago, Tom McRae, a physicist working at Lawrence Livermore National Laboratory in Livermore, Calif., developed a laser-based detection system to pinpoint fugitive emissions from chemical plants and oil refineries. These so-called GasVue devices emit a wavelength of laser light that will be absorbed by a target gas. An integral infrared camera captures the light reflected from the target and displays it on a screen.