One of the most prominent complicating factors for any leak detection and repair (LDAR) program are potential adverse weather conditions. For whatever methodology you use in your business, environmental conditions will always be a complicating factor no matter how new your equipment is or how experienced your technicians are. Here are a few things to keep in mind when dealing with weather-related issues.
It’s worth noting that both more conventional methods like Method 21 as well as infrared imaging technology are affected by the environment, albeit in different ways and to a much different extent. Both methods are hindered by rain, fog, wind, humidity, and cold weather to some degree or another. More technologically advanced solutions, such as Optical Gas Imaging, still can struggle as lousy weather reduces the effective detection limit of infrared cameras.
Wind can make it harder to detect leaks in more extreme conditions, but when calmer, wind can help visualize escaping gases as it gets spread around by the breeze. However, it doesn’t take much for a steady gust of air to make your fugitive emissions nearly impossible to spot. Wind speeds higher than 12 mph tends to be the tipping point as the detection efficiency usually drops to just 10 percent of total leakages. Often, early morning and late evening are the best times of the day to perform inspections as wind speeds are lower, although not always.
Rain is another significant hindrance to LDAR programs, as precipitation and fog serve to mask the presence of leaking gases completely. Light conditions don’t disrupt the quality of the equipment too much, but heavy rain, dense fog or snow will create problems getting an image of a gas leak. When coupled with the fact that rainstorms often are accompanied by windy weather as well, the two tend to come hand in hand.
Humidity is another factor that prevents operators and equipment from getting useful readings. Thermal imaging cameras produce an image based on the differences in thermal radiation that an object emits. Essentially, the farther this signal has to travel to reach the camera, the more of the signal that can be lost along the way. Humid air acts as a “shield” for infrared radiation, dispersing it rapidly as it travels over long distances. The greater the humidity, the closer your equipment needs to be, to pick up escaping emissions.
One thing to be aware of is that recent EPA regulations don’t specify many of these crucial weather conditions in their testing protocol. Often it’s up to field operators to decide the maximum viewing distance, acceptable wind conditions, and temperature for testing leaks. With such a latitude in procedure, operators can perform a leak detection survey without actually finding anything to note. Companies would do well to standardize the protocol for weather conditions in all future LDAR programs if they haven’t already done so.
Keeping these things in mind will not only help standardize your LDAR results, but it will also make sure that you are making the best use of your equipment, time, and personnel.