The “Gross to Fine” method starts off with large “sweeping” motions, 180 degrees, left to right and up and down. You continue doing this until you start hearing “whooshing or hissing” sounds in your headset. Once you start hearing these noises you will start walking towards these sounds and at the same time your sweeping pattern will be “finer” as you get closer to the source of the leak. As you get closer to the source of the leak the noise will get louder in your headset. Note: Before the noise gets too loud adjust your sensitivity lower. Think of your sensitivity as a volume control. Your scanning module will get you close to the leak but it will not be able to pinpoint exactly where the leak is because of its wide field of view. The field of view for the scanning module is about 60 degree which will get you within a one-foot area, but in order to know exactly where the source of the leak is you will need to slide your rubber focus module over your scanning module. The rubber “boot” will drop the field of view of your scanning module from 60 degrees to about 9 degrees which will then help you pinpoint exactly where the source of the leak is emanating from.The most common mistake that I see people make is to pay more attention to what you see on your display than what you are actually listening to. The display can be very misleading because the instrument will also pick-up “competing ultrasound” as well as leaks. So it is imperative that you pay closer attention to what you hear through your headset than what you see on your Ultraprobe display. For example, you could pick up ultrasound from an air knife that is blowing air on purpose, which is why it is recommended that you turn this type of equipment off before your inspection. Otherwise, the air knife will mask the real leaks that you are actually trying to find.
Next month I’ll cover tips for taking the data you find in the field and turning it into a Compressed Gas Report that will essentially be a treasure map that you can share with your supervisor—the treasure? Cost savings and rock star status!Software Sage Stan Hewlett