Which method shows bubbles or foams at a leak?

• A. Ultrasonic Leak Detector
• B. Microfoam Solution
• C. Trace Gas Detector
• D. Electronic Leak Detector

Answer: (B)

Using a soap or microfoam solution to visualize leaks relies on gas escaping through the joint and forming visible bubbles in the liquid. When you apply the solution to suspected areas and pressurize the system, any leak will create bubbles exactly where gas escapes. This gives an immediate, visible indication of the leak’s location, which is especially helpful during brazing or soldering practice because you can directly confirm joint tightness. The bubbles appear as a ring or stream at the leak, with the size and rate of bubble formation correlating to the leak’s magnitude. Other methods detect leaks without showing visible bubbles: ultrasonic detectors listen for the sound of escaping gas, trace gas detectors sense a specific tracer gas with sensors, and electronic leak detectors use sensors to detect gas presence. None of these produce the visible foam or bubbles, so the soap solution method provides a straightforward visual confirmation.