What test method or instrument could be used to leak test a piping system containing ammonia?

• A. Ultrasonic leak detector
• B. Electronic leak detector
• C. Soap bubbles
• D. Halide torch

Answer: (C)

The important idea here is that a visual, hands-on leak test method is often the quickest and most practical way to find where ammonia is leaking from piping. The soap bubble test works by applying a soapy solution to joints, flanges, and welds while the system is pressurized to a safe test pressure. If there’s a leak, gas escaping through a joint creates visible bubbles where the leak is located. This gives an immediate, easy-to-see indication of leak points without needing specialized equipment, which is especially useful for toxic gases like ammonia because you can perform the test with basic precautions and ventilation.

Why this approach fits ammonia piping well: it doesn’t depend on sensor performance or flame chemistry, and it provides a clear yes-or-no indication of leaks at precise spots. It’s also inexpensive and quick, allowing you to identify multiple leak sites in one pass.

By contrast, ultrasonic or electronic leak detectors rely on sensing sounds or specific gas signatures and can be misled by background noise or require sensors tuned to the exact gas. A halide torch tests for halogen-containing refrigerants and uses flame chemistry, which isn’t appropriate for ammonia and isn’t a safe or reliable method for this gas.