To pinpoint an air leak, use which of the following on the suspected area?

• A. Soap solution
• B. Dye penetrant
• C. Ultrasound
• D. Heat indicator

Answer: (A)

For pinpointing an air leak, use a soap solution on the suspected area. When pressurized air escapes through a tiny hole or loose connection, it bubbles through the soapy liquid, making the exact leak visible. This method is quick, inexpensive, and safe for most pneumatic systems, and works well on hoses, fittings, valves, and seals. Dye penetrant is meant for revealing surface cracks in solid materials and isn’t used to detect leaking air. Ultrasound can locate leaks with specialized equipment by picking up the sound of escaping air, but it’s more complex and not as direct for a simple pinpoint in many field situations. A heat indicator relies on temperature changes and isn’t a reliable or standard way to locate an air leak.