🔍 Key Concepts

• Difference between chemical sniffers (designed for halogen/refrigerant/combustible gases) and acoustic/ultrasonic leak detectors • Properties of nitrogen as an inert, odorless gas when used as a test pressure medium • Which tools in the illustration rely on sensing specific gas types versus sensing the sound of escaping gas

💭 Think About

• Look at the labels and shapes of each device. Which ones are clearly marked or configured for refrigerant or combustible gas only? • If the system contains only nitrogen, which type of detector would still work even if it cannot "smell" or chemically react with the gas? • Which pictured device appears to work with headphones or a listening horn, suggesting it detects sound rather than gas composition?

✅ Before You Answer

• Eliminate any option that is obviously a refrigerant-specific detector. • Eliminate any option that requires a flame or chemical reaction with the leaking gas. • Select from the remaining choices the one that uses an acoustic/ultrasonic sensing method, which will work with nitrogen or any other pressurizing gas.