Which statement is true regarding the use of nitrogen for pressure testing copper tubing?

• A. Vacuum pump
• B. Thermometer
• C. Regulator
• D. Manometer

Answer: (C)

The main idea here is controlling the test pressure when using nitrogen to pressure test copper tubing. Nitrogen is used because it’s inert and dry, so you can pressurize the line without risking corrosion or contamination. To do a safe and effective leak test, you need to bring the nitrogen down from the cylinder’s high pressure to a specific, manageable test pressure and keep it there. That’s exactly what a regulator does: it reduces the cylinder pressure to a set level and maintains that pressure during the test. Without a regulator, the gas could enter at too high a pressure and potentially damage the tubing or create unsafe conditions. A vacuum pump would remove pressure, not provide it, so it isn’t appropriate here. A thermometer isn’t needed for this process, since temperature isn’t what controls the leak test. A manometer can measure the pressure, but the device that makes the test possible by setting and maintaining the pressure is the regulator.